I know this is an older video but SO HELPFUL. Super informative, easy to understand, not long winded...and amazing use of a bagel to explain a concept! Thank you so much - loved it!
Underrated video! I'm a ham and I wish I had viewed this video when I first started. Thanks for explaining antennas in such an easy way to understand. Keep them coming.
Agreed. 6 years later, still underrated. It's not exactly a master-class, but it hits the important pieces for getting 90% there, which is better than watching a master-class for hours, missing most of the concepts, and trying to apply them to get a workable antenna. One formula, and a simple modable design.
I got my FCC First Class RT Operator license in 1980, but antennas were always a weak point for me. This video bought a lot back, and made a lot clear to me. Nicely done, sir.
Please make more antenna videos! You just explained to me in 8 freakin minutes what no one else has explained to me in 20 years of casual investigation. PHYSICAL demonstrations of the antenna wiring beat every damn virtual/whiteboard drawing EVERY DAY. THANK YOU SIR! I finally actually understand WTF a dipole antenna actually is, in real life... Oh, and YEAH, what the ground plane stuff is for also!!!! 73, KD2OQN
I became clear to the concept of impedance matching after watching this video after listening to the word almost for 6 years without any logic. Wow dude... you did great.
I've watched many videos over time, read books, but have never understood my CB antenna(s), I'm not stupid, I just never found one that made sense, so I was happy to follow the rule that as long as I could get the SWR below 1.5 by adjusting the length of the 'top' part, it was good!. This video made some sense, it helped me understand concepts I wasn't sure about. The way the power is radiated, how and why the cable can be as long as the aerial, but that it's the shield that reflects the power from the center back into itself, split the two, go opersite ways and you've got less reflection, split the shield part further and you get a ground plane, So simple it actually made sense rather than the drawing in books of a upside down triangle! My D-Pole was the best by far, 10mls, and when there was 'skip' I got to chat to people in other countries! But, OMG! I actually have some understanding now! Seriously, this is like the basic 101 that I needed to kick my ass into gear in to wanting to learn and understand this topic rather than just getting the lowest SWR, I hope now to be able to look for another video or wait for you to produce one which can explain CB antennas, base loaded, mag mount vs through hole grounded, you really did a amazing video there... not too much maths, just enough to help... Thank you soooooo much!
Hello Sir - very nice demonstration and explanation. Just one slight correction I would humbly offer: around 2:40 you refer to maximum power transfer from a stereo amplifier to a loudspeaker. This may be the case in vacuum tube designs but in most solid state designs the amplifier is made to behave as a voltage source, and usually has an equivalent output impedance of milliohms. The designation of 4 or 8 ohms you may see on the speaker terminals of an audio amplifier relates to the design limits of the output stage and to the current and voltage capability of the amplifier to deliver its rated power to a load of a given impedance before either running out of current or voltage. Therefore, it does not exactly relate to the typical RF power amplifier or signal generator, where the output impedance is matched to the rated load impedance for maximum power transfer.
Thanks for the response.Yes .. In a vacuum tube amplifier the tubes drive a impedance matching transformer so the speaker load is important for maximum power transfer. These are the days I remember. Solid state class A/B amplifiers are more flexible about speaker impedance and we match more for distortion than power transfer. With the new class D power amplifiers however the output low pass filter needs to see a proper speaker load for power and frequency response. For someone who is new to antenna operation I simply used the stereo speaker output example as something they can relate to.
I know this is five years late, but that was the best video presentation of antenna pract app. You sir, should write a book, (failing that, at least more videos) expeditiously. Thanks for sharing. KC3UEE
Antenna theory is one of the most interesting 'mystery sciences' there is. They just don't work according to 'normal' electrical theory and many people just don't understand that.
You're welcome. If you want to see that type of antenna on an analyzer check out this video: ua-cam.com/video/wR-2c8VgunI/v-deo.html Thanks for the visit.
I'm a rf engineer and worked on antenna in the past. Typically when you make an dipole or monopole antenna, you should connect your antenna to a VNA and check your return loss(s11), and make sure it is tuned to the right frequency. The actual size of the antenna is shorter than the calculated value because of fringing effect.
The antenna was trimmed using an Anritsu S412E for best return loss. Fringe fields only apply to Microstrip/Patch antennas. With a wire monopole the Velocity factor (Vf) has to be taken in consideration for proper antenna size. The velocity factor is already taken care of in the formula for constructing the radiator and ground plane radials.
@@0033mer rotflmao ,,,,,, You The Man!!!!!! ,,,,,, I've been reading some of the replies,,,, some of these folks need to check themselves before attempting to check you,,, Thank you for taking them back to school! it's been confirmed, you that guy !!!!!
This is a gold mine find. Dude. You explained it better than anyone! Are you gonna make more videos where you go into how this also related to antenna math?
Thank you for this informational video! I’m just getting started in Radio Astronomy, but don’t know much about antennas, but this video certainly helps =)
Alright 2 years after the last comment, yes, helpful thank you! Honestly though, when you brought that bagel out, I lost it! and, realized I was on the right channel.
Many thanks. Can I suggest a video project for you (and for me to copy haha!)... any chance you might be able to do a project that constructs an SWR meter using the Arduino? I am certain this would be hugely popular!
I have built VSWR alarms for repeater systems using a Motorola directional coupler and a microcontroller. The directional couplers are expensive and tricky if you want to build one yourself. I would invest in a Bird 43 and learn how to use it properly ... very powerful tool.
That was really interesting. One point; the radial wires did not look like they where are 45 degrees. More like 30 degrees. I guess you could tune the wires if you have a signal strength meter. Perhaps a smart phone with a WiFi app that shows signal strength. That might make an interesting video. Thanks, I'm enjoying these videos. Short, simple, clear and no frills.
Good observation .. I built a few of these antennas with different radial angles and I happened to use that one in the video. You are correct, the best way to fine tune the antenna is with a field strength meter and play with the angles. You could even cut the radiator longer to start with and trim off a little bit at a time for a peak in RSSI .
Aspite some very negative comments i concider this video very informative and well explained! The impedance matching is very important, also the SWR measurement. A NanoVNA ist probably the best and quite inexpensive tool to tune an antenna. Why is a dipole antenna 37 ohm? Is this true for all frequencies and idenpendent from heigt and form/surroundings of the antenna?
Thanks for the video. Why 234 vice the 300 for c that they teach in the books? it is clear to see that 234 used in the equations works well. Thanks again for the video and for your time.
Plz answer my questions ASAP. I want to know do there is a antenna tht very tiny something like 10^(-3) m, with very narrow beam reaching inosphere. beam so narrow tht it rarely expand when reaches inosphere giving pure one to one connection. Explanation was the best and easiest. By now i have this doubt.
This question has probably been answered already. And if it has i apologize. My question is what is the purpose of a capacitor being installed on the inside of a flexible antenna? If this seems to be a stupid question i apologize. I'm not stupid but I'm definitely not a genius either. I absolutely love trying to figure out how things work. I love to find things that don't work and see if i can figure out what is wrong with it then see if I can fix it.
What would be the purpose of a 5 director, powered yagi antenna on an easement? I.e. maintained by county? It's approximately 10' off the ground about 1/4 mile from a cell tower
Nice job. According to the formula we see towards the end of the video, when we calculate low frequencies, the wire sizes are quite long. For example; 2832 inch for 1Mhz frequency. An impossible length. Is there a way to shorten the wire sizes?
Nice tutuorial but would have been better if he had actually hooked it up to a radio and a meter to demonstrate the actual values he was explaining . I did this very stunt back in 1972 when I came back stateside and boughty my first CB radio. I worked with guys who were antenna specialist in AF and we used to play with antenna designs to see if it was possible to take old military antenna and addapt them to Civilian usage for fun. Some interesting experements and drove the FCC crazy at times.
For the antenna shown at 6:39, would be ok to use something like Plasti Dip compound to protect it from elements? I mean, would sillicone decrease the effectivity of the antenna? And BTOH, would sillicone be conductive enough to short main pole and ground poles?
I have used Humiseal conformal coating with success but you would have to check if Plasti Dip is conductive. Check out this video at about minute 6 where I test the antenna with a VNA. You would have to do a before/after measurement to see if VSWR increases or Impedance changes after Plasti Dip is applied. ua-cam.com/video/wR-2c8VgunI/v-deo.html
@@0033mer Excellent, thank you. I think PlastiDip is vinil, I would not care on an audio circuit but I have no idea how would it behave at 500-600MHz. So I will follow your indications (although I think I wont be able to measure high freq stuff with my equipment)
Hey, I have been watching every single possible video on antenna tuners that I can find in order to understand everything I can about this devices, I have a modem receiver that have this single wire antennas that come with a ATU unit "Two of them" each have a this totally miniaturized version of it.. but range on this particular unit really stinks. Now its my hope to increase the range by installing a good set of choked dipoles but don't know if I have not other choice but to use the same type of ATU? with the same value on the capacitors & inductor....your advice will mean the world to me!!
Start out simple. Go through the instruction manual that came with your tuner. Feed your single wire antenna into the tuner. Make sure you have a good ground ... very important. The impedance of the single wire will be high so the tuner matches it to the 50 ohm radio connection. Use an antenna analyzer during tuning to get a low VSWR which will verify the match. Get in contact with your local Ham club if you need more help. Check out this video that describes a very simple setup: ua-cam.com/video/o43sAF4HwJs/v-deo.html
I'm very grateful for your advance, thank you very much.. but what I was really asking was.. since the one wire are already tuned by the manufacturer.. and have such a short range would I have to use exactly the same tuning circuit when I connect it to a dipole? ore will I have to use a different circuit....or slightly different... ?
A Dipole is a resonant antenna so you need to cut its length to 1/2 wavelength at the desired operating frequency. Use a SWR antenna analyzer to find the resonant frequency and fine tune it so you can feed it directly into your radio. If you do not have any test equipment feed it to your same tuning circuit and then your radio.
Yup, I do have the means to make my own custom antennas and I will be using probably a 1/4 wave, my true problem is my ignorance of that if I remove the tuning circuit... I may literally destroy my receiver.. "Since been a modem there is some data exchange... goes in both direction" that is what is digging a hole in my head, that is the reason I'm trying to find a few fellow amateur radio friends that can guide and help me, thank you very much from Daytona beach KN4GCQ
How did you know to bend your 4 prongs down 45°? If you were trying to verify your 50ohm would you hook it up to a multimeter or a scope or some other device?
You would adjust the antenna for minimum VSWR or maximum (db value ) return loss at the operating frequency. A VSWR value lower than 2:1 or a return loss greater than 10 db is what you want. Any device capable of measuring VSWR or return loss can be used, and tune for best results.
Hi, I want to make an external quarter wave ground plane antenna, mainly to monitor frequencies 118.000 MHz to 136.975 MHz (aircraft band). As far as the 3mm welding rod is concern, is bronze better than aluminum? Also, when using the antenna calculator to determine the length of the radiating element and radial elements, what frequency will I input in the calculator and will I retain the 0.95 velocity factor?
BNC pin is the worst choice for an antenna. Its quicker but offers poor and unstable conductivity. 377 ohms for free space???. Kindly clarify if that is for the frequency of the signal in discussion. What frequency is that?
It is the characteristic impedance of free space similar to the character impedance of a coaxial cable which is independent of wavelength. It is the relationship of the electric field (capacitance) and the magnetic field (inductance) in free space. For air it is 377 ohms.
@@0033mer thanks for the reply. However my basic doubt is if the freespace has only 377 ohms then how are we not electrocuted near high voltage pylons or powergrids or say even the feeder lines carrying 11000 voltage. Kindly clarify
I don't think you understand "characteristic"" impedance and confusing it with resistance. You need to go online and study transmission line theory. In my short 10 min video I am simply stating an antenna is a impedance transformer from 377 to 50 ohms. www.ad5gg.com/2018/09/25/what-is-characteristic-impedance/
@@0033mer thanks a lot. I really enjoyed your creative writing which makes complex things easier to understand. From an application point of view how does this 377 ohms play a role. Does it determine attenuation of RF signal in free space and or its the impedance matching thing between the antenna and the freespace or in what manner it must be considered.
I am building two antennas for a LoRa project (915 Mhz ) Watch for the video. 915 Mhz the wire lengths are: 7.9 cm 433 Mhz the wire lengths are: 16.6 cm
Great video, but question- how the heck do you get 50 ohms coming out of the radio- I thought ohms was a measure of resistance to current, not something that flows.
When we say the radio has a "50 ohm output" we are talking about an "impedance" ( AC resistance ) which cannot be measured with an ohmmeter. It has resistance and reactance and is frequency dependant. This means the radio's power output is optimized when driving a 50 ohm load. A proper transmission line and antenna as the load will ensure this will happen.
0033mer thanks! I'll chew on that. I guess it's sort of like electrical AC "inertia," or sort of like how power plants have a certain resistance across their generators, or like how transmission lines are storing and cycling through reactive energy which is stored in the region around the lines in an inductive manner. And I suppose it has something to do with the power getting radiated properly at the antenna rather than reflecting back to the radio station.
I found this from the Practical Antenna Handbook- "The impedance of the half-wave antenna usually is considered to be the imped- ance as seen by the transmitter at the input terminals. This impedance consists of both resistance and reactance. If the antenna is cut to a length of exact resonance, the reactance is zero and the impedance is purely resistive. However, if the antenna is longer or shorter than resonance, reactance is present. When the antenna is made shorter, capacitive reactance is present; when the antenna is made longer, inductive reactance is present. The impedance at the antenna input terminals is important in terms of power ef- ficiency. If the transmitter is feeding a nonresonant antenna, a power loss is caused by the reactive component of the antenna impedance. Conversely, if the frequency of the transmitter is changed, the electrical length of the antenna also changes. If the frequency is made somewhat higher, the electrical length is made greater, and in- ductive reactance is added to the impedance. If the frequency is lowered, the elec- trical length is shortened, and capacitive reactance is added to the impedance."
Great video. I’ve been a ham for a long time, but this really helped me grasp some of the fundamentals of impedance matching better. My one complaint-I’m American, but I use metric for anything technical. As soon as you started using inches I got discouraged.
That’s a weird suggestion. You want me to try to use my phone’s calculator while watching the video on it and also be able to concentrate on the subject matter? My 7th grade teacher emphasized a method of getting comfortable with Metric. I embraced it and it’s served me well. Don’t convert. Measure in metric and just use that. For most day-to-day stuff, you’re approximating. See a quart of of milk? Think of it as a liter. See a measure of 100 meters and think of it as about the size of a football field. 2 liter bottle? That one is easy. :) I can never keep dry ounces and liquid ounces and weight ounces and 5/16 screws and acres and 3/4 miles all in order. So I look on the package for the metric values and do everything that way. Sooooo much easier than trying to convert Imperial tablespoons to cups. An M3 screw is 3mm and an m4 screw is 4mm. Is a 5/16” screw larger than a 3/4”? Let me find a common denominator. Or maybe just divide to get a decimal inch equivalent. Maybe that’s why it seems okay to use a calculator to people used to imperial units. You’re used to that overhead. If you usually use metric, then it’s just weird to not be able to shift a decimal and get a matching unit. In science we’ve moved on. I learned Earth acceleration due to gravity as 9.8 m/s/s, with 10 being good enough for many purposes. Many of my peers struggle with 32 ft/s/s. See who gets bogged down more quickly. But I get that the US politicized the change and we are still an imperial nation. I don’t care of other people are happy using it. However, in any US science or technical discussion, I expect to hear both. If you have a layperson (non-scientist) US UA-cam audience, it’s rude to just give metric values. The US audience is going to miss the gist or tune out. You should know your audience and accommodate their special needs. Many Europeans know non-tech people in the US are a big part of their audience, so they commonly make the effort to have both. But it’s just weird (and a bad look) to not include metric, the lingua Franca of science, at all. To the suggestion that I stop watching the video because I don’t like the units? Did you not see that my main message was that I loved the video and got a lot out of it. It’s exceptional. I just found the lack of metric units made it harder to understand the subject matter. Sorry so lengthy. I just was annoyed to be poked by two people over a simple suggestion tacked on to a complement. It was a waste of my time and anyone else who reads this thread! My apologies
101?! Listen to yourself! This presentation is jam-packed with jargon and upper - level knowledge. "We can see that all the power is coming off...perpendicular to the antenna." I don't know who this "we" is. Do you gotta mouse in your pocket? I see a bagel.
If you feel this video is jam-packed with upper level knowledge then start off with with other Antenna Basic videos available on UA-cam to get you up to speed. ua-cam.com/video/FaCYojMScaU/v-deo.html
Any electronic supply store that sells RF connectors should have them. You can also check online. www.rpelectronics.com/184-515-1-n-female-chassis-mount-with-flange.html shop.mroelectronics.com/mro/product.php?id_product=1140 www.amazon.com/female-connector-chassis-Quality-Shipping/dp/B01CWJ4DA4 www.ebay.ca/itm/N-female-Jack-4-Hole-panel-Mount-Chassis-with-solder-cup-RF-Coaxial-Connector/272360374545?hash=item3f69f18111:g:XucAAOSwH3NXnxOS:rk:1:pf:0
A 1/4 wave monopole ground plane antenna is a unity gain antenna (0dbd) when compared to a 1/2 wave dipole. When compared to an isotropic antenna it has a gain of 2.15 dbi. Using a unity gain ground plane antenna you will get a about a 6 db increase over a rubber duckie (helical) antenna. A rubber duckie is very inefficient, it is basically an attenuator. It is a compromise between gain and small size.
Radio waves follow an inverse square law for power density. The power density is proportional to the inverse square of the distance. Every time you double the distance, you receive only one-fourth the power. This means that every 6-dBm increase in output power doubles the possible distance that is achievable. Double the range = 4 times the power and every 3db is double the power. This is a basic rule of thumb of antenna gain. www.amalgamate2000.com/sales/2.htm
You started off well and then made the error. The power per unit area of RF power falls as the square of the distance. The gain is dB which is a ratio of power in this case, it is a doubling of the power. Hence the range goes up by sqrt(2)
Yes ... you are correct, on doubling the power the range goes up by the square root of 2 which is 1.41 In this case the gain is 6db which is a power ratio of 4, and the square root of 4 is 2 ... which is double the distance. I think you are confusing voltage ratio with power ratio.
The connector has to be silver plated for the solder to take. A connector made by Amphenol will work but a knock-off will not. Here is a video with a solution. ( starts at minute 3 ) ua-cam.com/video/JeUexihrKZQ/v-deo.html
I have forgotten, an N connector is 50 ohms. What is a BNC? BTW, ever play with the angle of the ground plain to see the impedance? Ever play with different copper wire? (could be the oxygen content) Ever use a capacitor for matching purposes? Ever ground your rig using a copper pipe or many small ones over a large distance? All of it makes a difference.
Take a 12 volt battery and connect a 50 ohm resistor in series with it. Put the components in a box and bring out the two leads to terminal posts. Connect a 25 ohm resistor across the terminals and measure the power dissipation in the resistor. Do the same for a 50 and 75 ohm resistor. Which resistor dissipates the most power? ( Use Ohm's law ) How much power was dissipated?
The 50 ohm resistor will dissipate the most power (.72 Watts ) because it matches the output impedance of the source voltage supply which will result in maximum power transfer. This is high school electronics.
I know this is an older video but SO HELPFUL. Super informative, easy to understand, not long winded...and amazing use of a bagel to explain a concept! Thank you so much - loved it!
You are so welcome! Thanks for the feedback.
Underrated video! I'm a ham and I wish I had viewed this video when I first started. Thanks for explaining antennas in such an easy way to understand. Keep them coming.
N2FLA...
Agreed. 6 years later, still underrated. It's not exactly a master-class, but it hits the important pieces for getting 90% there, which is better than watching a master-class for hours, missing most of the concepts, and trying to apply them to get a workable antenna. One formula, and a simple modable design.
I didnt understand shit... I think im too young
I got my FCC First Class RT Operator license in 1980, but antennas were always a weak point for me. This video bought a lot back, and made a lot clear to me. Nicely done, sir.
Thanks for the feedback ... glad it helped!
Please make more antenna videos! You just explained to me in 8 freakin minutes what no one else has explained to me in 20 years of casual investigation. PHYSICAL demonstrations of the antenna wiring beat every damn virtual/whiteboard drawing EVERY DAY.
THANK YOU SIR! I finally actually understand WTF a dipole antenna actually is, in real life...
Oh, and YEAH, what the ground plane stuff is for also!!!!
73, KD2OQN
Glad I could help.
@@0033mer how did you learn this when many of us have struggled for years trying to get our heads wrapped around how an antenna functions?
I became clear to the concept of impedance matching after watching this video after listening to the word almost for 6 years without any logic. Wow dude... you did great.
I've watched many videos over time, read books, but have never understood my CB antenna(s), I'm not stupid, I just never found one that made sense, so I was happy to follow the rule that as long as I could get the SWR below 1.5 by adjusting the length of the 'top' part, it was good!.
This video made some sense, it helped me understand concepts I wasn't sure about. The way the power is radiated, how and why the cable can be as long as the aerial, but that it's the shield that reflects the power from the center back into itself, split the two, go opersite ways and you've got less reflection, split the shield part further and you get a ground plane, So simple it actually made sense rather than the drawing in books of a upside down triangle!
My D-Pole was the best by far, 10mls, and when there was 'skip' I got to chat to people in other countries! But, OMG! I actually have some understanding now!
Seriously, this is like the basic 101 that I needed to kick my ass into gear in to wanting to learn and understand this topic rather than just getting the lowest SWR, I hope now to be able to look for another video or wait for you to produce one which can explain CB antennas, base loaded, mag mount vs through hole grounded, you really did a amazing video there... not too much maths, just enough to help... Thank you soooooo much!
Well explained. Demo much easier to understand than other videos. Good job
Glad it was helpful!
Using a bagel to describe a radiation pattern is super clever.
bagelectrical 101
Very Large Bagel 👍😆
Now I know why pigs love ham radios! Think of all those calories!!! S#1t!
reverse thrust very good question, he probably likes ham radio too.
He certainly used his loaf ;)
Excellent description of the EM field generated by the monopole and dipole, as well as gain antennas! Great use of visual aids!
Hello Sir - very nice demonstration and explanation. Just one slight correction I would humbly offer: around 2:40 you refer to maximum power transfer from a stereo amplifier to a loudspeaker. This may be the case in vacuum tube designs but in most solid state designs the amplifier is made to behave as a voltage source, and usually has an equivalent output impedance of milliohms. The designation of 4 or 8 ohms you may see on the speaker terminals of an audio amplifier relates to the design limits of the output stage and to the current and voltage capability of the amplifier to deliver its rated power to a load of a given impedance before either running out of current or voltage. Therefore, it does not exactly relate to the typical RF power amplifier or signal generator, where the output impedance is matched to the rated load impedance for maximum power transfer.
Thanks for the response.Yes .. In a vacuum tube amplifier the tubes drive a impedance matching transformer so the speaker load is important for maximum power transfer. These are the days I remember. Solid state class A/B amplifiers are more flexible about speaker impedance and we match more for distortion than power transfer. With the new class D power amplifiers however the output low pass filter needs to see a proper speaker load for power and frequency response. For someone who is new to antenna operation I simply used the stereo speaker output example as something they can relate to.
I just learned more about antennas watching this video, than I did the last couple of years reading forum posts on it... Excellent may I say
Wow, what a fine, clear, imaginative presentation! Best I've seen. You are a gifted teacher!
Thanks for the feedback!
Best explanation of antenna theory ever. 👍 Great job 👏👏👏👏👏
Thanks, appreciate you watching!
I know this is five years late, but that was the best video presentation of antenna pract app. You sir, should write a book, (failing that, at least more videos) expeditiously. Thanks for sharing. KC3UEE
You're welcome! Thanks for the feedback.
Thanks for posting. Very clear explanation. Easy to understand even for a non-native speaker like myself.
Antenna theory is one of the most interesting 'mystery sciences' there is. They just don't work according to 'normal' electrical theory and many people just don't understand that.
This Video REALLY Helped Me To Understand HOW Antennas Work.
Thank you. Very well explained. Especially that you bend the radials to 45 degrees to match the 50 Ohm impedance --- now I get it. Thank you :)
You're welcome. If you want to see that type of antenna on an analyzer check out this video:
ua-cam.com/video/wR-2c8VgunI/v-deo.html Thanks for the visit.
I'm a rf engineer and worked on antenna in the past. Typically when you make an dipole or monopole antenna, you should connect your antenna to a VNA and check your return loss(s11), and make sure it is tuned to the right frequency. The actual size of the antenna is shorter than the calculated value because of fringing effect.
The antenna was trimmed using an Anritsu S412E for best return loss. Fringe fields only apply to Microstrip/Patch antennas. With a wire monopole the Velocity factor (Vf) has to be taken in consideration for proper antenna size. The velocity factor is already taken care of in the formula for constructing the radiator and ground plane radials.
@@0033mer rotflmao ,,,,,, You The Man!!!!!! ,,,,,, I've been reading some of the replies,,,, some of these folks need to check themselves before attempting to check you,,, Thank you for taking them back to school! it's been confirmed, you that guy !!!!!
👍 nice presentation, I like the demonstration using the Donat. But seriously, I like the practical views on how to create a simple antenna.
Glad it was helpful!
This is a gold mine find. Dude. You explained it better than anyone! Are you gonna make more videos where you go into how this also related to antenna math?
Thank you for this informational video! I’m just getting started in Radio Astronomy, but don’t know much about antennas, but this video certainly helps =)
Great explanation on Dipole antennas and the formula are really pertinent. Thanks!!
90 seconds into the video, I already loved the donnut or bagel analogy ! Thanks !
AWE - Video ended too soon :( I was learning so much. --- More videos like this please :D
Check out this video on antenna construction:
ua-cam.com/video/JeUexihrKZQ/v-deo.html
thank you :)
Alright 2 years after the last comment, yes, helpful thank you! Honestly though, when you brought that bagel out, I lost it! and, realized I was on the right channel.
Learning about antennas, also never had a bagel but those look nice
Nicely done, the bagel demonstration was clever. Question: would a Yagi-Uda antenna be effective at focusing a 2.4GHz signal at a distance?
Brilliantly explained sir, just superb. Greetings from Wales (no call sign yet... hopefully in two weeks if I pass) 👍
Thanks for the feedback and good luck with your test!
Many thanks. Can I suggest a video project for you (and for me to copy haha!)... any chance you might be able to do a project that constructs an SWR meter using the Arduino? I am certain this would be hugely popular!
I have built VSWR alarms for repeater systems using a Motorola directional coupler and a microcontroller.
The directional couplers are expensive and tricky if you want to build one yourself.
I would invest in a Bird 43 and learn how to use it properly ... very powerful tool.
Bloody awesome video mate, explained some of the concepts I thought I knew but became so much clearer after watching this, thank you.
Thanks for the feedback ... glad that it helped.
Great video. How does one measure impedance changes as the wires are bent down?
Check out this video around 4:22. ua-cam.com/video/zMjA_s30G2I/v-deo.html
@@0033mer Ah the VNA tool! Thank you!!!!!
Welcome!
Excellent explanation for newbies (like me)!
Glad it was helpful!
That is a very well presented video tutorial. A lot crammed in and every bit relevant. Great work
I tried putting bagels on my antennas and got less power. Will doughnuts improve my transmission or reception? Are crescents any good?
I haven't a clue what you were talking about but it was a well informed clip 👍🏾👍👍🏽
Check out the description box for more instructional videos.
Great description with the bagel.
Glad you liked it!
A really good absolute-beginners antenna video.
You did a great job w this video. Very straight forward and clean explain w a nice practice build
That was really interesting. One point; the radial wires did not look like they where are 45 degrees. More like 30 degrees. I guess you could tune the wires if you have a signal strength meter. Perhaps a smart phone with a WiFi app that shows signal strength. That might make an interesting video. Thanks, I'm enjoying these videos. Short, simple, clear and no frills.
Good observation .. I built a few of these antennas with different radial angles and I happened to use that one in the video.
You are correct, the best way to fine tune the antenna is with a field strength meter and play with the angles.
You could even cut the radiator longer to start with and trim off a little bit at a time for a peak in RSSI .
Robert Shaver
Aspite some very negative comments i concider this video very informative and well explained! The impedance matching is very important, also the SWR measurement. A NanoVNA ist probably the best and quite inexpensive tool to tune an antenna. Why is a dipole antenna 37 ohm? Is this true for all frequencies and idenpendent from heigt and form/surroundings of the antenna?
Thanks for the video. Why 234 vice the 300 for c that they teach in the books? it is clear to see that 234 used in the equations works well. Thanks again for the video and for your time.
Ughhh , like i was back in high school! Very informative
Plz answer my questions ASAP. I want to know do there is a antenna tht very tiny something like 10^(-3) m, with very narrow beam reaching inosphere. beam so narrow tht it rarely expand when reaches inosphere giving pure one to one connection.
Explanation was the best and easiest. By now i have this doubt.
This question has probably been answered already. And if it has i apologize. My question is what is the purpose of a capacitor being installed on the inside of a flexible antenna?
If this seems to be a stupid question i apologize. I'm not stupid but I'm definitely not a genius either. I absolutely love trying to figure out how things work. I love to find things that don't work and see if i can figure out what is wrong with it then see if I can fix it.
Really nice video for complete beginners like myself!
Thank you for an amazingly informative and concise video...so much learned in so short a time!...JR Bristol..UK
Brilliant...! Thanx for making this video, it has cleared up a number of things for me about making antennas...and the VSWR too! :)
5:10 the input impedance will change of you bend the exposed parts to the black (like 120-130 degrees), more like 50 Ω then
Great videos , informative.
Im not so good at electronics and need some help.
I have a Sony AIR-7 Scanner radio with Air ,PSB
Pretty good simplified explanation.
assembled a TV antenna tonight, now I'm here to know how it works
You are so smart. I can remember now because the signal is spread in the pattern of a bagel.:-)
“We’re not creating power, we’re focusing the power”
Excellent presentation. Easily understood. Thanks
Great vid. Gonna try to build a monopole tomorrow.
Do you have a link to buy the chassis mount female connector?
Check out Digi-key, they carry the whole range of RF connectors.
www.digikey.ca/product-detail/en/amphenol-rf/82-97-RFX/ARFX1023-ND/21820
N Connecters are use for both 1200 Mhz and 2400 Mhz Antenna,
Hell yes! Your vids and explanations are the best.
Thanks, i will try to make this kind of antenna for my helium miner
Oh great... another number that I got to remember... 377. However, this is a great video!!!!
What would be the purpose of a 5 director, powered yagi antenna on an easement? I.e. maintained by county? It's approximately 10' off the ground about 1/4 mile from a cell tower
Nice job. According to the formula we see towards the end of the video, when we calculate low frequencies, the wire sizes are quite long. For example; 2832 inch for 1Mhz frequency. An impossible length. Is there a way to shorten the wire sizes?
Low frequency = long antennas. Search online for long wire antennas with balun or antenna tuner.
Nice tutuorial but would have been better if he had actually hooked it up to a radio and
a meter to demonstrate the actual values he was explaining . I did this very stunt back
in 1972 when I came back stateside and boughty my first CB radio. I worked with guys
who were antenna specialist in AF and we used to play with antenna designs to see
if it was possible to take old military antenna and addapt them to Civilian usage for fun.
Some interesting experements and drove the FCC crazy at times.
For the antenna shown at 6:39, would be ok to use something like Plasti Dip compound to protect it from elements? I mean, would sillicone decrease the effectivity of the antenna? And BTOH, would sillicone be conductive enough to short main pole and ground poles?
I have used Humiseal conformal coating with success but you would have to check if Plasti Dip is conductive. Check out this video at about minute 6 where I test the antenna with a VNA. You would have to do a before/after measurement to see if VSWR increases or Impedance changes after Plasti Dip is applied. ua-cam.com/video/wR-2c8VgunI/v-deo.html
@@0033mer Excellent, thank you. I think PlastiDip is vinil, I would not care on an audio circuit but I have no idea how would it behave at 500-600MHz. So I will follow your indications (although I think I wont be able to measure high freq stuff with my equipment)
Great video, thank you for putting it together!
excellent! Thank you very much
You are welcome!
Really interesting info. Thank you for passing it on. Definitely will [subscribe] for more possible tidbits of radio-wisdom :) Thank you again!
Hey, I have been watching every single possible video on antenna tuners that I can find in order to understand everything I can about this devices, I have a modem receiver that have this single wire antennas that come with a ATU unit "Two of them" each have a this totally miniaturized version of it.. but range on this particular unit really stinks. Now its my hope to increase the range by installing a good set of choked dipoles but don't know if I have not other choice but to use the same type of ATU? with the same value on the capacitors & inductor....your advice will mean the world to me!!
Start out simple. Go through the instruction manual that came with your tuner.
Feed your single wire antenna into the tuner. Make sure you have a good ground ... very important.
The impedance of the single wire will be high so the tuner matches it to the 50 ohm radio connection.
Use an antenna analyzer during tuning to get a low VSWR which will verify the match.
Get in contact with your local Ham club if you need more help.
Check out this video that describes a very simple setup:
ua-cam.com/video/o43sAF4HwJs/v-deo.html
I'm very grateful for your advance, thank you very much.. but what I was really asking was.. since the one wire are already tuned by the manufacturer.. and have such a short range would I have to use exactly the same tuning circuit when I connect it to a dipole? ore will I have to use a different circuit....or slightly different... ?
A Dipole is a resonant antenna so you need to cut its length to 1/2 wavelength at the desired operating frequency.
Use a SWR antenna analyzer to find the resonant frequency and fine tune it so you can feed it directly into your radio.
If you do not have any test equipment feed it to your same tuning circuit and then your radio.
Yup, I do have the means to make my own custom antennas and I will be using probably a 1/4 wave, my true problem is my ignorance of that if I remove the tuning circuit... I may literally destroy my receiver.. "Since been a modem there is some data exchange... goes in both direction" that is what is digging a hole in my head, that is the reason I'm trying to find a few fellow amateur radio friends that can guide and help me, thank you very much from Daytona beach KN4GCQ
You are brilliant! Thanks for the video!
Your welcome!
Does the outer metal of the coaxial cable work to isolate the inner one from radio waves while transporting a signal *and* receives radiation?
yes .. that is correct and the physical dimensions of the cable determine the characteristic impedance.
You know what I just liked your video and subscribed you. Thank you.
Absolutely brilliant video.
Thanks for the feedback ..
You're welcome. You really are doing a service in sharing this information.
How did you know to bend your 4 prongs down 45°? If you were trying to verify your 50ohm would you hook it up to a multimeter or a scope or some other device?
You would adjust the antenna for minimum VSWR or maximum (db value ) return loss at the operating frequency.
A VSWR value lower than 2:1 or a return loss greater than 10 db is what you want.
Any device capable of measuring VSWR or return loss can be used, and tune for best results.
Hi, I want to make an external quarter wave ground plane antenna, mainly to monitor frequencies 118.000 MHz to 136.975 MHz (aircraft band). As far as the 3mm welding rod is concern, is bronze better than aluminum? Also, when using the antenna calculator to determine the length of the radiating element and radial elements, what frequency will I input in the calculator and will I retain the 0.95 velocity factor?
BNC pin is the worst choice for an antenna. Its quicker but offers poor and unstable conductivity.
377 ohms for free space???. Kindly clarify if that is for the frequency of the signal in discussion. What frequency is that?
It is the characteristic impedance of free space similar to the character impedance of a coaxial cable which is independent of wavelength. It is the relationship of the electric field (capacitance) and the magnetic field (inductance) in free space. For air it is 377 ohms.
@@0033mer thanks for the reply. However my basic doubt is if the freespace has only 377 ohms then how are we not electrocuted near high voltage pylons or powergrids or say even the feeder lines carrying 11000 voltage. Kindly clarify
I don't think you understand "characteristic"" impedance and confusing it with resistance. You need to go online and study transmission line theory. In my short 10 min video I am simply stating an antenna is a impedance transformer from 377 to 50 ohms.
www.ad5gg.com/2018/09/25/what-is-characteristic-impedance/
@@0033mer thanks a lot. I really enjoyed your creative writing which makes complex things easier to understand. From an application point of view how does this 377 ohms play a role. Does it determine attenuation of RF signal in free space and or its the impedance matching thing between the antenna and the freespace or in what manner it must be considered.
Your writing of envisaging a DC pulse as AC and super multimeter and 100 miles examples are praiseworthy. Please keep educating
Just out of curiosity with antenna this small could it be made in a chip form and be able to pick up over the air channels?
You can etch an antenna on a copper printed circuit board. (PCB)
ua-cam.com/video/JeUexihrKZQ/v-deo.html
0:35 That's what she said, "You're vertically polarized"! Bagel?
Hello, I would like to ask whether this formula can also be used on 433mhz or 915mhz systems.
According to this formula, it has become 1.66 cm at 433mhz and 0.78 cm at 915mhz. Is this correct?
I'm not questioning, I'm just a learner who wants to plead for the answer... Thank you
I am building two antennas for a LoRa project (915 Mhz ) Watch for the video.
915 Mhz the wire lengths are: 7.9 cm
433 Mhz the wire lengths are: 16.6 cm
I am looking forward to watching and learning...
Love your video thanks you got a new subscriber keep them coming
Great video, but question- how the heck do you get 50 ohms coming out of the radio- I thought ohms was a measure of resistance to current, not something that flows.
When we say the radio has a "50 ohm output" we are talking about an "impedance" ( AC resistance ) which cannot be measured with an ohmmeter. It has resistance and reactance and is frequency dependant. This means the radio's power output is optimized when driving a 50 ohm load. A proper transmission line and antenna as the load will ensure this will happen.
0033mer thanks! I'll chew on that. I guess it's sort of like electrical AC "inertia," or sort of like how power plants have a certain resistance across their generators, or like how transmission lines are storing and cycling through reactive energy which is stored in the region around the lines in an inductive manner. And I suppose it has something to do with the power getting radiated properly at the antenna rather than reflecting back to the radio station.
I found this from the Practical Antenna Handbook-
"The impedance of the half-wave antenna usually is considered to be the imped- ance as seen by the transmitter at the input terminals. This impedance consists of both resistance and reactance. If the antenna is cut to a length of exact resonance, the reactance is zero and the impedance is purely resistive. However, if the antenna is longer or shorter than resonance, reactance is present. When the antenna is made shorter, capacitive reactance is present; when the antenna is made longer, inductive reactance is present.
The impedance at the antenna input terminals is important in terms of power ef- ficiency. If the transmitter is feeding a nonresonant antenna, a power loss is caused by the reactive component of the antenna impedance. Conversely, if the frequency of the transmitter is changed, the electrical length of the antenna also changes. If the frequency is made somewhat higher, the electrical length is made greater, and in- ductive reactance is added to the impedance. If the frequency is lowered, the elec- trical length is shortened, and capacitive reactance is added to the impedance."
Great video. I’ve been a ham for a long time, but this really helped me grasp some of the fundamentals of impedance matching better.
My one complaint-I’m American, but I use metric for anything technical. As soon as you started using inches I got discouraged.
Length in Inches X 2.54 = Length in Centimeters
Use a calculator ... there is one on your phone.
You COULD have just stopped watching and closed the video ....
That’s a weird suggestion. You want me to try to use my phone’s calculator while watching the video on it and also be able to concentrate on the subject matter?
My 7th grade teacher emphasized a method of getting comfortable with Metric. I embraced it and it’s served me well. Don’t convert. Measure in metric and just use that. For most day-to-day stuff, you’re approximating. See a quart of of milk? Think of it as a liter. See a measure of 100 meters and think of it as about the size of a football field. 2 liter bottle? That one is easy. :) I can never keep dry ounces and liquid ounces and weight ounces and 5/16 screws and acres and 3/4 miles all in order. So I look on the package for the metric values and do everything that way. Sooooo much easier than trying to convert Imperial tablespoons to cups. An M3 screw is 3mm and an m4 screw is 4mm. Is a 5/16” screw larger than a 3/4”? Let me find a common denominator. Or maybe just divide to get a decimal inch equivalent. Maybe that’s why it seems okay to use a calculator to people used to imperial units. You’re used to that overhead. If you usually use metric, then it’s just weird to not be able to shift a decimal and get a matching unit.
In science we’ve moved on. I learned Earth acceleration due to gravity as 9.8 m/s/s, with 10 being good enough for many purposes. Many of my peers struggle with 32 ft/s/s. See who gets bogged down more quickly.
But I get that the US politicized the change and we are still an imperial nation. I don’t care of other people are happy using it. However, in any US science or technical discussion, I expect to hear both. If you have a layperson (non-scientist) US UA-cam audience, it’s rude to just give metric values. The US audience is going to miss the gist or tune out. You should know your audience and accommodate their special needs.
Many Europeans know non-tech people in the US are a big part of their audience, so they commonly make the effort to have both. But it’s just weird (and a bad look) to not include metric, the lingua Franca of science, at all.
To the suggestion that I stop watching the video because I don’t like the units? Did you not see that my main message was that I loved the video and got a lot out of it. It’s exceptional. I just found the lack of metric units made it harder to understand the subject matter.
Sorry so lengthy. I just was annoyed to be poked by two people over a simple suggestion tacked on to a complement. It was a waste of my time and anyone else who reads this thread! My apologies
101?! Listen to yourself! This presentation is jam-packed with jargon and upper - level knowledge. "We can see that all the power is coming off...perpendicular to the antenna." I don't know who this "we" is. Do you gotta mouse in your pocket? I see a bagel.
If you feel this video is jam-packed with upper level knowledge then start off with with other Antenna Basic videos available on UA-cam to get you up to speed. ua-cam.com/video/FaCYojMScaU/v-deo.html
Where do I get the type of connector shown in this video?? Can't seem to find them anywhere
Any electronic supply store that sells RF connectors should have them. You can also check online.
www.rpelectronics.com/184-515-1-n-female-chassis-mount-with-flange.html
shop.mroelectronics.com/mro/product.php?id_product=1140
www.amazon.com/female-connector-chassis-Quality-Shipping/dp/B01CWJ4DA4
www.ebay.ca/itm/N-female-Jack-4-Hole-panel-Mount-Chassis-with-solder-cup-RF-Coaxial-Connector/272360374545?hash=item3f69f18111:g:XucAAOSwH3NXnxOS:rk:1:pf:0
Excellent explanation! Thanks!
You had me at 1:08
Thanks for making this video.
Great video. Thank you..
You're welcome.
Is there an animated video showing what the RF is doing?
Check out this link:
ua-cam.com/video/ozeYaikI11g/v-deo.html
But ground plane antennas don't have any extra gain?
A 1/4 wave monopole ground plane antenna is a unity gain antenna (0dbd) when compared to a 1/2 wave dipole.
When compared to an isotropic antenna it has a gain of 2.15 dbi.
Using a unity gain ground plane antenna you will get a about a 6 db increase over a rubber duckie (helical) antenna.
A rubber duckie is very inefficient, it is basically an attenuator. It is a compromise between gain and small size.
This is pure gold.
btw could this antenna work on other frequencies?
ua-cam.com/video/JeUexihrKZQ/v-deo.html
Great video!
Glad you enjoyed it
No bagels were actually harmed in the making of this video.
6dB doesn't double your range. Remember RF power (like light) falls as distance squared.
Radio waves follow an inverse square law for power density. The power density is proportional to the inverse square of the distance. Every time you double the distance, you receive only one-fourth the power. This means that every 6-dBm increase in output power doubles the possible distance that is achievable. Double the range = 4 times the power and every 3db is double the power. This is a basic rule of thumb of antenna gain.
www.amalgamate2000.com/sales/2.htm
You started off well and then made the error.
The power per unit area of RF power falls as the square of the distance.
The gain is dB which is a ratio of power in this case, it is a doubling of the power. Hence the range goes up by sqrt(2)
Yes ... you are correct, on doubling the power the range goes up by the square root of 2 which is 1.41
In this case the gain is 6db which is a power ratio of 4, and the square root of 4 is 2 ... which is double the distance.
I think you are confusing voltage ratio with power ratio.
Yes, but will this lead to twice as many bagels?
Tried soldering the copper wires to that exact same chassis socket. Not working
The connector has to be silver plated for the solder to take. A connector made by Amphenol will work but a knock-off will not.
Here is a video with a solution. ( starts at minute 3 ) ua-cam.com/video/JeUexihrKZQ/v-deo.html
I'm flunking this class... I feel it's basic-ish but there's a lot of physics involved. Back to high school for me.
Wait a dang minute. Did your bagel just identify as a donut?? What had this world come to???
I have forgotten, an N connector is 50 ohms. What is a BNC? BTW, ever play with the angle of the ground plain to see the impedance? Ever play with different copper wire? (could be the oxygen content) Ever use a capacitor for matching purposes? Ever ground your rig using a copper pipe or many small ones over a large distance? All of it makes a difference.
Joe Shmoe
Love the bagel btw
The real mystery is "Maximum power transfer" how do you explain the matching of load to transmitter and why does it matter?
Take a 12 volt battery and connect a 50 ohm resistor in series with it. Put the components in a box and bring out the two leads to terminal posts. Connect a 25 ohm resistor across the terminals and measure the power dissipation in the resistor. Do the same for a 50 and 75 ohm resistor. Which resistor dissipates the most power? ( Use Ohm's law ) How much power was dissipated?
The 50 ohm resistor will dissipate the most power (.72 Watts ) because it matches the output impedance of the source voltage supply which will result in maximum power transfer. This is high school electronics.