Dude...I just tried one of these a few days ago, and totally love it too!!! You can learn more about antennas in 45 minutes with a VNA than 10 years of guessing and A/B. Also, I did not yet realize you can click and drag markers. Nice. I was using the "joystick" Fun video!!!!
Great explanation! I'm testing a 9:1 Noo Elec type small balun, and I was expecting to see similar results when measuring it with the Nano VNA from 50KHz to 25MHz. However, with a 470R resistor attached in place of the antenna, the Smith chart impedance readings are far from perfect. They are capacitive before 3MHz and inductive after, with the resistive component dropping. The readings are almost perfect with a 47R resistor though.
The primary purpose of a balun is to match a balanced load to an unbalanced transmission line. In order to accomplish this the balun must present a high common mode impedance. You have not investigated the choking impedance- so what I see you have is a transformer and perhaps a balun- but you will not know until you measure Zcm. It would also be interesting to know what the insertion loss is. Dale W4OP
If you want to look at common mode, you need to analyze the antenna feed point. In this experiment, the load is a not a non resonant load as there is no appreciable reactive component. But looking back from the load towards the transmitter, an X value will be divided by a factor of 4 and the current phase shift can be calculated from that at 50 ohms resistance. It will be roughly constant from 10m through 6m. Cancel (minimize) your antenna X values and common mode currents are minimized. This can be done by changing the antenna dimensions or cancelling the X values through some fixed reactance on the antenna.
It's not a test if you don't check your balun's output: A balun's main job is to match a balanced component with an unbalanced one in an antenna system to avoid common-mode current, a radiating coaxial cable, and distortions in the polar pattern of radiation. Furthermore, you have not checked the insertion losses: about that, how was the compound of the toroids chosen and how was the starting number of the coils calculated? Attention: the magnetic fluxes of those two toroids in that position tend to concatenate
Fantastic video! Congrats on the explanation! I may have missed this information during the video, but which ferrite did you use? I'm doing tests with different types of ferrite and I can't get this performance across the band.
Point of Confusion: When I look at the yellow-trace and the yellow-scale, It looks like you are at 70-Ohms, not 50 as you state; can you clarify? Thank You & 73...
Hello! It's my question that how we can test an antenna for a bipolar monopulse uwb signal for example if that signal has a 5ns width and 100khz repetition..What is the frequency that I have to use as start and stop on nanovna to measure my antenna parameters?????
It would have been nice to see at least the schemat of your 4:1 balun ? as it doesn't look anything like a GUENELLA type 4:1 balun but shows a confusing top toroid used as a rf choke with what looks like more turns on one side than the other !!! over another toroid with an unknown winding. nothing like a gunella balun that does use two torroids but not with a through the middle winding.. Yes i know you don't claim it to be a gunella type balun, but for a 1to 50 mhz balun using two cores of this type, the gunella style is what is commonly used ! and the winding are not un equal or wound in this way.
@@adriansalt4521 I wonder the relevance as well. This was very well presented. You've educated me, thanks. However, I do appreciate well trained female technicians, or male are fine too, but I'd very much like to see girls involved in technology. I have lots of daughters and want them to have good female examples.
Dude...I just tried one of these a few days ago, and totally love it too!!! You can learn more about antennas in 45 minutes with a VNA than 10 years of guessing and A/B. Also, I did not yet realize you can click and drag markers. Nice. I was using the "joystick"
Fun video!!!!
Increadible! Loved this. Can feel your passion for this come through :) Best, Rafi
This is great! I've got a NanoVNA and can now check a homebrew 9:1 unun.
Nicely explained, thanks. Would like to see more like this.
Thank you so much! Will certainly try to make some more!
Please do. This hobby needs more educated videos.
You really should be using carbon comp resistors at RF.
Great explanation! I'm testing a 9:1 Noo Elec type small balun, and I was expecting to see similar results when measuring it with the Nano VNA from 50KHz to 25MHz. However, with a 470R resistor attached in place of the antenna, the Smith chart impedance readings are far from perfect. They are capacitive before 3MHz and inductive after, with the resistive component dropping. The readings are almost perfect with a 47R resistor though.
The primary purpose of a balun is to match a balanced load to an unbalanced transmission line. In order to accomplish this the balun must present a high common mode impedance. You have not investigated the choking impedance- so what I see you have is a transformer and perhaps a balun- but you will not know until you measure Zcm. It would also be interesting to know what the insertion loss is.
Dale W4OP
If you want to look at common mode, you need to analyze the antenna feed point. In this experiment, the load is a not a non resonant load as there is no appreciable reactive component. But looking back from the load towards the transmitter, an X value will be divided by a factor of 4 and the current phase shift can be calculated from that at 50 ohms resistance. It will be roughly constant from 10m through 6m.
Cancel (minimize) your antenna X values and common mode currents are minimized. This can be done by changing the antenna dimensions or cancelling the X values through some fixed reactance on the antenna.
Never heard radio talk sounding hot before!
He's a guy
Great video, thanks
It's not a test if you don't check your balun's output: A balun's main job is to match a balanced component with an unbalanced one in an antenna system to avoid common-mode current, a radiating coaxial cable, and distortions in the polar pattern of radiation.
Furthermore, you have not checked the insertion losses: about that, how was the compound of the toroids chosen and how was the starting number of the coils calculated?
Attention: the magnetic fluxes of those two toroids in that position tend to concatenate
@@someguy782 I wrote a document on this topic. The link is in my page on QRZ site.
It is in italian (sorry) but Google translate will help you.
Fantastic video! Congrats on the explanation! I may have missed this information during the video, but which ferrite did you use? I'm doing tests with different types of ferrite and I can't get this performance across the band.
Point of Confusion: When I look at the yellow-trace and the yellow-scale, It looks like you are at 70-Ohms, not 50 as you state; can you clarify?
Thank You & 73...
Hello!
It's my question that how we can test an antenna for a bipolar monopulse uwb signal for example if that signal has a 5ns width and 100khz repetition..What is the frequency that I have to use as start and stop on nanovna to measure my antenna parameters?????
One Megahertz, not Magahurt. Megahertz is not a plural.
I'm hopeless.... how do I get the resistive reading on the VNA? I've tried every setting!!! Cannot get my screen to look like yours!
What model of Nano VNA do you use?
It would have been nice to see at least the schemat of your 4:1 balun ? as it doesn't look anything like a GUENELLA type 4:1 balun but shows a confusing top toroid used as a rf choke with what looks like more turns on one side than the other !!! over another toroid with an unknown winding. nothing like a gunella balun that does use two torroids but not with a through the middle winding.. Yes i know you don't claim it to be a gunella type balun, but for a 1to 50 mhz balun using two cores of this type, the gunella style is what is commonly used ! and the winding are not un equal or wound in this way.
vk6ysf.com/balun_guanella_current_1-4.htm
what was your core material for this balun?
Cant see the info on screen really ? Swr ? Logmag ? Reactance ? Please show much much closer please
Women?
What's the relevance here?
@@adriansalt4521 I wonder the relevance as well.
This was very well presented.
You've educated me, thanks.
However, I do appreciate well trained female technicians, or male are fine too, but I'd very much like to see girls involved in technology.
I have lots of daughters and want them to have good female examples.