I'll be quite honest, antenna building is my least favourtie part of the hobby, but i always enjoy your videos and explanations, feel like I've learned something and look forward to the practical demo. Thanks all your hard work on the amateur radio front, its great how you do nice antenna theory and live broadcasts... dont know how you find the time :D 73 2E0FWE
Ooooh, I like this idea, thanks for sharing! I don’t have an HF antenna yet at all and this looks simple enough and like it might be a good fit for my very small yard.
Very promising figures Tim. I already have some spare 10 and 15m Cushcraft traps and a 7m fibreglass pole. Might give this a go. Looking forward to the next one buddy.
Tim, this looks great! At 4:53 you had me perplexed because the antenna is elevated 1m above ground. I just modeled it and while the SWR is different if you mount at the ground level vs. 1m above gnd, the pattern and the gain remains basically the same. This is because it is 1/2 lambda in length. Looking forward to the follow-up video where this build is placed on the air. KEEP BUILDING! 73 OM
Worked fine with minor adjustments. Mine was too. sharp on 20 metres. I will have another go when time permits, as it is a great solution at one of my sites. :-)
Hi Tim, Once I saw the title on this I was really keen to watch so saved it for my porridge and toast this morning 😊… Great video and I think this is actually my next project! To be honest all my builds have been resonant antennas and for some reason I just can’t get my head around making traps, specifically how to calculate the turns/former, how to actually measure they are correct for the band and finally where to put them…. 😅 Maybe you have this back in your content somewhere, but I have yet to find a really good explanation on traps and how to make them from the beginning to the end, including how to test them for a specific band… Would you be able to point me to this if you’ve already published it, or maybe even consider doing such a video?…. As you would be the best man to describe it! For me for example, this would be a portable antenna to carry up a SOTA summit, so my traps would need to be very light coax or some other trap option lighter than rg58 . I would likely also use it with the tuner then for 40m to give you UK folk some chaser points too! 😊
Hi Dave - I can point people to how to make the traps - I also have a n idea for a 20/40m dual bander which does need radials but no tuner if that would help?
@@timg5tm941 yep, the 40/20 would be perfect for sota/wwff in my case... expecially if i can get it up with the 7m sotabeams pole. On the traps, yes id love to see the process of making a trap from start to finish, through an example antenna build... Im also interested in loading coils too, particularly to load a shorter wire for 40m portable.
wow I love it can you tell me about the traps please former size and turns would have been helpfull , I like building antennas and seeing what i can do with regards to vswr , is there a plan for it ? cheers VK5OVT , 73
I was wondering: Isn't the 10m Trap drastically lowering the 20m efficency because it is placed close to the 20m current maximum and thereby working against a relative low impedance from the 20m point of view? Even a high Q trap for e.g. 28mhz still has arround 7db attenuation againts 50ohm. Is that something to concern or have i made a mind mistake?
I used to think this, but Cebik produced a paper which outlined that placing coils at the current maximum on a dipole (near centre) only had a fractional reduction in efficiency compared with midway down each leg. This contrasts with a ground vertical where the interaction with the ground itself is what makes a coil near the current maximum the big issue compared with loading the antenna away from the current maximum. The same applies here as the efhw current maximum is well above ground Level so it behaves more like a dipole than a 1/4 wave ground fed.
@@timg5tm941 I need to check out this paper. I am not 100% sure if one can simply apply the findings for a coil to a trap. Even though those coax traps look like a coil they are in fact a well defined parallel LC circuit having a super high impedance at resonance. Intuitively i would place them as far away as possible from the current maximum of any band i want to use the antenna on. But as mentioned i might be totally thinking in the wrong direction :). Need to do more research on this topic. Thanks for sending me down this rabbit hole ;)
What LC values did you add yo MMANA for the traps, I’ve worked them out but they don’t seem to work the lengths in the design. 28.5 1.5uH 20pF 21.2 2uH 27pf
I'll be quite honest, antenna building is my least favourtie part of the hobby, but i always enjoy your videos and explanations, feel like I've learned something and look forward to the practical demo. Thanks all your hard work on the amateur radio front, its great how you do nice antenna theory and live broadcasts... dont know how you find the time :D 73 2E0FWE
You are very kind Al! It’s a very enjoyable hobby!! 73 mate
Ooooh, I like this idea, thanks for sharing! I don’t have an HF antenna yet at all and this looks simple enough and like it might be a good fit for my very small yard.
Glad it was helpful!
Very promising figures Tim. I already have some spare 10 and 15m Cushcraft traps and a 7m fibreglass pole. Might give this a go. Looking forward to the next one buddy.
Thanks mate!
Tim, this looks great! At 4:53 you had me perplexed because the antenna is elevated 1m above ground. I just modeled it and while the SWR is different if you mount at the ground level vs. 1m above gnd, the pattern and the gain remains basically the same. This is because it is 1/2 lambda in length.
Looking forward to the follow-up video where this build is placed on the air. KEEP BUILDING! 73 OM
Thank you sir!
Worked fine with minor adjustments. Mine was too. sharp on 20 metres. I will have another go when time permits, as it is a great solution at one of my sites. :-)
Good luck!
Awesome job Tim 👍
Thanks Ape!
Looking forward to seeing it in action!
Video is out!
Hi Tim,
Once I saw the title on this I was really keen to watch so saved it for my porridge and toast this morning 😊…
Great video and I think this is actually my next project!
To be honest all my builds have been resonant antennas and for some reason I just can’t get my head around making traps, specifically how to calculate the turns/former, how to actually measure they are correct for the band and finally where to put them…. 😅
Maybe you have this back in your content somewhere, but I have yet to find a really good explanation on traps and how to make them from the beginning to the end, including how to test them for a specific band…
Would you be able to point me to this if you’ve already published it, or maybe even consider doing such a video?…. As you would be the best man to describe it!
For me for example, this would be a portable antenna to carry up a SOTA summit, so my traps would need to be very light coax or some other trap option lighter than rg58 .
I would likely also use it with the tuner then for 40m to give you UK folk some chaser points too! 😊
Hi Dave - I can point people to how to make the traps - I also have a n idea for a 20/40m dual bander which does need radials but no tuner if that would help?
@@timg5tm941 yep, the 40/20 would be perfect for sota/wwff in my case... expecially if i can get it up with the 7m sotabeams pole.
On the traps, yes id love to see the process of making a trap from start to finish, through an example antenna build... Im also interested in loading coils too, particularly to load a shorter wire for 40m portable.
@@IrishHamRadio right that’s on the list 👍
Excellent idea Tim. Could a third trap be added to get 17m? Or substitute the 15m trap for a 17m?
Yes you could substitute it. Perhaps 17 could be added? Might be worth a look!
@@timg5tm941 I need to learn how to model that!
@@M0JSX happy to help mate
We could have an antenna which is 50% traps...I wonder how having traps for all the bands would affect 20m?
👍👍
Ta!
Hi Tim. What are the traps details? How many windings, wire diameter, pipe diameter? Thanks. Pavol
wow I love it can you tell me about the traps please former size and turns would have been helpfull , I like building antennas and seeing what i can do with regards to vswr , is there a plan for it ? cheers VK5OVT , 73
Hi Richard - I can look into a video on trap designs. I might pop a link to more info on my community tab on youtube too.
I was wondering: Isn't the 10m Trap drastically lowering the 20m efficency because it is placed close to the 20m current maximum and thereby working against a relative low impedance from the 20m point of view? Even a high Q trap for e.g. 28mhz still has arround 7db attenuation againts 50ohm. Is that something to concern or have i made a mind mistake?
I used to think this, but Cebik produced a paper which outlined that placing coils at the current maximum on a dipole (near centre) only had a fractional reduction in efficiency compared with midway down each leg. This contrasts with a ground vertical where the interaction with the ground itself is what makes a coil near the current maximum the big issue compared with loading the antenna away from the current maximum. The same applies here as the efhw current maximum is well above ground Level so it behaves more like a dipole than a 1/4 wave ground fed.
@@timg5tm941 I need to check out this paper. I am not 100% sure if one can simply apply the findings for a coil to a trap. Even though those coax traps look like a coil they are in fact a well defined parallel LC circuit having a super high impedance at resonance. Intuitively i would place them as far away as possible from the current maximum of any band i want to use the antenna on. But as mentioned i might be totally thinking in the wrong direction :). Need to do more research on this topic. Thanks for sending me down this rabbit hole ;)
Another very interesting ant tim, do you think ,there is any advantages adding a heap of radials on this type of ant. 73
It doesn't need it with the Unun at 49, or 64 to 1, but there is no reason not to try it just for fun. Experimentation should be encouraged. 🙂
Nothing compared with adding radials to a quarter wave. I’m doing a video on that one soon
What LC values did you add yo MMANA for the traps, I’ve worked them out but they don’t seem to work the lengths in the design. 28.5 1.5uH 20pF 21.2 2uH 27pf
Very interessant 👏🏻👏🏻👏🏻
Glad you think so!
I would like to see the coil winding data. G7VFY
Standard coax traps both tuned to just below each band.
@@timg5tm941 do they have to be coax? I want to add two switches or jumpers to get 17m and 12m.
@@G7VFY nope don’t have to be
OK. Understand everything but what a "trap" is. Do you buy these? Make them?
I bought mine - search for coax traps. Lots of stuff online.