Moving the feedpoint changes the impedance because you're touching the radiating element at different places along its standing wave. Whoah! That never clicked before, thank you.
I use wireless mictrophones (~500-600MHz). The first 5 minutes were great for me. The first time I have understand how impedence on a half wave antenna works. Thanks!
3:48 your calculations are correct. The antenna is resonant also on odd multiples of the lowest band (80m). But(!..) the wire is resonant on odd multiples of a quarter wavelength in these cases, so the impedance at the end of the wire is low. (It behaves like a quarter wave radiator, extended by a half or full wavelength of wire) That means, the transformer won’t work for the odd multiple frequencies. Later in the video, when you are building the antenna for 40m and multiple wavelengths you happen to hit only even multiples. So it works in the end.
Thank you so much for the comment. The antenna I built was ~65 ft long, ie. half wave for 40 m. It resonants at 40 m, 20 m, 15 m, and 10 m. If you build an 80 m antenna (130 ft long), it will resonant at even and odd freq, ie. 80 m, 40m, 30m, 20m, 17m, 15 m, 12m and 10m. Here is a commercial version myantennas.com/wp/product/efhw-8010/ See the SWR graphs. 73, Paul
@@W2PAK Sure, in your configuration the antenna works for 40, 20, 10 and probably on 12m too. I also use this configuration with good success. On the antenna you quote, an inductor is inserted into the wire to make it work on more bands. Only a wire, long enough for 80m will not work for all bands including the odd multiples. I work around this by using different wire lengths for e.g. 10-20m, 40-80m. Keep on experimenting. EFHWs are great! 73 DB6YC
It’s an awesome content . Love it . Have my ham radio license in 1987 . But then came to USA to university and didn’t follow up with ham radio license anymore . Only GMRS and CB for car convoy traveling. I’m thinking about going back to ham radio 😊
Excellent..Many thanks for this superb practical and theoretical presentation..Everything a ‘newbie’ needs to know, without too much embellishment, to get on the air..73..John..G4EIJ
Excellent video, you covered everything and I wish there were more videos like your. Starting build tomorrow since my two cores arrived. Thanks again wd4dda 73
Hi Paul, nice video. I am newly licenced in the UK and just getting into end feed antennas. I found you video both interesting and very helpful with understanding the theory of antenna building. 73's MW7GQB
Welcome to the hobby! I’m glad that the video was helpful to you. Let’s keep an eye open for each other on the bands, it would be fun to chat in person. 73, Paul.
Great video would have talked about antenna height and location of antenna. Many hams live in the city and it's hard to get all the bands with a good enough vswr due to your surroundings. Ty
Great question. You can get them from Amazon, Here is the one I used: www.amazon.com/gp/product/B07Y6NQRGF/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1. You can also get them at stores like DigiKey. 73, Paul
@@W2PAK No tyranny just (technical) literacy. No excuse if you haven't study electronics, you learn that in primary school, and everybody who works with electronics should write correctly (is my humble opinion), especially if you have the ambition of learning the others here on YT or elsewhere. 73! en.wikipedia.org/wiki/Unit_prefix
Thanks for the comment. I thought that the symbol for voltage is "V" in English-speaking countries, but "U" is the standardized international symbol. No?? 73, Paul.
![Quiet Your Rig: Add a Common Mode Choke [Step by Step]](/img/1.gif)
Moving the feedpoint changes the impedance because you're touching the radiating element at different places along its standing wave. Whoah! That never clicked before, thank you.
I am glad you enjoyed. 73, Paul.
I use wireless mictrophones (~500-600MHz). The first 5 minutes were great for me. The first time I have understand how impedence on a half wave antenna works. Thanks!
That is great, I am so glad that it was helpful to you.
3:48 your calculations are correct. The antenna is resonant also on odd multiples of the lowest band (80m). But(!..) the wire is resonant on odd multiples of a quarter wavelength in these cases, so the impedance at the end of the wire is low. (It behaves like a quarter wave radiator, extended by a half or full wavelength of wire) That means, the transformer won’t work for the odd multiple frequencies. Later in the video, when you are building the antenna for 40m and multiple wavelengths you happen to hit only even multiples. So it works in the end.
Thank you so much for the comment. The antenna I built was ~65 ft long, ie. half wave for 40 m. It resonants at 40 m, 20 m, 15 m, and 10 m. If you build an 80 m antenna (130 ft long), it will resonant at even and odd freq, ie. 80 m, 40m, 30m, 20m, 17m, 15 m, 12m and 10m. Here is a commercial version myantennas.com/wp/product/efhw-8010/ See the SWR graphs. 73, Paul
@@W2PAK Sure, in your configuration the antenna works for 40, 20, 10 and probably on 12m too. I also use this configuration with good success. On the antenna you quote, an inductor is inserted into the wire to make it work on more bands. Only a wire, long enough for 80m will not work for all bands including the odd multiples. I work around this by using different wire lengths for e.g. 10-20m, 40-80m.
Keep on experimenting. EFHWs are great!
73 DB6YC
It’s an awesome content . Love it .
Have my ham radio license in 1987 . But then came to USA to university and didn’t follow up with ham radio license anymore .
Only GMRS and CB for car convoy traveling.
I’m thinking about going back to ham radio 😊
Thank you for the kind words and I really hope that you get back to ham radio. I can really be a lot of fun. Hope to catch you on the air. 73, Paul
Excellent presentation, Paul. Well done!
Glad you liked it! 73, Paul.
SIMPLE AND DETAIL EXPLANATION. Thank a lot! "73"
Glad it was helpful! 73, Paul.
Excellent..Many thanks for this superb practical and theoretical presentation..Everything a ‘newbie’ needs to know, without too much embellishment, to get on the air..73..John..G4EIJ
Thanks John, hope to catch you on the air soon. 73, Paul
Excellent video, you covered everything and I wish there were more videos like your.
Starting build tomorrow since my two cores arrived.
Thanks again
wd4dda 73
Thank you for the nice comment. Glad it helped. I hope to chat with you on the air soon. 73, Paul
Just realising the much easier setup with end feds for Pota , great video 😉
I agree! I just went to the beach recently and tried the EFHW, it worked really well with 10W. I made contacts as far Hungary. 73, Paul
Hi Paul, nice video. I am newly licenced in the UK and just getting into end feed antennas. I found you video both interesting and very helpful with understanding the theory of antenna building. 73's MW7GQB
Welcome to the hobby! I’m glad that the video was helpful to you. Let’s keep an eye open for each other on the bands, it would be fun to chat in person. 73, Paul.
Very well explained out to the Newcomers. 💯👍
Thank you so much, I’m glad that you found it useful. 73s, Paul.
Very comprehensive exposition! Thank You! 73 AC8XA
Glad you liked it! 73, Paul.
Nice video! Thanks!
Thank you. Glad you liked it! 73. Paul.
Great video would have talked about antenna height and location of antenna. Many hams live in the city and it's hard to get all the bands with a good enough vswr due to your surroundings. Ty
Thank you of the good comment, that might be a good topic for a future video. 73, Paul
My main antenna in my shack is my 80-10 EFHW at 50 ft.
That is great, it probably works well at 50ft. 73, Paul.
Where would someone buy those toroid cores?
Great question. You can get them from Amazon, Here is the one I used: www.amazon.com/gp/product/B07Y6NQRGF/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1.
You can also get them at stores like DigiKey. 73, Paul
mHz is mili-Herz
No one has ever accused me of being a stickler for capitalization. Perhaps it's a secret rebellion against the tyranny of the upper case, haha. 73.
@@W2PAK No tyranny just (technical) literacy. No excuse if you haven't study electronics, you learn that in primary school, and everybody who works with electronics should write correctly (is my humble opinion), especially if you have the ambition of learning the others here on YT or elsewhere. 73! en.wikipedia.org/wiki/Unit_prefix
😁
@@W2PAK Just a common technical literacy.
That is too much power beeing used. You get very similar results with 3 Watts on a dipole for the 10m band...
I love operating QRP. But I thought 20 W would give this a good test. 73. Paul.
U not V... Basic mistake
Thanks for the comment. I thought that the symbol for voltage is "V" in English-speaking countries, but "U" is the standardized international symbol. No?? 73, Paul.