Search found 209 matches

by Andrew (grayhat)
Fri May 09, 2025 7:47 pm
Forum: General Discussion
Topic: Another approach to the EFHW
Replies: 0
Views: 2529

Another approach to the EFHW

And one which may fit portable operations ,(SOTA/POTA/...)

I'm referring to the ideas by AA5TB found here

https://www.aa5tb.com/efha.html

which are really good (notice the "tuned" 49:1)
by Andrew (grayhat)
Fri May 09, 2025 7:27 pm
Forum: General Discussion
Topic: Simple beam antenna - the G4ZU "Jungle Job"
Replies: 6
Views: 81967

Re: Simple beam antenna - the G4ZU "Jungle Job"

boom and mast don't influence the radiation pattern so they can be conductive; a way to make the "JJ" portable is to mske it foldable; let's start from.the drawing and change it so that the reflector arms can telescope and may be unlocked and fold toward the antenna front (along the boom) ...
by Andrew (grayhat)
Sat May 03, 2025 8:39 am
Forum: General Discussion
Topic: Greetings from SE Virginia
Replies: 1
Views: 5334

Re: Greetings from SE Virginia

Welcome to the QRPer forum pick a seat and enjoy your stay; a question; you wrote about rig, but rig won't work without an antenna, which antennas fo you use/prefer ?
by Andrew (grayhat)
Wed Apr 30, 2025 2:15 pm
Forum: Questions & Advice
Topic: Oblong loop formulas
Replies: 0
Views: 16892

Oblong loop formulas

the antenna is similar to the one described here https://qrper.com/2023/11/a-portable-oblong-antenna-for-2-meters/ the calc formulas (in meters) are Lambda=300/MHz perimeter=Lambda*1.05 semip=perimeter/2 shortside=semip/3 longsidd=semip-shortside the antenna offers low takeoff angle and a gain over ...
by Andrew (grayhat)
Thu Apr 17, 2025 12:00 pm
Forum: General Discussion
Topic: RF Weapon
Replies: 0
Views: 13524

RF Weapon

by Andrew (grayhat)
Tue Apr 15, 2025 5:16 pm
Forum: General Discussion
Topic: Simple beam antenna - the G4ZU "Jungle Job"
Replies: 6
Views: 81967

Re: Simple beam antenna - the G4ZU "Jungle Job"

as for the multiband version, it uses a trapped dipole (straight) snd a reflector for each band made using wire
performance is below the one from the monoband version
by Andrew (grayhat)
Tue Apr 15, 2025 12:16 pm
Forum: General Discussion
Topic: Simple beam antenna - the G4ZU "Jungle Job"
Replies: 6
Views: 81967

Re: Simple beam antenna - the G4ZU "Jungle Job"

Interesting, I'd never processed that the "Jungle Job" version has an angled driven element. I've previously built a G4ZU beam with a straight driven element and bent reflector. (In fact, on the G4ZU tribute page, that description is used, even though the figure shows the reverse!) An int...
by Andrew (grayhat)
Fri Apr 04, 2025 9:52 pm
Forum: Questions & Advice
Topic: NVIS and antennas
Replies: 0
Views: 40261

NVIS and antennas

zome interesting and useful informations https://practicalantennas.com/applications/nvis/ notice that the observations at the above link also apply to several antennas with horizontal polarization not just dipoles and then, this map https://practicalantennas.com/wp-content/uploads/2023/01/Dipole-Azi...
by Andrew (grayhat)
Fri Apr 04, 2025 9:26 pm
Forum: General Discussion
Topic: Simple ATU
Replies: 5
Views: 108008

Re: Simple ATU

The Fri-Match is derived fron the Z-match, full story here

https://www.pa0fri.com/ATU/FRImatch/FRImatcheng.htm

:)
by Andrew (grayhat)
Tue Apr 01, 2025 7:47 pm
Forum: General Discussion
Topic: Simple ATU
Replies: 5
Views: 108008

Re: Simple ATU

also see

https://www.hamradiosecrets.com/homebre ... tuner.html

although the links at previous post carry all the needed infos