The QRPer Board

check this loop for the 20m band

http://sm0vpo.altervista.org/antennas/20m_ant_00.htm



HTH

And here's the 3D radiation pattern, as you can see, it's just like the one from a regular size dipole
https://qrper.net/download/file.php?id=194

OK, changed the model so that the folded portion is below, so that the contruction/installation of the dipole is easier, here's the new model optimized for the 20 metters band (centered on 14.175 MHz) CM 20m band shortened dipole CM feed it using a guanella 1:1 CE ' design frequency SY freq=14.175 S...

here's a summary, notice the span and the gain

CM shortened dipole CE SY freq=7.100 SY wire=0.0075 SY wave=300/freq SY hfac=0.60 SY lfac=1.2709 SY frac=0.50 SY tlen=(wave*frac)*lfac SY arms=tlen/2 SY hght=wave*hfac SY front=(arms*0.60) SY other=arms-front SY sfac=0.082 SY sides=other*sfac SY back=other-sides SY segs=3 SY segm=21 SY segl=51 GW 1...

Being bored and having some time in my hands I started fiddling with 4NEC2 to explore an idea I had time ago, but let me start from the beginning first of all a fact; if we bend in an U shape the arms of a dipole keeping the "straight portion" (from feedpoint to bend) at 60% of the arm len...

as for gain and pattern let's start with this image https://www.m0pzt.com/cobwebb_plan.jpg as a reference, the main axis of the radiation solid runs from top to bottom of image and, with the antenna placed at 10m height it offers more than 6dBi of gain, the other axis (left-right) offers more than 3...

the activation is ongoing, snd aside some issues wirh FT8, the SSB and CW contacts are just fine. at least looking at the log https://www.mdxc.support/jw0v/log-oqrs/ and the main page carries the updates https://www.mdxc.support/jw0v/ if interested, just start from the log above and the bandplan fou...

suitable for portable operations https://www.m0pzt.com/cobweb-aerial/ and being omnidirectional may be useful for POTA the antenna offers a gain around 6dBi with low takeoff angle and an almost omnidirectional pattern it can be built using stuff found in most "home improvement" stores, so....

next July

https://www.mdxc.support/jw0v/

Vlad OK2WX, will be active as jw0v from Svalbard from 14 to 23 july 2025, 160-6 m, CW/SSB/FT8. QSL via I8KHC

happy hunting

p.s.

there's a bandplan here

https://www.mdxc.support/jw0v/band-plan/