Search found 14 matches

by qrp-gaijin
Mon Oct 17, 2022 5:23 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

as for the CTL, did you consider changing the size of the sides ? I mean, for example, making the vertical size 1/2 of the horizontal (or the other way around) while keeping the same total perimeter I haven't tried this -- what would be the idea behind such a modification? I guess this might encour...
by qrp-gaijin
Mon Oct 17, 2022 5:22 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

Regenerating the loop may be interesting but I think isn't an easy thing, see, if we're using the loop as the "L" part of the regen circuit, we'll need to tune both the antenna and the regen and that will be quite "touchy" and probably the frequency range will be limited (assumi...
by qrp-gaijin
Sun Oct 16, 2022 4:59 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

I'm also curious if the SULA also exhibits a magnetic shadow region in the interior of the loop. I hope to run some simulations soon. There seems to be a very small magnetic shadow effect visible in the SULA. When illuminated from the front (non-null) side by a small vertical dipole located at x=-1...
by qrp-gaijin
Sun Oct 16, 2022 3:23 am
Forum: General Discussion
Topic: Unidirectional, dual-whip E-field antenna
Replies: 0
Views: 11797

Unidirectional, dual-whip E-field antenna

I'm glad to see that there is interest in in the other thread about discussing Villard's old Coplanar Twin Loop Antenna, which generates a "magnetic field shadow" resulting in a unidirectional null. Villard also proposed and tested a dual-whip antenna system that uses an analogous "el...
by qrp-gaijin
Sun Oct 16, 2022 2:52 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

at the moment I'm busy helping some relatives picking olives from trees Very nice! I had the good fortune to visit Italy (Umbria) some years ago and enjoyed taking countryside walks and seeing the local residents harvesting olives. I just had a probably crazy idea, inspired by your loop+dipoles I s...
by qrp-gaijin
Sat Oct 15, 2022 9:02 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

just as a note, if you want to try a circular loop design, the model below is a vanilla circular loop model [...] which could be easily modified (e.g. adding a second, smaller size loop inside Just as a warning, one annoying NEC-2 limitation that we have to be careful about is lining up the segment...
by qrp-gaijin
Sat Oct 15, 2022 8:35 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

My previous magnetic shadow simulations were done with one loop only (the outer CTL loop) to show that the outer loop, by itself, can create a magnetic shadow. But the shadow is not so dark in this case. I found out that when I use the two-loop CTL model (with both the outer high-Z loop and the inne...
by qrp-gaijin
Sat Oct 15, 2022 5:21 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

Did a quick 7 MHz simulation of a CTL over real-ground. Maximum gain is about -22.4 dBi. 7mx.png The outer loop is loaded with 70 ohms of loss resistance to achieve the unidirectional effect. The outer loop is also loaded with 20 uH of lumped inductance to achieve the high-impedance necessary for E-...
by qrp-gaijin
Sat Oct 15, 2022 2:22 am
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

I'm in a hurry, so I'll keep this short; first, that loop and dipoles setup somewhat recalls at large a yagi (dipoles), did you try changing the size/spacing of the dipoles ? Good point. The reason I used 3 fixed dipoles was to have a completely unchanging geometry for the entire test environment, ...
by qrp-gaijin
Fri Oct 14, 2022 3:31 pm
Forum: General Discussion
Topic: Another unidirectional small loop: the Coplanar Twin Loop
Replies: 25
Views: 16231

Re: Another unidirectional small loop: the Coplanar Twin Loop

the impedance is around 2 Ohm which means that, to couple the antenna to a receiver we'll need to use a preamp/buffer designed to accept such low impedance and offering an output impedance around 50 (or 75) Ohms, The CTL article showed a gamma match (tapping at 2 particular locations) on the inner ...