13dka wrote: ↑Wed Jul 13, 2022 12:13 pm
Yes, played with the mode (thanks!) and this looks incredible.
I knew you'd like that; on saltwater or coastal terrain this little loop seems a miracle
The F/B ratio seems to be whopping 20dB minimum above 10 MHz, can also be 30dB elsewhere, of course we're talking losses and not gain here
Sure, but then let's reason a bit; on 40m the NEC models tells we have -43dBi at the front and about -63dBi at the back, if we add a 20dB preamp at the antenna we'll have -20dBi at the front and -43dBi at the back, not bad as front/back and not bad for "setting the S/N" too
all in all, how the LoG and other "lossy" antenna demonstrated, when it comes to receiving, it's all about S/N, and now we have both, S/N and directivity
!
a 3-ele Yagi has typically 13dB or something.
And then, a 3-ele yagi for the 40m (or the 160m) won't be so "portable" and will need to be raised more than just the 3m of this loop
It still wants to fly low but the h/v patters are super consistent and it that works even half as good as the simulation suggests, that would be the receiving antenna you want to stick into the sand on the beach but also the antenna you want to have in the backyard with the back facing your house to eliminate the noise coming from there. Can't wait to have this on the dike!
Well, as I wrote the proof will be "when the rubber meets the asphalt", so at this point I believe it's a matter of waiting and testing, but I'm confident that the antenna will perform as expected; as a note I also ran further experiments, I started by changing the vertical/horizontal ratio of the "cross" and found that, by reducing the horizontal arm size at about 1/3 (and proportionally increase the vertical one), the antenna shows a lower and narrower vertical aperture, but then, the horizontal aperture is widened to about 170° so, I'm not sure such a modification may be worth, I also tried a circular model but that one too doesn't show much improvement, aside from 3dBi more in gain (-40dBi for the round one vs -43dBi for the diamond one), so I think that the diamond shape should be the best compromise
Re junction boxes, that's what all my stuff lives in and I think I'm going to make the "big" version first to have a reference, the profiles I use come in sizes that fit into each other for some telescoping style setup. 2.5mm flexible litz wire should be good to make that contraption foldable so I end up with 1.1m parts still fitting into my trunk.
If you can arrange the "full size" version, go for it, also since simulations were done on that size, so having the real thing will tell how well the model matches the real world antenna, but then again, I think the difference won't be too marked
Another thing I was thinking ... reading the infos floating on the 'net, the Belka receiver seems to be rather "picky" when it comes to antennas, that is, if an antenna doesn't offer a good match, the Belka may have problems, now... this loop presents a very good match to the 50Ohm coax, so I think that the Belka may like it
A last consideration; imagine adding a preamp like this one
http://www.arrl.org/files/file/QEX_Next ... Steber.pdf
to the antenna, just add some relays to switch the "L1/L2" section and cover the whole HF and add a controlbox with a tuning potentiometer and a switch to select the band (through relays) and the result will be a remotely tuned, directional, preamplified antenna
.... but now maybe I'm pushing things too far
- well, any idea for a name ?
Crapbeam sounds not very attractive.