Search found 175 matches

by Andrew (grayhat)
Wed Oct 16, 2024 3:57 pm
Forum: Field Kits and Reports
Topic: Fara-J fabric J-pole for 2m/70cm
Replies: 5
Views: 9517

Re: Fara-J fabric J-pole for 2m/70cm

I don't think that design would work with the materials I used for the fara-J - the nylon webbing is only 1 1/4 inch wide. Maybe you could run two strips of nylon from a couple of spreaders though. The faraday tape is pretty cool. I think the nylon webbing could be bought with the size one wants, t...
by Andrew (grayhat)
Wed Oct 16, 2024 7:56 am
Forum: Questions & Advice
Topic: Will this compromised antenna work?
Replies: 15
Views: 6608

Re: Will this compromised antenna work?

Brian, if you're in the mood of experimenting a bit, here's an idea for you; we know that the AX-1 covers the 20, 17 and 15 meters bands, now... what about adding it 30/40 meters (or even more bands) coverage :D ? Here's the idea We start by building or buying a 9:1 (just an idea, other ratios may b...
by Andrew (grayhat)
Tue Oct 15, 2024 4:10 pm
Forum: Questions & Advice
Topic: Will this compromised antenna work?
Replies: 15
Views: 6608

Re: Will this compromised antenna work?

Location is also important. I have a homebrew DS1-type antenna (6 foot whip and a coil at the base). I can make contacts here in the lower 48, but I couldn't even hear anything on it from Denali Park last month. Mike, try this; open this mapping site https://caltopo.com/map.html center the map on y...
by Andrew (grayhat)
Tue Oct 15, 2024 3:58 pm
Forum: Field Kits and Reports
Topic: Fara-J fabric J-pole for 2m/70cm
Replies: 5
Views: 9517

Re: Fara-J fabric J-pole for 2m/70cm

Just in case, the images below shows the "oblong loop" recalculated for the 2m band, sizes are in metric units, the model is for an antenna built using teflon insulated copper wire with 1.5mm diameter, and they should be used as a coarse indication, recalculating them won't be a problem, I...
by Andrew (grayhat)
Tue Oct 15, 2024 2:23 pm
Forum: Questions & Advice
Topic: Will this compromised antenna work?
Replies: 15
Views: 6608

Re: Will this compromised antenna work?

Ok, added the car, the wireframe model is really raw, but it should give you a better idea and... yes, the car has an influence on the pattern, just look at the attached pic which shows the radiation pattern on the 20m band

download/file.php?id=179
brian02.jpg
brian02.jpg (72.11 KiB) Viewed 3346 times
HTH !
by Andrew (grayhat)
Tue Oct 15, 2024 12:49 pm
Forum: Questions & Advice
Topic: Will this compromised antenna work?
Replies: 15
Views: 6608

Re: Will this compromised antenna work?

<GRRR> :( :( :( I stand corrected, when putting together the model, I forgot a dot, so I was testing a frequency of 14000 instead of 14.000 MHz, go figure :( Ok, this time I got it right, aside from the lack of "the car" (but I'm planning to add it !) here's what the antenna looks like whe...
by Andrew (grayhat)
Tue Oct 15, 2024 10:47 am
Forum: Field Kits and Reports
Topic: Fara-J fabric J-pole for 2m/70cm
Replies: 5
Views: 9517

Re: Fara-J fabric J-pole for 2m/70cm

Now that's interesting; willing to improve gain you may consider using the same approach to build a so-called "oblong loop", basically you have a rectangle with the short sides at top and bottom, the sum of the short sides length will be 1/3 Lambda and the remainder 2/3 will represent the ...
by Andrew (grayhat)
Tue Oct 15, 2024 10:38 am
Forum: Questions & Advice
Topic: Will this compromised antenna work?
Replies: 15
Views: 6608

Re: Will this compromised antenna work?

Brian I've put together a "quick and dirty" model in 4NEC2, didn't include the car (which will have effects) but at a quick test, the antenna shows a multi-lobe radiation pattern with low takeoff angles and a preferred direction toward the shorter (VHF/UHF) whip, will try playing a bit mor...
by Andrew (grayhat)
Sun Oct 13, 2024 6:34 pm
Forum: General Discussion
Topic: EFRW and VNA
Replies: 9
Views: 5806

Re: EFRW and VNA

not totally sure, since I'll need to run more verifications, but I believe that it may be worth trying a 16:1 in place of the 9:1, the resulting SWR curve may possibly become more "flat"
by Andrew (grayhat)
Sun Oct 13, 2024 7:15 am
Forum: Questions & Advice
Topic: Will this compromised antenna work?
Replies: 15
Views: 6608

Re: Will this compromised antenna work?

Thank you, on monday will put together a NEC model, I'm curious about the pattern