[Elecraft] Urban stealth HF: Inside-the-backpack loop antenna?

[Grant Youngman]

The problem is loop diameter.  Efficiency on 20m of a 12” diameter loop would be on the order of 5%. Forget it entirely on 40m .. essentially a dummy load that would take around 1200 pf to resonate. On 17m efficiency would go up to around 11%. 

I use a loop portable all the time (Alexloop, W4OP) and they work well. They’re both about 3 ft in diameter. The Alexloop is light enough to be carried around hand held ... the W4OP needs a table top or tripod. 

Grant NQ5T

Sent from my iPhone

> On Jan 22, 2019, at 3:57 PM, Wayne Burdick <n6kr at elecraft.com> wrote:
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> 
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> So, just for grins, I’d like to try something completely incognerdo: no visible antenna. A small remotely tuned loop (say 12” diameter) would seem to be the best choice, as it would fit entirely inside a small backpack. It could have  modest efficiency while not requiring a counterpoise wire. Rigid 1” copper pipe formed in a square would be convenient to deploy. 
> 
> The loop would be only 6 to 8” from soft tissue, so you’d want to run QRP, of course.  OTOH, we’re talking about HF. A cellphone by your ear is probably worse. 
> 
> Any other antenna suggestions?
> 
> Wayne
>