Re: [Discuss-gnuradio] Cheap portable antenna for SSB + CW w/ USRP1?

[Mark Cetilia]

Hi Louis,

Thanks for the leads—the mini-loop tuner looks like a great possibility,

though it seems like I'd need to swap out for a different size loop 

each time I want to change bands—1/4 wavelength, they say—

but is there maybe some flex room in there?

Also confused as to whether it would help to have 

an active loop for receiving, or if that's just for sending?

Apart from having built a square loop antenna 

for receiving VLFs (from the Calvin R. Graf book), 

I'm a total newbie when it comes to antennas, 

so it all seems a bit daunting, as I'm sure you can imagine :)

Cheers,

Mark

--
mark.cetilia.org | mem1.com | reduxproject.com

On Oct 7, 2011, at 10:20 PM, Louis Brown wrote:

On Oct 7, 2011, at 11:01 AM, address@hidden wrote:

[Discuss-gnuradio] Cheap portable antenna for SSB + CW w/
USRP1?

Since you are only interested in RX, a loop would probably work well.  You could probably rig up compact, muti-turn wire loop that could be broken down and folded.  A simple passive loop requires a high-Q, variable plate capacitor you must tune for resonance, so it is inherently narrow band, but that also gives you rejection.  They are lossy too, but HF is dominated by atmospheric noise so noise figure is not a prime concern.  MFJ-952 is a mini-loop tuner; just add your own wire.  There are active loops too. This is a list:

http://homepages.tig.com.au/~vk5vka/antnews.htm

Active loop design:

http://sivantoledotech.wordpress.com/2010/09/18/a-tuned-active-receiving-loop/

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