Search found 34 matches

by AD5NL
Wed Dec 14, 2016 4:55 pm
Forum: RTL-SDR Discussion
Topic: Directional antenna for GSM phone tracking?
Replies: 7
Views: 8790

Re: Directional antenna for GSM phone tracking?

A few random thoughts: 1. I know that RDF at VHF is usually done with small yagis. These do not have the greatest directionality (three element yagi has a main lobe that is something like 90 degrees wide). But that is sufficient to get a rough direction, particularly when multiple antennas are used....
by AD5NL
Fri Nov 11, 2016 10:04 pm
Forum: Antennas
Topic: Is wire length critical in QFH antenna?
Replies: 3
Views: 8639

Re: Is wire length critical in QFH antenna?

If you wanted to be a real purist, you could probably use a quarter-wavelength stub. Although to the best of my knowledge, nobody makes a 61 ohm coax. You could also try a 12th-wave transformer, which doesn't require funky-non-existent-characteristic-impedances. https://www.cv.nrao.edu/~demerson/twe...
by AD5NL
Fri Sep 16, 2016 7:08 pm
Forum: Antennas
Topic: Do magnets interfere with RF?
Replies: 3
Views: 9592

Re: Do magnets interfere with RF?

The only way I can think of that a magnet would create an EM field would be if they were moving. You know, like an electrical generator.
by AD5NL
Fri Sep 16, 2016 7:04 pm
Forum: User Projects
Topic: SDR CCTV Video Output
Replies: 5
Views: 22249

Re: SDR CCTV Video Output

Frequency depends on the setup. If it is wired, it is baseband. You might be able to get a weak signal in the HF range if you're real close to the wires though. If it is wireless, like last poster said, usually in a "junk" band like 2.4GHz. For baseband video, you can upconvert it (more or less) usi...