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0 pointsgiantrobot5y ago0 comments

Note also with a highly directional high gain receiver that tiny bit of radiating energy is very detectable. It's just going to feed into background noise for most receivers so no one cares. But it will be detectable by a motivated hunter with the right equipment.

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pps435y ago

A directional antenna has to be much larger than wavelength. Won't fit in a van if we're talking about HF (with wavelengths measured in tens of meters).

giantrobotOP5y ago

Not[0] really[1]. Loop antennas (active or passive) have good gain perpendicular to the loop. It would be easy to mount on the inside of a wood paneled moving van with some nice receiving equipment. You park the van so the side faces the target's apartment and voilà you can listen to the mixer of their superhet radio. If your searching for receivers a couple vans driving around could triangulate and detected signals. Just getting the right apartment building would be enough for the KGB to turn the place over.

[0] http://www.kr1st.com/swlloop.htm

[1] https://www.fmuser.org/fm-receiver/receiver-antenna/DE31MS-l...

pps435y ago

You can make a small (relative to wavelength) loop antenna that has a sharp minimum, but it will be very inefficient. You want your directional antenna to have a sharp maximum (high gain) so that it can increase signal to noise ratio.

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pps435y ago

A directional antenna has to be much larger than wavelength. Won't fit in a van if we're talking about HF (with wavelengths measured in tens of meters).

giantrobotOP5y ago

[0] http://www.kr1st.com/swlloop.htm

[1] https://www.fmuser.org/fm-receiver/receiver-antenna/DE31MS-l...

pps435y ago

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