Going Magnetic Loop

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Steve - K4HX:
This guy has already done it.

http://amfone.net/Amforum/index.php?topic=12451.msg91347#msg91347

ke7trp:
This guy gets on 75 with us.

http://www.qrz.com/db/K8NDS

His Signal was right there with the rest of the Dipoles on the band. 


C

W0BTU:
Quote from: ke7trp on October 19, 2011, 12:04:54 AM

This guy gets on 75 with us. http://www.qrz.com/db/K8NDS

I've worked Rich on 40 SSB, and he's loud. But if he runs the legal limit on AM with that loop, that's impressive. If there were a lot of losses, it would smoke.

Keep in mind that loop is only five feet off the ground! :-)

Opcom:
How are magnetic loops at rejecting line noise?

W0BTU:
Quote from: Opcom on October 19, 2011, 01:17:57 AM

How are magnetic loops at rejecting line noise?

They were almost meant for that purpose. The rejection of a single, local RFI source at very low angles is excellent. You would probably want to use a rotor.

The null is much less pronounced at higher angles, but can be >50 dB at 1 or 2 degrees elevation. You can see that in the EZNEC 3-D model below. Notice the deep null along the X axis at ~5 degrees which decreases rapidly as you go up. (This model is a 6' diameter loop 5' high on 40 meters.)

I will probably not rotate mine (at least initially) since I have Beverages and very little line noise. But the null is quite sharp, and if you need to null line noise, etc. then a rotor is almost a necessity.

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