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Loop antenna question.
G'day all, one for the full wave loop antenna boffins out there. Is it ok to have a metal mast running 'through' a full wave wire loop antenna?
I've been doing this for years with quite good results (a diamond shaped wire loop hung off a metal mast with the sides tied off as required), yet I wonder if it is really acceptable and/or detrimental to loop antenna performance to have a metal object running the whole way through the centre of a loop Any thoughts? Regards, Felix (vk4fuq) aka catman. |
#2
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I used PVC pipe to construct my MW AM loop. Nearby metal can influence the pattern. I am mainly concerned about being able to produce sharp nulls to reduce signals from interfering stations on the same frequency, so wish to keep the pattern "clean".
I know that MW broadcasters in this country must pay special attention to nearby metal towers (such a cell phone and TV towers) even to the extent of installing tuned "skirts" on said towers to reduce their effects on the MW station transmit pattern. jr |
#3
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I used PVC for my 2 meter loop antenna. It worked well.
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#4
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Quote:
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#5
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Yes and Yes!
But I was not fond of the remote tuning... IIRC, it introduced a small amount of "hum" on some stations, so I changed to manual tune, (variable cap in the black box) and use a portable radio held near the loop to tune it. jr |
Audiokarma |
#6
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Quote:
Antenna Pix: DIY and Store Bought -- Post 1 Antenna Pix: DIY and Store Bought -- Post 5 For the remote tuning did you use some geared down motor (stepper, etc)? Right now my loop's in the house but I would like to have a smaller weather-proof one mounted in the back yard on top of a 16-foot pressure treated post and as far away from background noise as I can get it. |
#7
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http://www.randombio.com/loopantenna.html With 1Meg resistors, I picked up "hum" on some stations, likely due to nearby power lines in my area. If I lowered the resistance enough to eliminate the "hum", the tuning of the antenna became very broad (low Q)... so I installed the manual tune box, seen above the rotor. jr |
#8
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Quote:
Even though I don't have a remote loop I'll still on occasion use a portable (RF-2200, ATS-803A) to peak the loop because the receiver / tuner lacks a signal strength meter and the AGC masks audible peaks. When I first got into this stuff I thought everything had to be up on the roof or in the attic or on some high mast. But that's not the case with AM. Anyhow good work. |
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