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Old 14th Feb 2018, 1:10 pm   #32
G8HQP Dave
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Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
Default Re: My first frame aerial

Quote:
Originally Posted by Boom View Post
Be that as it may the loop is giving me clear reception of stations that I want and rejecting all the noise, hash and adjacent channel interference that a 60 feet long wire gives.
The loop rejects local noise/hash because it is less sensitive to longitudinal electric fields than it is to transverse electromagnetic fields. A "long wire" is more sensitive to longitudinal electric fields than it is to transverse electromagnetic fields. This gives the loop an advantage on reception, but not transmission. The loop has narrower bandwidth than a "long wire" and so can reject adjacent channel interference, at the cost of having to retune. This is no advantage for transmission, unless the transmitter is faulty.
Quote:
Of course if I put filters in the long wire to supress the hash (can it be done?) and bandwidth controls on the receiver to try and stop the adjacent channel intereference and found some way to make the 60 foot long wire go in the direction of my choice I might achieve the same thing as the loop seems to be doing.
You cannot filter away hash if it is at the same frequency as the wanted signal.

I am not knocking loops. They can be very useful for reception under poor conditions. I am just pointing out that their advantages for reception are not because they are good at receiving wanted signals, but because they are quite bad at receiving unwanted signals (local noise, off-channel, other directions). This means that their usefulness for reception does not translate into usefulness for transmission.
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