----- Original Message -----
From: "John Andrews" <[email protected]>
To: <[email protected]>
Sent: Wednesday, December 18, 2002 9:18 PM
Subject: LF: Re: Re: jason etc
> and a similar antenna at the receiving end instead of small loops or 3
feet active type antennas.
Just curious -- since the signal to noise ratio in my receiving
installation
appears to be limited by external (man-made and atmospheric) noise, rather
than noise in my preamp/receiver, how would a 100 foot tower improve that
situation?
In my case the 120 ft vertical top loaded system, comprising 4 inv L
structures resonated on 136 khz is a good 12 db better at receiving signals
than my 90 metre perimiter loop resonated also on 136 khz and top wire
height 70 ft. I am comparing signals from the loop in its optimum direction.
E/W. Both systems are configured for 50 ohms match to the RX.
I live out in the countryside and noise is not a problem. Some are getting
confused and discussing the merits of a vertical against a loop in noisy or
Urban environments. I am discussing the two antennas in a noise friendly
area, and as someone has pointed out loops also pick up quite a lot of noise
depending on your location.
The only loop worth while is a full wave loop at the frequency of operation,
the smaller you get in relation to natural resonance the less the capture
ability and more critical the tuning, and going off resonance with the
slightest movement by wind, rain etc, so it is seldom optimum at the
required frequency except you happen to live in Dixie or Texas where the sun
always shines!!
73 de Mal/G3KEV
John Andrews, W1TAG
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