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From: "Ashlock,William" <William.Ashlock@edwards.boc.com>
To: rsgb_lf_group@blacksheep.org
Subject: RE: LF: RE: Re: loops
Date: Mon, 11 Mar 2002 12:48:13 -0500
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Rick,

You are absolutely correct with your 3db increase for a doubling of the
area. I didn't account for the doubling of the Rac in the conductor. The
loss ground loss may increase in proportion to the width of the loop but
this factor is included in the measured Rac for the smaller loop and
therefore the loop size doubling would be close to a 3db gain. 

Bill A   

-----Original Message-----
From: Rik Strobbe [mailto:rik.strobbe@fys.kuleuven.ac.be]
Sent: Monday, March 11, 2002 4:35 AM
To: rsgb_lf_group@blacksheep.org
Subject: RE: LF: RE: Re: loops


Hello Bill,

>>So based on that a 10m high and 100m long loop should perform as well 32m
>>high square loop. Doubling the length of a long&low loop should increase
>>the radiation resistance by 4 and the loss resistance by 2, resulting in
an
>>overal gain of 2 (= 3dB). Does the above fit with your math ?
>
>I'm with you except that a gain of 2 would translate to a 6db increase. 

Quadrupling the radiation resistance will give a 6dB gain. But at the same
time the loss resistance is also doubled, what will inflict a 3dB loss. So
overall gain is 'only' 3dB.

Eg :
Assume you gave a loop with a radiation resistance of 1 milli-Ohm and a
loss of 5 Ohm. Putting 400 W into this loop will result in 8.94 A loop
current, the radiated power will be 80 mW (ignoring loop gain for
simplicity).
Doublong the loop length will increase the radiation resistance to 4
milli-Ohm and the loss resistance to 10 Ohm. With 400 W th loop current
will now be 6.32 A and the radiated power will be 160mW. This is a 3dB
increase.
The above assumes (simplifies) that the only losses will be 'copper loss'.

73, Rik  ON7YD


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