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Loop antennas

R

Roger Dewhurst

Jan 1, 1970
0
Assuming that a single turn loop will receive a particular frequency better
than others will a multiple turn loop of the same diameter receive the same
frequency rather better?

R
 
C

Charles Schuler

Jan 1, 1970
0
Roger Dewhurst said:
Assuming that a single turn loop will receive a particular frequency
better
than others will a multiple turn loop of the same diameter receive the
same
frequency rather better?

The best performance will then be at a lower frequency (in general).
 
R

Roger Dewhurst

Jan 1, 1970
0
Charles Schuler said:
The best performance will then be at a lower frequency (in general).

How does the frequency change with increasing number of turns? Is there a
rule?

R
 
J

John Popelish

Jan 1, 1970
0
Roger said:
How does the frequency change with increasing number of turns? Is there a
rule?

Too many factors. At the very least, the resonant frequency must drop
inversely proportional to the total wire length in the loop. So
doubling the turns on the sane size loop must at least halve the
resonant frequency.

But this is a limit.

Assuming almost all the flux that passes through one turn also passes
through all the others, the inductance will rise almost proportional
to the square of the number of turns. The inter winding capacitance
and other stray capacitance also rises as the turns rise. These two
factors also lower the resonant frequency.
 
P

Phil Allison

Jan 1, 1970
0
"Roger Dewhurst"
Assuming that a single turn loop will receive a particular frequency
better
than others will a multiple turn loop of the same diameter receive the
same
frequency rather better?


** Multi turn loop antennas (or " frame antennas" ) are commonly used on AM
band receivers.

In this case, a loop of convenient size can be made to resonate within the
band of interest with a small fixed or variable capacitance in parallel.

Works well for local broadcast reception.



......... Phil
 
J

Jasen Betts

Jan 1, 1970
0
Assuming that a single turn loop will receive a particular frequency better
than others will a multiple turn loop of the same diameter receive the same
frequency rather better?

no. the multiturn loop will will receive the same frequency but with a
higher impedance (more voltage less current -> same power).

If you wany more signal strength, you need multiple loops, or other
strategically placed bits... look up "phase array" and "yagi antenna"
for two examples.

Bye.
Jasen
 
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