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Old October 27th 03, 10:08 PM
Richard Harrison
 
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Reg Edwards wrote:
"You may just as well use the well-known arrays of 1/2-wave dipoles."

In most instances Reg is right and this is probably no exception.

There is an April 1986 artivcle in "CQ" magazine by Richard Fenwick,
K5RR on using two small rectangular loops, 85 in. on a side, and spaced
30 to 60 feet apart for 160-mtr. reception.

The loops are tuned to 1812 KHz using 620 pF capacitors. High voltage
capacitors are used for transmitting. K5RR says that "ten watts into the
loop will produce about 450 volts RMS across the capacitor."

This may be the place to use Reg Edward`s observation about the voltage
across reactances in a series resonant circuit; the ratio of reactive
voltage to applied voltage is equal to Q.

Page 2-27 of the 1987 ARRL Handbook agrees with Reg: "The voltage across
either the inductor or capacitor is QE, where E is the voltage applied
to the series circuit."

My ARRL L/C/F Calculator says 12 microhenries resonates with 620 pF, the
capacitance used to resonate the loops at 1812 KHz. The reactance is
only about 137 milliohms.

The author, K5RR writes: "The loops nave a very narrow impedance
bandwidth - only about 13 kHz for a 2:1 VSWR.

The author shows a unidirectional pattern for his two-loop array and it
was intended to replace a 400-ft. Beverage antenna in a distance of less
than 60 feet. A delay line of 180-degrees minus the physical degrees of
spacing beteen the loops is switched into the feed of one or the other
of the loops to reverse the sense of the array. Equal currents are fed
to the loops using a "Wilkinson power divider".

This two-loop array is an inefficient antenna meant only to compete with
a Beverage. It is fine for reception but better used with a more
efficient antenna for transmission.

Best regards, Richard Harrison, KB5WZI