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Old April 18th 05, 04:49 PM
Richard Harrison
 
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Ed wrote:
"I prefer "resonant" antennas fed with coax as opposed to open wire
feedline with tuners,---"

Bamdwidth of a resonant antenna depends on its antenna Q. A high-Q
antenna can cover a wide band by retuning for the frequency to be used.

Biconical antennas are used for their feedpoint impedance of about 72
ohms and for their low-Q (wide bandwidth).

A high-Q loop antenna can be efficient and smaqll but must be tuned for
the frequency of use. An interesting example appears in the July 1968
QST. It`s the cover story.

The loop is a rectangle 8 feet long and 4 feet wide made of
copper-plated aluminum rain downspout. It is tuned and loaded with
dual-section 500-pf variable capacitors such as pmight be used in a TRF
set. With additional switched-in fixed capacitors, it matches 50 ohms
from 2.8 MHz to 7.3 MHz, and from 14 to 22 MHz. It also works to 30MHz
with an SWR under 3:1.

This mobile antenna was mounted on a car roof. Some YL`s may not
appreciate its beauty.

Best regards, Richard Harrison, KB5WZI

 
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