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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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