Rudy Severns wrote:
Tom's correct, the issue is not "resonance" but rather what, if anything,
happens when you have a so-so conductor/insulator (a tree) in the
near-field and/or further out. Do the losses matter?
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Here are several data points on this subject.
Recording the relative readings on the dBµ and S/N displays of a Tecsun
PL-310 tuned to a 790 kHz directional station about 52 miles east of me,
radiating about 1 kW in my direction:
Location dBµ S/N
(dB)
(Tecsun 4-1/2 ft AGL)
Area clear for 50 ft around 32 15
Pin oak tree, 3' diameter trunk, 42 24
east side against trunk
Ditto, but west side of trunk 34 14
Gnd Wire of 50' utility pole 48 24
(Tecsun 9 ft AGL)
Gnd Wire of 50' utility pole 50 24
The field improvement when the rx is held against the east side of the trunk
is completely gone when the receiver is moved to the east about 15 feet. So
the effects are quite localized.
These locations were all within 100' of each other.
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Topband Reflector
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