[CQ-Contest] World Records and Verticals
Marijan Miletic, S56A
s56a at bit.si
Tue Jan 4 07:43:30 EST 2005
Horizontal dipole needs 0,4 wavelength height in order to radiate at low
angles while verticals achieve that with 0,25 or even less!
Present aluminum technology puts a practical border for Yagi advantage above
5 MHz. Sea water helps 3 dB up to 0,25 wl antenna distance.
There is not enough reliable data on SO2R antenna separation subject. I
measured -17 dB attenuation between TH6DXX and 78 m Windom underneath on 28
MHz. So I built 30 dB antenna swap switch for WRTC-2000. Some operators
showed with microwave coax relays at WRTC-2002 in Finland. 5B4AGN measured
attenuation on Force 12 interleaved elements on 10/15/20 m and came down
to -12 dB figures. Easy to fry RX even with 100 W as some BPF have not
enough higher frequencies attenuation. Fortunately enough, very close RF
field decreases with third degree of distance measured in wavelength.
73 de Mario, S56A, N1YU
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