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On Tue, 19 Jul 2011 20:28:54 -0700 (PDT), Jay Scherberth
wrote: Richard - Is there such a thing as a multi-band HF sleeve dipole or is this more of a VHF/UHF solution? Hi Jay, It is multiband if your tuner can pull the SWR into reasonable limits. However, you do NOT want the overall length of the antenna to exceed roughly a 1.25 wavelengths of the highest frequency you intend to multiband. This is for two reasons at that frequency: 1. Difficult to tune at 1 wavelength; 2. Radiation is directed up at a high angle if longer than 1.25 wl. Please read Sal's perceptive comments about hi voltage exposure; and observe his statement about choking the line. Futher, and this complicates the simple rules above, your sleeve dipole does not need to be made of equal length elements. This raises the prospects of another topic: Vertical, Off Center Fed Dipoles. As for building ground radials - skip that wasted effort. You have too little footprint available, and your ground isn't conductive enough to present that much loss. This is why I suggested the sleeve dipole. 73's Richard Clark, KB7QHC |
#2
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![]() "Richard Clark" wrote in message ... snip ... your sleeve dipole does not need to be made of equal length elements. This raises the prospects of another topic: Vertical, Off Center Fed Dipoles. Yes. Mine was mounted with the end of the bottom element within reach from the ground. I lengthened just the bottom element experimentally with a simple clip lead -- and that worked. Sometime "cheesy" works. :-) "Sal" |
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