[TowerTalk] 80 M 4 SQUARE MODELING
gwj at wb9jps.com
Sat Jul 22 12:33:21 EDT 2017
One more thing that almost nobody pays attention to is the fact that the Comtek and DXE phasing boxes are optimized for one and only one specific array configuration: fat, full-sized verticals over a very substantial ground plane, and with no other interacting objects. They are NOT magic boxes that guarantee an ideal pattern under all circumstances; feedpoint impedance is key. Carefully study Low Band DXing. It is feasible to optimize pattern (especially F/B) for any reasonable set of verticals, but only if you do the detailed impedance measurements in the field, followed by the calculations, and finally some modifications to the phasing network. To verify everything, you can insert current transformers at the feedpoints and measure magnitude and phase, then tweak as necessary. I just went thru all this with a vertical array for 40m, and it was a real eye-opener.
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