Aerial photography - Ancient Gallery

This is a combined BI and BIII array. The BI section is a conventional dipole and reflector. The BIII section has a slot dipole (note the position of the feed points), two reflectors, and two director chains. The advantages of having two director chains for Band III were clear; less clear was how to collect the signal. If two dipoles were used the outputs had to be combined with accurate matching and phasing. Many and various were the solutions, including delta matching, phasing bars, and the slot dipole.

Thanks to Pete for this shot.

I might add that when I was about fifteen I used to make large BIII aerials for DXing, using bits from scrap aerials. I used to make the phasing bars by fixing two pieces of wire between the terminals of the two aerials. I usually used coax for this, with the inners and outers commoned. I kept the two wires the right distance apart by means of spacers, and simply connected the downlead across the two wires at the mid-point. More by accident than design this must have been electrically efficient, because it worked really well.

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