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RW3XA’s 9 Band HF Vertical Antenna

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ANTENTOP- 01- 2005, # 007

RW3XAs 9 Band HF Vertical Antenna


Generally speaking, the purchase of those aluminum tubing derives from the time of availability to purchase this tubing set for that moment (it was in 1996). Total length turned out to be nearly 13 meters. It was measured by footsteps :-), in case of checking my idea it was not necessary to measure it more precisely! Only in a couple of years, when I was replacing nylon guy ropes and with the request of my friends, I measured exact length of the aerial, it turned to be 12.85 meters long exactly. In fact, the exact length is not critical - matching network can compensate it. However, it is necessary to bear in mind, that even small changes in aerial dimensions (see below) can affect matching network adjustment and even its circuitry changes, as a result match work can take more efforts.

This article is written to share real results and to simplify tuning, to minimize painful creative researches while constructing the antenna.

The Design.
  5 meters of the lowermost tubing (see fig.1) - 50mm diameter, further 5 meters 40mm diameter, 2m- 20mm diameter, and 85cm 10mm diameter tubing. All aluminum tubing, total length 12.85m. 2.85m from the top end of the mast, between 40mm and 20mm tubing, 4 folded capacitive loading 3mm copper wires 1.4 meters long are connected to the mast. Free ends of the wires terminated by insulators to which nylon guy ropes fasten the mast to the ground plane. The basic unit construction of the mast along with ceramic insulator is clear from the fig.2. It stands on a steel 10mm ball, it helps much to withstand wind loads.



Fig.1. The overall dimensions of the aerial.

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February 11, 2018 23:18

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