ANTENTOP- 01- 2017 # 021

Two Helical Antennas for 160 meter Band

Two Helical Antennas for 160 meter Band

Andre Chichkin, VE3YXO

First Design of the Helical Antenna

 Helical vertical antenna at its relatively small height may provide a good operation in the Air. It is possible to find the statement at lots ham publications in the internet and in paper magazines. So I decided to make my own helical antenna originally for 160 meter band and prove if the helical antenna works so well. Design of my helical antenna was based on source from internet and magazines that I had at my hand. What I have made in reality is shown in Figure 1.

Some words why the antenna looks so. Mast of the antenna was made from Fiberglass tubes in 103 cm length and 5 cm in outer diameter. It was surplus tubes from a military mask net. In Canada those tubes very often are sold in some auto (for example, Princess Auto) and hobby shop. EBAY as well has wide range of selection of the tubes- just type "Fiberglass Round Tube." The design of the tubes allows connect one tube to another one and that results easy create antenna mast in any length. At first I planned to use 12 such tubes to create my helical antenna. On the top of the mast I planned to install a fishing rod in 6 meter length. I planned wound 77 meters of the 14- AWG wire around of the mast. The Helical Antenna intended to be installed at my backyard.

So step-by-step I wound the wire along the fishing rod then along the first section from the Fiberglass tube then erect the design that was lean on to wall and then later on to roof of my house, then install the next section of the Fiberglass tube, wound the wire around the section, made next step, next, next and... Alas! The gigantic mast fall dawn because the base of Fiberglass tubes could not stand such mechanical force that caused upper tubes from the mast. My plan was corrected and the complete design of my Helical Antenna is shown in the Figure 1. The mast contained just 8 Fiberglass sections with broken fishing rod in 4 meter length. Overall length of the antenna was near 12 meters with near 60 meter wire wound around of the mast.

It was good looking high Helical Antenna but... it was a little problem. With help of my transceiver internal Antenna Tuner I may match the antenna on all amateurs HF bands but not on the 160 meter. I decided to add to the antenna a loading coil. The coil was wound on a water pipe that has diameter 5- cm and in 120 cm length. Coil contained 54 turns (it was near 15 meter) of 14-

AWG wire.

With this coil my Helical Antenna could match on all HF amateur bands and of course on the 160 meter. The coil was sitting on a plastic garbage can near base of the antenna. Figure 2 shows the coil near antenna base.

Figure 2

Loading Coil near Antenna Base

Feeding circuit of the antenna looks like a little complicated but it is logically clear. At first to the antenna was connected a 100 feet of 450- Ohm two wire line. The line was going from the antenna to my basement. Then the line was connected to Balun 9/1. It was allowed to me use a 15 feet of coaxial cable that was going from basement to my shack. RF- Choke was created near the Balun. It was the coaxial cable wound on a ferrite core- yoke from old TV. The choke may contain 10- 15 turns that is not a critical.

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