Ham radio antennas

Sometimes stories just start in the middle, and that is where we are right now, in the middle of some activity regarding my amateur radio station (ham radio). I have had my license since 1973 and this hobby has helped me to do many things such as: make friends around the world; learn about radio-electronics; understand something about solar physics; and learn how to build electronics circuits from scratch. This past weekend I needed to adjust some antennas before the temperature drops to well below freezing and the snow begins to pile up.

The antenna is an important part of the station, it is what collects the signal and brings it to the radio. It is also what allows the radio to emit a signal out for others to hear. Antennas can be built to serve different purposes such as to be very good at just receiving, good at transmitting in all directions, or good at sending the signal in one particular direction. I like building my own antennas out of wire to suit my needs within the limits of trees, power lines, and rope.

Radio emissions are waves, specifically electromagnetic waves with particular frequencies and wavelengths. Following tradition, the frequencies allocated to amateurs commonly are referred to by their wavelengths rather than by their frequencies. In the high frequency region I operate at amateur wavelengths of 80, 40, 20, 15, and 10 meters, long-time ham bands. In the more recent past we have gained allocations at 60, 30, 17, and 12 meters. I also operate on the very high frequency wavelength of 2 meters. There are other wavelengths available for amateur use, many of which I am not set up to use right now.

In general, the antennas are most efficient when they are resonant, that is, when they are a certain whole-number fraction of the operating wavelength. For example, we can refer to antennas as being a full, half, or quarter wavelength long. Non-resonant antennas also work, but a matching device is needed to ensure that the maximum amount of energy is transferred between radio and antenna and is not converted to heat or other losses. I can use the same antenna for resonant and non-resonant wavelengths through the help of an antenna matching device, also called a tuner. Bear in mind that making an antenna work and making it work efficiently aren’t necessarily the same thing.

Here I am adjusting the tension on my W8JK two-element array. This antenna is shaped like the letter H in the horizontal plane. In the picture below you can see one end attached to a chimney and the phasing line that runs between the two dipole elements. The antenna is designed for 30 meters and has two half-wave dipoles fed out of phase and about one-quarter wavelength apart. It focuses the radiation in two opposite directions. I have it aimed towards central Europe to the northeast and the west coast to the south west. I have had great success on this antenna working other hams in Europe running my now usual output power of 1 watt. This antenna has been pressed into service on 20, 17, and 15 meters with similar results.

Above my head is the feed point for my 80 meter long loop antenna. Until last year I had it set up as a long wire, but a large limb took out the far end support. I then made a new support but the antenna had a bend instead of being straight and the modified run was too close to power lines for my liking. I finally figured out a path for a loop. Not an easy task as the antenna is made from copper plated number 10 wire that it is unwilling to be strung between and around trees. The antenna is very quiet, by that I mean it doesn’t make as much background noise (static) as other antennas do. I use my tuner to adjust this antenna to work on all the high frequency wavelengths. So far, it has been a great antenna. It seems to work well is most directions.

 

Attached to the chimney that is just barely visible in the first picture is my vertical antenna for 2 meters. This antenna has two loops that look like trombone slides. These are phasing lines. This antenna is actually three half-wave sections fed in phase and the phasing lines perform this geometric adjustment function. It works great on 2 meter FM to get my signal into repeaters on the other sides of our surrounding mountains. The wires are secured to a bamboo pole borrowed from Mary’s garden, and so far it has weathered three winters without much damage. The other antenna on the tripod is our microwave link for the internet (and it is a strong source of unwanted radio noise…a complaint that I will skip over for now).

Now that these antennas are all set for the winter I can spend more time inside on the ham radio with my hot cup of tea.   73 de KQ1P.

Comments

  1. Polly says:

    Interesting stuff – if you point the antenna away from Europe and in some other direction would you have better luck getting other geographies? Hope the cleaning out of the ham shack is going well.

    • John says:

      Yes, the aiming is important but there are many hams in Europe and the trees are oriented just right. Shack is cleaner, one large box of trash and one box of give-aways… but not done yet!

  2. You actually make it appear really easy along with your presentation
    however I find this matter to be really something which I feel I would never understand.

    It seems too complex and extremely large for me.
    I am looking ahead on your subsequent put up, I will try to get
    the grasp of it!

    • john says:

      Many things seem hard at first. The cost of materials is low and cheap materials can be found with a small effort. My first antenna was made from salvaged telephone cable and the current version on my W8JK beam was made with TV style 300-ohm twinlead that I bought at a salvage store. The hardest part was finding high points to tie off the four corners.

  3. Evan says:

    Hey OM, saw your piece on your antennas. FB. That is neat that you have the room to string up several antennas.

    I live on a small city lot and am fortunate enough to have a couple of good antenna trees. I have a random length vertical loop and 100-ft. dipole, both fed with 450-ohm ladder line. The majority of time I use the loop. For years, I used a GAP antenna, the Titan DX. The day I put up the wire antennas is the day I stopped using the vertical. There is nothing like a whole lot of wire up in the air to radiate your signal. And while beams are nice, I think wire antennas make it more challenging.

    73, Evan AA8TK

    • john says:

      Evan- Thanks for your comment, I have always used wire antennas even when I didn’t have much outdoor space. I am now working on an antenna using a broken camp cot with an aluminum frame (2 meter beam maybe) and a Moxon beam that I steer using clotheslines. Still in the design phase but hope to have these up this summer.
      73
      John

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