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.