Radios are irrefutably magic in that an unseen, unheard and untouchable to humans radio wave zips around and across the planet conveying music, voice and even web shopping pages. If that ain’t magic, I don’t know what is!!
An antenna’s role is to bridge the world of electronics within a cell phone or classic radio and the magical unseen world of radio waves.
Antennas come in all shapes and sizes reflecting the breadth of ideas around what is good, what works and what is practical. To me and rather simplistically three metrics define and drive an antennas design and implementation; efficiency, deployability and cost.
Efficiency is the ability or measure of an antenna to maximize the translation from the electrical world of current and volts to the unseen electromagnetic world of radio waves. An analogy is a light bulb. Its role is to provide illumination but sometimes it produces heat as a by product. The more heat and less light for a given amount of electric current/volts suggests an inefficiency ideally to be avoided. The same holds true for antennas where typically we prefer not to loose energy in the transition back and forth to the electro-magnetic world and this is governed by choice of material, use of coils/traps, height above ground and many many other factors.
Deployability is the ability or measure of how easy (and by correlation, time and money i.e. cost) it is to get your chosen antenna design built, setup and doing its job in the real world. Unfortunately, deployability and efficiency tend to work against each other. What can be small and easy to deploy for a given frequency range might be quite inefficient compared to a larger and possibly more complicated design.
My passion to operate a radio station from unique, possibility exotic locations dictates a temporary installation. Therefore, Transportability becomes a fourth and special criteria/metric for me. My antennas and everything else that makes up a portable radio station needs to fit in the hold of a plane and practically given excessive excess baggage costs into two checked items per team member. Starting from a team of one shapes the solution dramatically!
Ranking these for a DXPedition scenario places transportability first, then deployability with efficiency last.
However, attaining some minimum bar in each is essential as sacrificing efficiency for transportability defeats the joy and opportunity of operating from a remote location. If no one can hear you then clearly going was a bust.
Discovery and accomplishment are important to me. It’s fun to establish a goal and then research, plan and then iterate toward that goal. Whether the number of books written about antennas is the largest sub group in the amateur world is debatable but the number is huge. Finding truth within this emotive area can be illusive. Three tomes that I have found illustrative and inspirational are;
- Low Band DX-ing by John Devoldere ON4UN
- Array of Light by Tom Schiller N6BT
- ARRL Antenna Book by ARRL
I’ve always had a soft spot for vertical antennas since owning and using the Buddipole system. One of my most memorable contacts was from the San Francisco Maritime Museum’s pier (obviously over salt water) using a Buddipole. 3 watts, crystal clear two way communication to England using voice.
Verticals are a controversial topic.
Without doubt verticals over salt water (i.e a Caribbean Island beach or even San Francisco) have been shown to be a winner by Tom Schiller’s Team Vertical breaking world records in numerous contests during the early 2000s.
Many are quick to quip that verticals radiate equally poorly in all directions. Maybe so but sometimes hearing and communicating easily in all directions is advantageous in a contest. Array of Light has much detail about deployment location and using slopes to maximize gain and directivity.
Verticals are potentially easy to transport and deploy and finally are considered by many a more practical approach for the low bands such as 160m and 80m.
Last but not least verticals can exhibit the ability to receive and transmit those magical electromagnetic radio wave close to the horizon and hence facilitate super long distance communication (thousands of miles away) which given my penchant for being on a remote and exotic locale makes eminent sense.
Too many options, “cut bait or go fishing?”
Inspiration comes from those that have gone before and presumably know far more than me. Certainly that is the joy of reading Tom Schiller’s Array of Light. SpiderBeam as a company cropped up over and over again and with that and a certain amount of research including a chance to chat with Con (SpiderBeam’s founder) and Rick (antenna aficionado) at Friedrichshafen 2019.
They provide a rather useful cookbook to help get you (and me) started. With this I took the plunge and started building two verticals based on their 12m fiber glass collapsable pole. Efficiency especially for 40m suggested an all wires (i.e. no traps, no coils to drag down efficiency).
Bright colors help!
Picking ground matching brown radial wire and black guy cord was a really dumb idea. How many times did we trip over the radial and break them…more than once. Did we almost become the headless radio team…..more than once.
So with that I purchased SOTABeams highly bright and uplifting yellow radial wire and guy rope!!
The Compass Rose
In the comfort of your favorite armchair it seems trivial to lay out 4 (or more radials) at 90 degrees to each other. Apparently not so in the real world and brown wires don’t help. I need some system to improve laying them out as the efficiency/efficacy of a vertical antenna is dependent on the radials; the ground type they rest on, their length and their symmetry.
Modeling your antenna
No, not taking the antenna to the photo studio but more of a mathematical/statistical model of it.
Fortunately, free to inexpensive software programs are available that with a modicum of effort can help visual the performance (radiation pattern) of an antenna, the effect of design changes etc.
I’ve scratched the surface here but recognize the value and have sprung for EZNec+ v6 and another excellent ARRL publication, Antenna Modeling for Beginners (that’s me!!).
Beyond “yellowizing” the 40m, the 80m needs to be built now that I have acquired all the parts and I just (as of Oct 2019) completed most of a 6m-20m HexBeam installation that will be posted separately.
Building is good but the real acid test or reward is to get out and use this medley of antennas during a contest from somewhere fun; could be a Scottish Island, the Canary Islands, Azores or another of those charming Caribbean Islands.
Cycle 25, here we come!!