Foundations of Amateur Radio


Starting in the wonderful hobby of Amateur or HAM Radio can be daunting and challenging but can be very rewarding. Every week I look at a different aspect of the hobby, how you might fit in and get the very best from the 1000 hobbies that Amateur Radio represents. Note that this podcast started in 2011 as "What use is an F-call?".


Foundations of Amateur Radio navigateright Episode

Delta Loop for Portable Operation

Foundations of Amateur Radio

Today I learned something new. A good antenna makes a big difference and you can hear it.

Of late, I've been using the antennas on the boot of my car and have for some time all but abandoned my 12m spider-beam squid pole. As you might recall, the very first antenna I ever built was a quasi-random length vertical with 16 radials. Each of the 17 wires is about 12.5 meters long, so there is a lot of wire, wound onto a garden hose reel for transport, lots of effort in setting up, lining up and stuff to do before I can actually get on air. In a HF quiet area it works pretty well but it's too big for most back yards; it takes up a circle of 25m diameter and needs either guy wires or a car at the base.

I went back to the drawing board. Using my trusty SG237 antenna coupler, I found a design online for a delta-loop. It's 120 foot or just over 36.5 meters of wire, setup in a triangle with the SGC coupler at the middle of the base. Yes, I know, the take-off angle isn't optimal, but oh my, what a difference in signal strength. Of course, from a setting up perspective, strap the squid pole to a vertical structure of some sort, roll out the wire, stick it to the top of the pole, erect the pole, click the antenna coupler in place and you're good to go. Call it 5 minutes.

Perhaps an analogy that will help is that the difference between the HF antenna in my car and the delta-loop suspended from the 12m pole is like cleaning your glasses, you can see perfectly well through them, but when you clean them, you can see more than you thought was there.

For my portable contest and QRP operation I'm going to have a look-see at a set of delta-loops, still suspended from my squid-pole, but this time cut to resonant length with no tuner at the base at all - and I can feed it at the bottom corner where it makes for a better take-off angle.

Before I forget, a take-off angle is like the angle at which you skip a stone across a lake. If you do it too steep, you get bloop, rather than a skipping stone; the better the angle, the more skips. The same is true for HF radio signals. Make the angle too high and you get bloop, make it low and you can hear stuff on the other side of the planet.

The experimentation with antennas continues, and I'm beginning to learn, it will for the rest of my life.

I'm Onno VK6FLAB