Yagi Multiple Element Comparison

By Kelvin Marsh, M0AID

November 2013

Back in October, following a discussion on the Active Elements reflector, I thought I would try an experiment gradually reducing the number of elements on my beam, and recording the results. I looked for the most distant station I could find, and it happened to be V6P in Micronesia on 20 metres.

The bearing was 22 degrees, and the distance was 8000 miles. Also, this was in the middle of the afternoon, and I would expect him to perhaps be stronger at other times.

The recording starts with the SteppIR antenna using 3 elements, and this is marked on the recording with 3 beeps. I then fully retract the Director, and the result has 2 beeps. Finally, I pull in the Reflector and this has one beep. I then repeat the sequence, but this time pull in the reflector first, followed by the Director. The final 3 beeps indicates a return to 3 elements.

I have to say, the difference is not huge between each retraction, but the difference between 1 and 3 elements is probably the difference between making a successful contact within a reasonable time, or spending significant time calling him without making yourself heard.

By the way, the signal strength on 3 elements was 7, and the signal strength on a single element was about 4. You can judge the readability for yourself!

The MP3 recording can be heard by clicking the following link:
V6P on 20 metres

The following day, I conducted a similar test with KH0M, but this time on 12 metres. The bearing was 30 degrees, and the distance 7500 miles. The entity is the Mariana Islands.

This time I worked him quite comfortably using 400 watts before making the recording. The difference between 1 and 3 elements is much more noticeable. Again, you will hear 3 beeps for the 3 elements, and so on. In the first few seconds you will also hear how I reduce the HF hiss by turning back the RF Gain, and during the two and single element recording you can distantly hear a Brazilian station calling on the frequency from behind me. Using the Director and Reflector dramatically reduces any signal from the back of the beam. Whilst KH0M was actually working split in the recording, attenuating unwanted signals from behind you can be extremely useful.

The MP3 recording can be heard by clicking the following link:

KH0M on 12 metres