Many thanks to Stephen (G7VFY) who shares the following article posted on G4USI’s blog:
Xiegu ATU’s – just how good are they?
Preamble: Based on some social media comments, let me say at the outset that: a) I know that the ATU does not tune the antenna, but provides a good match to it; b) resonant antennas are more efficient; c) that you can tune a dummy load; d) just because you can tune something doesn’t make it an effective radiator. I do know these things. This post is intended as a bit of fun and to see just how much of a mis-match this ATU can handle to press objects into service as an antenna, even a very inefficient one. Please don’t take it too seriously!
Ask any Xiegu owner of the X5105, G90 or the XPA125B linear amp, and they will all tell you that they have great auto-tuners. Well, I own a X5105 and recently was lent a G90 for review for Practical Wireless. I decided to put the ATUs to the test using my X5105.
But what challenge to give it? Well, how about trying very, very long and very, very short antennas? What about metal gates, a cow shed roof, the framework of a polytunnel and a stock trailer?
Read on to find out how it really performs.
I love G4USI’s philosophy with this fun experiment: see if it’ll match, then see if you can get spotted!
Xiegu ATUs certainly have a wide matching range–so do the Elecraft KX series ATUs. Indeed, having a super capable trans match means that you don’t necessarily need an extra inline transformer to make matching a non-resonant wire easier.
And I see why G4USI mentions that there’s a difference between a good SWR and efficiency. It’s an important note because, yes, dummy loads will yield perfect SWRs!
Many, many moons ago, I used to participate in a fun contest where the idea was to make as many contacts as possible from not-so-standard antennas. The rules of the contest really pushed the operator to metal objects that, in no way, resembled an antenna. They didn’t allow electric fences or even gutters, if I recall correctly.
One year, I remember loading two identical small trampolines and my in-law’s house. I think I ran them QRP with my Elecraft K2 and used a ZM-2 manual tuner to match them. I’m sure they weren’t efficient, but it worked! I made several contacts with other contest stations and it was amazing fun!
Have you ever had success with a non-traditional antenna? Please comment!