Tuesday, February 20, 2018

The W3DZZ Inverted L Antenna with Top Band

Back in 2011 when I built the W3DZZ trap antenna for 40 and 30 meters Len Paget GM0ONX who originally came up this particular way the W3DZZ is designed also came up with an inverted L antenna based on another W3DZZ design, I described it earlier in my blog (see the "my Blog" link below).
Here's the general view of the antenna
The antenna had been lying dormant in my shack as I was using the original 80/40 meter W3DZZ and so had no use for it. But as the time has passed, last week I felt like a change so I dismantled the original W3DZZ for a serious service which it desperately needed and have replaced with this Inverted L W3DZZ.
The difference is that besides the 80 and 40 meter coverage I can get Top Band, which is quite fun as it’s still a fairly new band to me and I thought it’s about time I really started to get in to it, plus I could try my hand at doing some DX!
Basically Its just adding some more  wire to the end of the original inverted 80/40 L antenna, 8.54m to be exact! The length does vary slightly from location to location because not only is there a shortening effect caused by the inductance in the 3.5 trap, there will also be a significant capacitance effect on 1.8 MHz as the antenna is close to the ground. All the details regarding build can be found either on Len’s page GM0ONX or on my blog

The traps needed some checking and adjusting from sitting in the shack doing nothing and now I'm happy with the 80 meter trap it's 1.5 SWR at 3.600, but the 40 meter trap needs more work to get the SWR in the sweet spot, it's a little high at the moment. Once both traps are ok I can concentrate on the actual wire, it's 14 gauge and I need to make sure all the measurements are correct. The actual tuning is fairly easy but Len does state the 7Mhz will probably need rechecking and adjusting and on a quick test I've already seen its the 7MHz portion causing an issue.

The 40m Trap

The 80m Trap
The other bit I should mention is when first built the antenna I used a ground rod for the earth connection, but quickly found on testing that a series of ground radials were needed. Where it’s positioned at the back of my house I am limited in what radials I can put out, but I hope in the next few days to get at least 10 or 12 ½ wave lengths out.
The ground rod is very limited at the moment
First impressions are it's a pretty good antenna but obviously for its size it's never going to be the best Top Bander, the other limitation seems to be the width on Top Band, it's quite narrow, but with the help of an ATU it seems to be working OK and I will try to improve as I go along.


  1. Great post! I really enjoy experimenting with antennas.

    I recently started a blog about operating QRP outdoors and I invite you to check it out. I hope you don't mind me adding a link back to your blog on my blog list.

    72 de Mike KQ9RP

    1. Hi Mike,
      Glad you enjoyed the post, you cant beat experimenting with the wires! This is a great antenna for the 3 lower bands. I will add your blog to the readers list.

      73s Richard M0AUW