Every shack should have at least one. This type of tuner has been around for a while. While the Z-match can take on several variations, what distinguishes it from other circuits is that it is a resonant circuit that uses a fixed inductor. Some Pros and Cons Why the popularity? Here are some advantages that the Z-match design offers: Matches balanced loads without the use of lossy baluns. Being a parallel resonant circuit, the Z-match can provide some band-pass filtering for your receiver and harmonic attenuation for your transmitter.
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Years back, I did a write-up on a simple, random wire antenna made from a foot roll of speaker wire from a local dollar store. I had a similar roll of wire in my junk box, so I set out to see if I could build another useful portable antenna from it. This time out, I wanted to build something more elaborate than a random wire.
After some sketching with a pencil and paper, I came up with this simple portable delta loop. There are certainly better ways to construct a delta loop. However, I just wanted to see if I could build a functional antenna using only cheap speaker wire.
For the next band below the fundamental, he suggests connecting the feeder wires together and using it like a random wire. Given that I constrained myself to a foot roll of speak wire, I scaled my antenna for the 20M band. Using the formula, divided by the frequency in megahertz, I calculated a total length of 71 feet That would leave some of the two-conductor wire for an improvised balanced feeder.
Feeding the delta loop in a corner with the apex of the loop pointing up , gives the antenna vertical polarity with a low take-off angle. However, this antenna is still quite useful at practical heights in the field. Since a tuner will always be necessary, I expended no effort trying to optimize the design. Measure off Place a small zip-tie around the wire at this point. Separate the Strip and solder the loose ends of the Put some electrical tape or shrink tubing over the splice.
Make 3 small loops in the wire, as shown in the diagram. You can see an example in the accompanying photo. These are going to be the attachment points. Finally, install some spade terminals on the ends of the shorter conductors. These will be used to attach the antenna to your tuner or balun. Example attachment point. This is the feedpoint of the antenna. The two wires to the right are part of the loop antenna, while the wires towards the bottom serve as the balanced feedline.
Deployment For my initial tests , I used a foot Jackite pole to support the antenna. I only partially-extended the pole, such that the bottom of the antenna was about 4 to 5 feet off the ground.
I used some nylon twine and a couple of tent stakes to tie off the two bottom corners. This is the delta loop set up for my intial testing. The light-colored wires were difficult to photograph, so I enhanced them for visibility.
The setup was somewhat more complicated than most portable antennas I use. I used a couple of large tent stakes to keep the feedline off the ground. I connected the antenna to my KX3 using a balun and a 1-foot piece of coax. I used a couple of large tent stakes to keep the balanced feedline portion of the antenna off the ground. I did have a usuable match between 7.
I was only about 50 yards away from some powerlines, but the loop seemed quiet on receive. I also made contacts with Missouri and wrapped up with yet another French station. From the signal report the last station gave me, this antenna appears to do reasonably well with DX on 20M running QRP. Wrap-Up Although my initial outing with this antenna was promising, I need to spend some more time using it on bands other than 20M.
In any event, it was a fun—and cheap—antenna project. QST, 24— Share this:.
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9780872593657 - W1fb's Qrp Notebook by Demaw, Doug