There hasn’t been anything on the subject of antennas for a long time… but this is an ongoing topic here.
During a visit to Decathlon in France, I stumbled across the 6m telescopic mast.
I think many of you have it (in one or the other relabeled version)
Actually I didn’t need it at all… I’m well equipped. But 25 euros isn’t that much and since it’s already been there…
It’s been lying around with me for a while now and I really didn’t know what to do with it.
Somehow I recently became aware of an article about random wires and realized that about 6m is also one of those magical lengths. Of course, that goes very well with this mast. So why not? - Making antennas is fun.
Of course I have basic knowledge, but I don’t simulate anything on the PC … I don’t have a program for it either.
The antennas for SOTA - i.e. qrp applications - are mostly made of 0.14mm² / 26AWG copper wire.
Here is an antenna under 30 euros that has been tested in practice, but which requires a simple antenna tuner.
To bring a random wire (a length of wire that does not resonate on any amateur radio band) into a range that tunes well, a 1:9 Unun is commonly used.
I’m a fan of Unun and Balun in film cans …and so I used a film can again and this time installed a ground connection.
The toroid is an Amidon 82-43. I tried tormenting him with the KX2’s power output but he was cold. Over the entire range of 1 - 30MHz, the SWR remained close to 1.0X on a quickly built 420 ohm dummy. Everything weighs a total of 61 grams.
Because I didn’t want it lying in the dirt, I chose the wire length for the radiator at 5.80m. As always with my vertical, I make a holder out of shrink tubing to hold the wire at the top.
To create a counterbalance I cut radials (resonant in each band). The lengths don’t matter as a counterweight laid out on the ground, but there may be further experiments.
Together with the connection cable: 845 grams:
The first test was in my backyard… antenna on the 6m mast, radials laid out in a fan shape… and the values were as expected…
…and without the radials. The shielding of the 4m coax cable does more than I thought… But you could connect larger counterweight. Of course, the tuner of the KX2 has an easy job… but simpler tuners should also be able to achieve a good SWR.
Today I made myself comfortable on HB/SO-018 and set up my standard antenna and the new antenna next to each other. I was able to quickly make a comparison by reconnecting the BNC and retuning. Stephan @HB9EAJ was on HB/LU-004. We had a stable groundwave connection. He is also a keen antenna builder and thankfully took the time to make comparisons on different bands in ssb.
We had given each other the same reports. Of course, this is not an exact measurement… but it at least shows that the antenna is working.