In a previous post I wrote that building a half wave antenna for 20m is on my todo list. The reason for this that my groundplane needs counterpoises or radials. For the half wave or end fed this is not needed. That is what people usually say.
A few days ago I started building one. For the radiator I took 10 meter wire, 2.5 mm thick. That was the easiest part 🙂
To support the radiator I went searching for a fishing rod on the website of a known sport- and outdoor store. The Geopole series seems to meet my expectations with a length of 9,5 m (about 30 ft). I overlooked one thing in the description : it was made from carbon fiber. But I went to the store, the price was 50 euro. Just minutes before I got to the counter I noticed a small sticker. It was barely visible, but there it was : Carbon.
This goes back into the rack. Now what ?
I started searching again and the best alternative was a 7m pole. This time I looked for all kind of descriptions, texts, stickers, etc. I didn’t found the word Carbon written somewhere. And the price was just 16 euro. For that price they can’t build a carbon fishing rod. It is made of glass fibre.
Back home I started to wind the wire around the pole like a big helical. I used papertape to fix it temporarely. The fishing rod just fitted my garage.
The next step : The matching unit.
The impedance of a half wave is rather high, so you can’t feed it directly with your coax. You can use an LC coupler or an L tuner. I have choosen for the LC method. The radiator has a dc path to ground and is isolated from the coax.
After a while I changed the capacitor by a piece of coax cable and mounted the antenna in a more suitable place.
See my other more recent blog entry here
I finally bought a networkdrive to be used in my home network. My wife was complaining that all pictures were on the pc downstairs (my shackcomputer) and she want to see them also on the pc in the living room. Time to share the data. But I needed a NAS style disk, not just some usb drive.
I came acros the site of IK0VVE with a wonderfull description of a MEPT.
MEPT stands for Manned Experimental Propagation Transmitter and is usually very low power. He uses a crystal oscilator but I find them pretty expensive. So I Looked around the net for programmable oscillators. Those are even more expensive and in the most cases you need a microcontroller to programm them. The oscillators uses I²C for setting the frequency by setting the divider and table lookups, …..
my last entry was from february last year (exact one year ago) and then everything went quiet. What has happened since?
We sold our appartment and bought a house with a small garden. Early March we were alerted by friends that there was a house for sale in their street. We know about 5 families in that street, all our children attend the same school and and have approximately the same age. After a long weekend calculating and visiting bank sites to learn about loans we mailed our price to the real estate company. Monday morning we were phoned that our bid was accepted. Everything went fast from that moment on. We sold our appartment to my parents in law. In May we signed all papers and we are now the owners of a house. In June and July we moved.
For the hobby it was a bit giving and taking. I now have a separate shack, Measuring only 1,5 by 2,4 meter. I saw the appartment building as one big antenna mast, that is gone now 🙁 But I found the remains of a tv arial on the roof of our house. That should be a good anchorpoint to mount my X200 and a wire antenna for HF.
The garden is about 6 by 30m, just big enough to fit a FD4 antenna. The FD4 is almost ready, but the weather hasn’t cooperating lately.
Other projects I would like to to :
This article is a reprint from my original article published in 2004. I don’t use the antenna anymore (collecting dust in the basement) but the article will stay here for informational purposes.
I live in an appartment and don’t have the space to put up a large antenna for my Kenwood R1000 receiver.
I knew the excistance of magnetic loops, but I never spent time to take a look at it. Why ? Who knows.
For the main loop I used a soft copper tube, diameter is 10 mm, length about 3 meter.
Try to make a circle (not always easy). A friend of me, Carl ON7NH, has drilled and tapped M3 tread into it. This makes it possible to use solder lips. The entire loop is constructed on a sunday afternoon.
The smaller loop is about 60 cm in length (diameter 1/5 of the main loop), material is 1,5 square mm copperwire.
With the capacitor found in my junkbox, I can tune the loop from 2,9 Mhz till 10 Mhz. Other capacitors will give other tuning ranges, have to experiment here.