HB13DISH
Retired Mod
- Joined
- Aug 13, 2007
- Messages
- 3,764
- Reaction score
- 1
- Points
- 0
- Age
- 78
- My Location
- Middle East - Israel
I made this simple Yagi antenna about 20 years ago.
At that time I had open space from my balcony and I was able to breath fresh air and receive few VHF and UHF TV channels.
Now I am surrounded with high rise buildings, which attenuate TV signals.
Thanks to them I went into the satellite hobby.
Anyway, I found this antenna in my junk box and thought that it might be interesting to show it here.
At the time there was a broadcasting on channel 46 UHF from the north so I wanted to test that, as the usual IBA Channel 1 was broadcasting on ch 22 UHF and I needed a smaller size dipole.
The dipole was the tricky part, as a commercial UHF antenna uses aluminum tube and they just bend it gradually until it folds back to 180 degrees.
As I didn't know how to bend a tube (and still don't know), I thought of making it from an aluminum plate and cut it to the calculated shape using a hacksaw.
The template allowed for a self holding bracket with two holes, which was put into shape using a vise and a hammer until it was at 90 degrees.
The dipole has an impedance (I think 240 Ohms or 300 Ohms?) which is higher than the 75 Ohms that TV cable usually have, so I used a matching impedance PCB which came with a plastic holder, nuts and other accessories.
The three reflectors were made from the same plate, actually from the inside section first and only then started to work on the dipole.
The photos show:
1 - The antenna kit, without the holding tube rod.
2 - Fixing the dipole to the plastic holder, using the holding bracket with two holes.
3 - Adding the matching impedance inside the platic holder and screwing with the nuts.
4 - Assembly on to the rod tube, and fixing the three reflectors.
5 - Connecting the TV cable to the impedance matching PCB, and closing the PC holder with the cover plate.
I tested this antenna just now using a small portable TV set, and I can still get a good picture and sound, inspite of all the surrounding concrete.
At that time I had open space from my balcony and I was able to breath fresh air and receive few VHF and UHF TV channels.
Now I am surrounded with high rise buildings, which attenuate TV signals.
Thanks to them I went into the satellite hobby.
Anyway, I found this antenna in my junk box and thought that it might be interesting to show it here.
At the time there was a broadcasting on channel 46 UHF from the north so I wanted to test that, as the usual IBA Channel 1 was broadcasting on ch 22 UHF and I needed a smaller size dipole.
The dipole was the tricky part, as a commercial UHF antenna uses aluminum tube and they just bend it gradually until it folds back to 180 degrees.
As I didn't know how to bend a tube (and still don't know), I thought of making it from an aluminum plate and cut it to the calculated shape using a hacksaw.
The template allowed for a self holding bracket with two holes, which was put into shape using a vise and a hammer until it was at 90 degrees.
The dipole has an impedance (I think 240 Ohms or 300 Ohms?) which is higher than the 75 Ohms that TV cable usually have, so I used a matching impedance PCB which came with a plastic holder, nuts and other accessories.
The three reflectors were made from the same plate, actually from the inside section first and only then started to work on the dipole.
The photos show:
1 - The antenna kit, without the holding tube rod.
2 - Fixing the dipole to the plastic holder, using the holding bracket with two holes.
3 - Adding the matching impedance inside the platic holder and screwing with the nuts.
4 - Assembly on to the rod tube, and fixing the three reflectors.
5 - Connecting the TV cable to the impedance matching PCB, and closing the PC holder with the cover plate.
I tested this antenna just now using a small portable TV set, and I can still get a good picture and sound, inspite of all the surrounding concrete.
