I’ve worked Peter, VE3SO many times. His antenna is an MFJ1788 magnetic loop antenna mounted inside his garage. He recently sent me this writeup, and I found it interesting, so I asked him if I could post it here. In general, I’m not really fond of magnetic loop antennas, but Peter has made his work. If a magnetic loop antenna is all the antenna that you can have in your particular situation, then that’s what you gotta go with…..Dan
The loop is in the garage. It is a single car garage that is attached to the house. The garage is insulated and dry walled. Ceiling height is 12 feet. The antenna is mounted on a wooden beam to get it in the clear as much as possible.
Normally I operate with the car inside & the metal garage door down. To prevent anyone from seeing it when I have the garage door open, I put a white poster board in front of the antenna. It has no effect on the antenna’s performance.
When I first got the loop I tried it out hanging from the ceiling in the basement which for the 3 out of 4 sides is below grade, & to my utter amazement it actually worked. I have seen reports on magloop group on yahoo that others have built magloops & have had them hanging in their basements & they actually worked pretty well too.
You will notice that I painted the plastic cover of the magloop white instead of its usual black. Originally I was thinking of installing it outside & wanted it to blend in with a white fence that we have. After using it in the garage for more than 6 months, I have decided it works well enough there & I am going to leave it there.
There are others that make good magloops but the MFJ was readily available in Canada, so I went with it. Some really nice ones are made in Europe but shipping costs can be really discouraging.
The rotor on the loop does not change the polarization. It simply allows me to rotate the loop around the vertical axis. This allows me to ensure that I am not trying to have a QSO
with somebody that is in the nulls of the antenna. These nulls are approx. plus/minus 7.5 degrees, and are located perpendicular to the plane of the loop. I have found by experience that I rarely have to turn the antenna & I suspect if I had to do it all over again I would save my money & not buy a rotor!
My loop is an MFJ1788. When I received it I disassembled it, and tightened every screw & nut. Also I re-flowed any suspicious looking solder joints. I also had to do a little reaming out of some holes on the face plate of the remote control so that the push-buttons did not bind on the front panel. Then I played with it on the bench to ensure that it was working properly before I put it back together. I found several loose screws that would have caused me problems..especially those on the shaft that goes from the motor to the capacitor.
On a boat at low power levels you might want to consider a mag loop from Alex PY1AHD. Also see the following web sites for info:
- MFJ1788 product page
- Magnetic Loop Antennas Yahoo Group
- INAC Radio. You may have to click on little English flag to get web site in English.
- Joataman Webpages
- WIMO and Elektronik GMBH
- K5TD Loop Antenna
- Ciro Mazzoni Radiocommunicazione
- Balun Designs Model 1115d – Max Choking 1:1 Balun, 1.5-54 MHz, 5kW. This balun was helpful in eliminating RFI in shack and allowed me to get SWR below 2:1 on 40m.
- GMAntenna
- First Impressions Of The Alpha Magnetic Coaxial Loop Antenna 9-28-2015
- W4OP Loop Antenna (Manual Tuning)
- CHAMELEON ANTENNA Standard Portable HF Loop Antennas F-LOOP
- Chameleon DIY Magnetic Loop Starter kit First Build
- Safety distances from magloops
Hajo says
Hello,
don’t forget the travel loops from John PD7MAA:
http://pa-11019.blogspot.de/2014/08/single-knop-travelloop-65-31-mhz.html
They work perfectly and don’t cost a fortune.
73 de Hajo