WARC Bands

A simple homemade multiband dipole

 

The WARC bands are not commonly used by many hams who prefer to stick to the tried and tested 5 band combo. This is a shame as the WARC bands are usually very good for the DX chasers and provide a haven during periods of contest activity on the other bands.

What are the WARC bands you ask? There are three bands which were granted by the World Administrative Radio Conference in 1979, and were released for use in the early 80's.

They consist of 30 meters (10.10010.150 MHz), 17 meters (18.06818.168 MHz) and 12 meters (24.89024.990 MHz)

Region 3 band plans

24.89024.920 24.920-24.9295 24.9295-24.9305 24.940-24.990
               2 kHz max BW

 

18.068-18.095 18.095-18.105 18.105-18.1095 18.1095-18.1105 18.1105-18.168
                    all modes

 

10.100-10.140 10.140-10.150
   

 

Key for Band Plans

  = CW only
  = CW, narrow band digital ( <= 500 Hz )
  = CW, narrow band digital ( <= 500 Hz ), wide band digital
  = Beacons

(info from Wikipedia)

 

I decided a three band parallel dipole would be good enough and easy to make. The wire I used is stranded copper wire. You should make each dipole slightly longer than the calculated resonant length and wind the excess wire back along itself. When you tune up the dipoles start with the 30m one first and once you have found the resonance, do the same procedure with the others in sequence. You may need to shorten or lengthen each dipole and the process can become tedious!

The dimensions I eventually settled on, after tuning up, are shown in the diagram below. One side of the multi dipole is shown. Small lengths of wood were used as spreaders and you could also use plastic pipe or any other available insulating material. The center piece is a small section of plastic pipe and the wires connect to the coax inside. I used a small choke balun to isolate the feeder. The resonance will be affected to a degree by the height of the antenna above ground. My dipoles are about 7m above ground and run from the roof down to a tree in the field.

A view of the dipole in the air.

The small choke balun fitted at the center

 

Results to date have been very good with DX worked on both CW and digital modes on all three bands with not more than 100W output. The antenna is simple to make and doesn't take up much room, so if you are not already on the WARC bands this antenna will be a good start.

Some good information on designing multiband dipoles for various band combinations can be found at....

http://www.hamuniverse.com/multidipole.html

 

DU1GM 2012