Portable lightweight 4-Element 2m DIY Antenna (SOTA)

2m Yagi2m Yagi

Here is the description of one of the antennas I frequently use during SOTA activations.

The antenna is based on a design by DK7ZB and former NUXCOM.

It is build from basic materials:

• Aluminium welding rods with diameter 4 and 3,2 mm from Ebay
• Insulation pipes 20 and 25mm* diameter (16mm for the loading coil)
• PVC clamps
• 50 Ohm coaxial cable (eg. RG174 or RG 188)
• Insulation tape
• Luster terminals to extend the aluminium welding rods**

* For FM use the polarisation is vertical. I mount the antenna on hiking poles. In order for the antenna to be (more or less) free from interfering with the hiking poles I built an extension with 25mm insulation pipe, see pictures below. 

**My initial version was around 1,1m long when disassembled but this was too long for more serious hikes since it could be mounted only outside on the rucksack. Now I have cut all radiation elements so they can be mounted together with luster terminals. Also the extension pipes (25mm) and the boom itself is cut in appropriate places and held together with sleeves. When disassembled the whole packages now measures around 65cm in length and fits into my rucksack.

Construction details

Terminals for cut radiators.Terminals for cut radiators.

Above: For the smaller package size the rods are simply cut and then mounted together with the luster terminals. For the rods themselves I did drill a hole of 3 mm into the PVC clamps, that way the 3,2 mm rods are quite hard to push into to holes but once there they do not need additional fixation. 

Wooden "mounting plate" for the active element.Wooden "mounting plate" for the active element.

Above: For the radiator (4mm) I used a piece of wood. The radiator rods are attached to luster terminals which in turns are attached to the piece of wood with small screws. The loading coil is attached to the piece of wood as well. The antenna design is 50 ohm, the loading coil is used to act as a sheath current filter. The whole plate is again attached to the pipe with a PVC clamp.

"Mast" made from velcro tape and hiking stiks."Mast" made from velcro tape and hiking stiks. The antennaThe antenna

For the mast as mentioned I use the hiking poles, see above. The whole SOTA package, including the handheld transceiver, 5m cable, notebook and pen, the velcro-tapes and a screwdriver weighs around 1,4kg.

The maximum distance I achieved with this setup (4 Watt) was 361km.