2 Meter Yagi Antenna

Down on the farm there are not too many VHF repeaters that I can get into. So I thought I would make a beam antenna and see if I could get into some 2m repeaters around Melbourne (about 160 km away).

Here it is clamped to a star picket about 2meters off the ground, pointed roughly toward Melbourne.

 

2m Yagi Testing

2m Yagi Testing

Materials

  • 3m x 25mm square aluminium tube $25
  • 3 lengths of 10mm round tube $17
  • screws and copper saddles $10
  • 12mm tube x 1m $2

The copper saddles are probably not a good choice as they will cause galvanic corrosion with the boom and elements. I plan to either insulate the copper or use some plastic saddles.

For the feed, I hammered flat, one end of some 12mm aluminium tube (about 13cm long) and slid the 10mm tube into it. These were screwed some plywood. The coax was screwed attached to the screws. This is a bit rough but worked surprisingly well, the VSWR was about 1.2.

Design

I studied the ARRL antenna book, and a few yagi design websites. In the end I spent some time adjusting the element lengths to get a broad VSWR response. This is the NEC file I came up with

CM 2M YAGI 8 ELEMENT

CM TAG NS X1 Y1 Z1 X2 Y2 Z2 RAD

CE

GS 0 0 1.00000E-03 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

GW 1 15 0.00000E+00 0.00000E+00 -5.03500E-01 0.00000E+00 0.00000E+00 5.03500E-01 1.00000E-02

GW 2 15 0.00000E+00 3.12000E-01 -4.77500E-01 0.00000E+00 3.12000E-01 4.77500E-01 1.00000E-02

GW 3 15 0.00000E+00 4.48000E-01 -4.38000E-01 0.00000E+00 4.48000E-01 4.38000E-01 1.00000E-02

GW 4 15 0.00000E+00 7.00000E-01 -4.33000E-01 0.00000E+00 7.00000E-01 4.33000E-01 1.00000E-02

GW 5 15 0.00000E+00 1.04900E+00 -4.28000E-01 0.00000E+00 1.04900E+00 4.28000E-01 1.00000E-02

GW 6 15 0.00000E+00 1.57000E+00 -4.23000E-01 0.00000E+00 1.57000E+00 4.23000E-01 1.00000E-02

GW 7 15 0.00000E+00 2.15300E+00 -4.18500E-01 0.00000E+00 2.15300E+00 4.18500E-01 1.00000E-02

GW 8 15 0.00000E+00 2.77700E+00 -4.15000E-01 0.00000E+00 2.77700E+00 4.15000E-01 1.00000E-02

GW 9 15 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 3.00000E+00 0.00000E+00 2.50000E-02

GE 0 0 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

EX 0 2 8 0 1.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

FR 0 11 0 0 1.20000E+02 5.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

NH 0 0 0 0 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

NE 0 10 1 10 -1.35000E+00 0.00000E+00 -1.35000E+00 3.00000E-01 0.00000E+00 3.00000E-01

RP 0 19 37 0 0.00000E+00 0.00000E+00 1.00000E+01 1.00000E+01 0.00000E+00 0.00000E+00

EN 0 0 0 0 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

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