Antenna Plans

2×3 2m/70cm Cross element yagi build instruction – compact that works

Compact satellite communication antenna

If you’re a fan of satellite monitoring (hunting for birds) as they call it, you probably want a bigger antenna with lots of elements for good contacts. Long antennas are good for satellite contacts with low elevation angle now the downside of those antennas are the lengths and they are cumbersome to work with specially if you’re home brewing and the materials available are not light enough. Each element will add up to the weight and will easily become unwieldy for hand operations holding the antenna on one hand and on the other the radio unless you are muscular then that would be easy. For casual contacts and mobility a compact antenna will get you where you want to go and still hunt for satellite with high elevation passes if you’re a fan of long distance and low elevation then this may not be for you.

Antenna measurements and mounting guide

Download the PDF document here

Materials list

1″ X 1″ Rectangular Aluminum tubing for the boom (cut to length)
3/8″ Aluminum tubing for antenna elements (cut to length)
2pc SO239 connector
#12 AWG Copper wire with insulation (12″for Gamma match)
Soldering iron
5pcs Stainless steel nuts and bolts 30mm length 3mm diameter
6pcs Stainless steel nuts and bolts 30mm length 3mm diameter
1, Butterfly nut and 1 bolt 18mm length 3mm diameter
Aluminum plate 0.5mm thickness
Collapsible tube (shrinkable tubes)

4Nec2 data analysis

Antenna gain, beamwith and predicted pattern spit out by 4Nec2 antenna modelling software

2×3 Cross Yagi VHF side – VHF side data was optimized using 4Nec2 antenna modelling optimization option SWR is spot on at 1.1:1
2×3 Elements cross yagi UHF side – don’t worry with the SWR data being spit out by 4Nec as you still need to match the UHF antenna for optimum SWR. The gamma matching can bring it down as you will see on the vector impedance analyzer.

Vector impedance analyzer frequency response data

This is the result of impedance analyzer testing for 2×3 elements cross yagi. Obtainable SWR is around 1.2:1 at the center frequency antenna reflection coefficient is at -23dB at VHF and -19dB at UHF. Pretty usable antenna, as you can see as well, the data spit out by 4Nec2 with regards to SWR on VHF side is close enough, I just directly cut the elements and assemble it with respect to the antenna measurement for the UHF side it was compensated with the use of gamma matching and correct length of the phasing harness. The capacitance of the gamma match when un-attached to the antenna assembly is around 10nf (0.01uf) and 20nf (0.02uf) respectively for UHF and the VHF side as measured using capacitance meter.

Actual testing of the antenna

This is actual testing of the antenna see the video around 2:30-2:38 I called out DV2JHA unfortunately we didn’t manage to confirm a successful QSO until the satellite signal started to fade out. Over all it’s a successful build.