28. December 2009 · Comments Off on 20m 2-element light-weight Yagi · Categories: Antennas, Contest · Tags: ,

This antenna was designed for the CQ WW CW 2009 at EA8URL. The Bavarian Contest Club took part in the M/M class with a team of German operators. The antenna plans included a second 20m antenna to work both USA and Europe in the day time. Because EA8URL has only one 20m yagi we had to bring another 20m yagi with us. Most important mechanical requirement: Airplane suitable as ‘sport luggage’ (so no extra charge). All elements are made out of fishing rods with an insulated copper cable fixed on the rods by cable ties. Both fishing rods and cable (DX-Wire ‘FL’ from DK1RP) are UV resistant. The boom or so called ‘fishing rod support’ is made of a telescopable aluminium tube.

Technical data:

Boom length: 3.56 m (11.68 ft)
Boom diameter: 40/35/30 mm (1.58/1.38/1.18″)
Boom wall thickness: 2 mm (0.08″)
Element length: 2 x 5 m (2 x 16.4 ft) fishing rod
SWR: 1.25 – 1.15 – 1.35 (14.000 – 14.160 – 14.350 MHz)
Gain: 10.6 dBi @ 14.15 MHz (10 m above moderate ground*)
Power handling: Alpha 87A full output can’t destroy it
Weight: 5.2 kg
Shipping weight: 5.8 kg (12.8 lbs)
Shipping dimensions: 0.11 m x 1.2 m (4.22″ x 47.24″) round tube
* ground conductivity = 0.003 S/m and relative permittivity = 4

Pictures and SWR curve: http://5tx.de/load/ham_radio/20m_2ele.pdf

NEC File (with length of the elements): http://5tx.de/load/ham_radio/20m_2ele.nec

Please note that the simulated element lengths are too long in reality if you use the above mentioned DX-Wire. This could be different if you take other wires with a thicker insulation.

The ‘TuiFly’ Airline Company accepted this antenna as ‘sport luggage’ in a wastewater pipe. Those pipes are cheap and robust and well suited for transportation of glass fibre reinforced plastic.

Overall cost of this antenna is about 90 €. In detail:

Aluminium tubes: 15 €
Fishing rods: 52 €
Wire: 8 €
Bits and pieces: 15 €

The Relative ground permittivity is expressed in Farads per meter.

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