Sunday, February 17, 2019

The VK2ABQ multiband mini beam

Before the Moxon Rectangle became popular there was the VK2ABQ beam.

Like the Moxon, this was basically a two element yagi with the ends bent in to reduce turning radius. As originally presented, in a 1973 Electronics Australia magazine, the VK2ABQ had wire elements for 10, 15 and 20 metres. Its square shape make it look like a rotary clothes hoist.  Elements were bent in towards themselves, with large coat buttons providing the spacing.

This development was done before amateur access to antenna modelling programs and antenna analysers. Test equipment generally available then would have been little more than noise bridges, RF ammeters, signal sources and field strength meters.

The VK2ABQ allowed people who didn't have the room or money for the standard triband trapped beam to have something of almost similar performance in a smaller space for less. The antenna became more widely known through Pat Hawker G3VA's Technical Topics column in RadCom. The critical coupling technique it used was refined by Les Moxon G6XN to produce what we now know as the Moxon.

VK2ABQ as built by ZS1JHG
Modeling and understanding small beams (including VK2ABQ) by W4RNL
Vertically polarised VK2ABQ for 50 MHz by GW0GHF
Critically coupled antennas by VK6APH/G3WXO

PS: Want to read more about antennas? Consider this selection of antenna books. They are affiliate links meaning that I receive a small commission (at no extra cost to you) if you decide to purchase.

1 comment:

  1. More fun things I never knew!!!! Thanks....


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