05 April 2009

Revolutionary Yagi Antenna Feed System

Justin Johnson G0KSC, says that he has pioneered a revolutionary new feed system for the Yagi directional beam antenna, which will see it's Debut in the next issue of DUBUS - the serious magazine for VHF and up amateur radio www.dubus.org.

Justin writes:
Whilst there are many benefits seen with the new system, the most important break-through is the suppression of the age old problem of unwanted side lobes within longer Yagi designs.

The feed system (which does not consist of a dipole and no, it is not a Quagi!) has 2 different feed points. Whilst the antenna needs re-modeling in order to change from one to the other, different characteristics are seen from each method. The first enhances the bandwidth capabilities of the Yagi and presents never-seen-before ultra low return loss, excellent gain and front to back ratio, whilst the other provides more traditional OWA (Optimised Wide-band array) style bandwidth with good improvements in forward gain and massive improvements in front to back ratio.

What people say, 'This could be a turning point in the development of the Yagi Antenna'
Popa, YU7EF - World renowned Yagi antenna designer/engineer - www.yu7ef.com 'Justin, Indeed this looks like a unique and winning design!', Joel R. Hallas, W1ZR - Technical Editor, QST Magazine. 'Hi Justin, Many thanks for the plots, these diagrams look really beautiful! I have never seen such F/B and low sidelobes for a Yagi before', Joe CT1HZE - DUBUS Magazine

Benefits of the new design
Whilst going to press, experiments are still being conducted with the new Yagi. However, the new feed adds a number of very interesting characteristics to the Yagi which when focus is
applied to optimisation, excellent not-seen-before Yagi performance is the result. The list so far consists of the following :
  • Superior Front to Back Ratio with very high suppression of unwanted lobes
  • Extended/alteration of 'ideal' boom length
  • Exceptional clean pattern performance
  • Ultra-wideband characteristics
  • 50 Ohm impedance – no matching required
  • Easy fine-tuning of feed arrangement itself
More information and plots at: http://www.g0ksc.co.uk/latest-design.html

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