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G4AXX

15m Monoband Yagi


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Dimensions
Director 6.556m
Driven 6.930m
Reflector 7.116m
Dir-Driven spacing 2.170m
Driven-Ref spacing 2.587m
Boom 4.88m. 50.8mm aluminium TV mast
Weight 15kg


These dimensions were derived from "HF Antennas For All Locations", Les Moxon G6XN, 2nd Edition 1993, Figure 5.25, page 95.

This yagi has been optimised as a no-compromise contest monobander. It's also been designed to be very easy to put up. All the elements can be assembled without tools, the whole antenna can be on the tower in about 15 minutes and there are no loose parts to get lost :-)

Click on a thumbnail below to see a larger picture.

Close up view of the "bayonet" (BNC-like) method of connecting the element sections together.

Gamma capacitor and the 6 half-elements.

Feed-point centre section. The elements are assembled without tools, just push and twist.

Feedpoint and detail of Gamma match.

Gamma match shorting strap, (red tape marks the 50 Ohm position. Again no tools needed, just push-clips.

Gamma match. The Gamma capacitor is a "trombone" arrangement made from aluminium tube sections insulated with 3 layers of heatshrink tubing.

Using this antenna with an FT1000MP, Mark G4AXX, using the club's contest callsign M4R, achieved a new all-time record for England in CQWW 2001 in the "SOSB 21 LP" section.

Here's how the CQWW SSB all-time records for England looked at the time. Click here to check out the records as they currently stand, on http://www.cqww.com/records_ph_europe.htm.

2D Elevation plot of the beam when mounted 30m above ground. The gain in free space is 9.3dBi, but at this height above ground, the ground reflection reinforces the direct path to produce a gain of 14.89dBi 6 degrees above the horizon.

2D azimuth plot showing the beamwidth, 61.3 degrees, and the front to back ratio, 17.2dB

The 3D plot of the antenna

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