MONSTER YAGI FOR 20M

A 5 element wide spaced yagi for the 20m long path to Europe was installed at ZL6QH in May 2005. A photo of this “monster” antenna is shown above. Brian ZL1AZE can be seen on a ladder making the final adjustments to the open wire feeder connections, just before darkness arrived!

The yagi has a 16m boom length and is approximately 15m AGL on the Quartz Hill ridge. It is a light weight and rugged design, using aluminium tubing and ropes, as shown in the detailed drawing below. Conventional yagi designs with self supporting elements are not employed at ZL6QH as they would not survive the severe storms that are regularly experienced at the station.

Like other ZL6QH antennas, the antenna is fed with a 600 ohm open wire feed line. The feed line is matched to the antenna using a “3 wire” folded driven element.

The software model for the antenna shows that the maximum gain of the antenna (at 15m AGL) is close to 15 dBi at an elevation angle of 18 deg. The SWR is less than 1.5:1 over the range 14.0 to 14.3 MHz.

Recent tests in the 2005 CQ WPX CW contest indicate that the yagi offers performance similar to and often better than that provided by the existing Europe long path vee beam (300m legs).