Nice propagation to test the Moxon antenna

Lucky me!!! No better way to test the homemade 10m Moxon antenna then with current conditions. Best propagation since 2003, definitely! I took the chance to do one on one tests, and results are a bit surprising in a positive way. But first of all for the right comparison:

The 2 element copper wire Moxon has horizontal polarization, is mounted at  almost 13m from the ground and is centred at 28.500 MHz. The ¼ wave aluminium vertical with four sloping copper wire radials has vertical polarization. It is centred at 28.500 MHz and the feedpoint stands 11m from the ground. At the centre frequency SWR of both antennas are very close to 1:1 and both resonant, measured with an MFJ 259B analyzer. The Moxon is fed with RG-213 coax and a few meters of RG-58 near the rotor. The vertical is fed by RG-213 coax, which is 4m shorter in length than the Moxon’s coax. Both antennas are mounted on top of the roof of a brick house in a quite dense populated area, with quite high ground water levels (estimated conductivity is 3 mS/m).

First serie of comparisons is gain over different path lengths (e.g. different radiation angles) using F2 propagation. For the high radiation angles I choose stations in Greece, Bulgaria, Russia, Southern Italy, Southern Spain, Finland and Norway, all path lengths of about 1800-2100km. For the low radiation angles I choose longer single and double hop paths to stations in North America, Africa and Asiatic Russia with typical single hop distance of >3000km.

In all cases the Moxon was a winner, with at least 6dB (1 S-point) up to 15dB (2.5 S-point) gain over the vertical. There was no noticeable difference in gain between low and high radiation angle, but interesting was the gain of over 20dB (> 3 S-points) over the vertical on certain paths in northern direction like Pacific and Norway. I do not have a good explanation for this.

The front/back ratio of the Moxon is average about 20-25dB (3-4 S-points). Remarkable was the front/side ratio which was average 15dB, much lower than I expected and measured before! But the actual “null”  on the sides was not at a 90° and 270° angle from the front but more at a 60-70° and 290-300°angle, suggesting that at 90° and 270° angle from the front there are two small lobes instead of a null. These side lobes could be caused by the vertical antenna that stands at a 1/2 wave distance from the Moxon. What I will probably do is to ground the vertical, or make it not resonant when I switch over to the Moxon and vice versa. This way none of the antennas should interfere as a parasitic element.

73 de PA9X Jean-Paul Suijs