Moxon for 2meters

 

July 2014 – Back  around Nov 2013,  I put together a moxon antenna for 2m.   A moxon is a 2 element folded beam which forms a rectange.    The driven element is out in front, and the reflector is in the rear.  The feedline runs in at 90° to the reflector and connects directly to the driven element – center to one dipole element, shield to the opposite dipole element.  It’s generally held to be a somewhat directional antenna with a modest amount of gain but with a pronounced front to back ratio.

CALCULATIONS FOR #12 THHN cu wire

A  29.17″ long dimension
B    4.05″  driven element short component
C    1.17″   driven to reflector gap
D    5.56″  reflector element short component
E   10.78 short dimension

Using 50Ω line I get  1.3 SWR at 147.0 mhz  and 1.4 SWR at 144 mhz.

On receive I measure a F:B  ratio  in a range from  12  to 20 dB – in line with the known characteristic of the moxon.

Comparisons with the Ed Fong j-pole.  For the nightly 2m 146.88 net  receive signal is +50 dB –  same as the  j-pole +50 dB.  On reverse I get stations readable on the moxon, unreadable on the j-pole, indicating the moxon has enough gain over the j-pole to be significant at weak signal levels.

~ by marksun on July 9, 2014.