I designed this 6m Moxon antenna using EZNEC. The SWR figures predicted are pretty much spot on, with a dip right around 51250. It is pretty flat across the entire 6m band with 1.8 at 50.0 and 1.3 at 54.0 MHz, although model predicts higher at the upper end of the band. See the SWR chart below:
The SWR only follows the model somewhat around 50500 and 51000 kC and then the model diverges and shows a monotonic increase in SWR up to 54000 kC. Both measurements track as the SWR remains below as the frequency goes up.
The gain and F/B are pretty impressive and rivals 3 element beams on gain and very decent F/B of close to 14 dB at 3.5m AGL. The reflector is isolated from the driven elements by a couple of plastic blocks. Overall weight of the antenna is less than 3 lbs. It uses no transformer but will have a more predictable pattern with a choke at the feedpoint. The following plots are for 6m AGL
The front to back is decent and actually gets better at lower heights
The forward gain is best at the height of 6m and the max lobe is at a relatively low takeoff angle.
Tried hitting the RBN with 500W of RF but no luck on getting any hits beaming northeast.
And all of a sudden a pileup - without even hitting a beacon
K0ZK, K3ZA, K1RNO, K1SX, W2SM all in rapid succession.
To those that may be interested in building it - Elements 2, 5 and 6 form the driven element and Elements 1, 3 and 4 for the reflector
All dimensions are in inches:
Element 1 - 14 ga THHN insulated - 76
Element 3 and 4 - 5/16 aluminum tubing - 17 and 3/16 long
Element 5 and 6 - 5/16 aluminum tubing - 12 long
Element 2 - 3/4 square aluminum tubing - 42 long per half driver
The 2 half drivers are separated by an insulation block which is bolted to an insulated angle which is also the mast holder. If you are interested in having me build it for you - contact me at firstname.lastname@example.org. The pattern is very sensitive to the length of element 1 and this length should not be compromised. I almost forgot that the spacing between the driven element and parasitic element is 2 and 3/16 inches. I used 2 blocks of UHMW plastic drilled with 5/16" holes at each end leaving 2 3/16" between the holes as solid plastic.