( = citation from the official "Radio Jove"-website: http://radiojove.gsfc.nasa.gov/index.html )
The advantage of the "Moxon"-antenna in comparison with the double-dipole-antenna in the description on the Websites of "Radio Jove" consists in its smaller size and only one feed cable instead of two feed-cables and one power splitter. The antenna pattern is almost the same.
The antenna is calculated for the centerfrequency of 20,1 MHz.
On the web you can find more than one calculator for "MOXON" - antennas.
I calculated with the following one: w4.vp9kf.com/moxon_design.htm
The data was obtained from the "MMANA-Gal" - Antenna Simulation Programm for a hight of 7 meters (= 23 feet):