A "Moxon Rectangle" is a two element beam, where both elements are folded towards eachother. A google search returns some very detailed theoretical analysis of this type of antenna.
I liked this design because it apparently fits on a balcony, thanks to its broad radiation lobe and high F/B ratio. Moreover it is simple to build and tune. So far I have used my VHF Moxon from two balconies with IC-706MKiiG and at 2800 masl with an FT-290R. Here follow some pictures and a screenshot of "moxgen" freeware software.
Figure 1: Screenshot of "moxgen". Shown values are for a 144.3 MHz Moxon.
Figure 2: my VHF Moxon laying on the floor of my entrance.
You can also see the PVC pipe that will support elements and play as a mast.
The little box contains T-shaped PVC connectors.
Figure 3: first time on the air for my VHF Moxon Rectangle.
On the balcony (6th floor, looking towards East).
Figure 4: first time /P with the Moxon and 2.5W from an FT-290R.
Antenna structure and mast are made of 30mm dia PVC pipe, held together with T-shaped
PVC connectors. This no-screw configurations allows to setup your antenna in less than 2 minutes.
Figure 5: further views. I was on Monte Rocciamelone, JN35ME, about 2800 masl.
It was Alpe Adria VHF Contest 2003. My Invicta backpack with plastic structure is a perfect
and lightweight support for the antenna, which ended up at about 2m from the ground.