My 4 sq did pretty well in the ARRL DX contest and also in CQ 160 SSB. But it was noisy. Perhaps because the elements were not tuned, with resonances from 1.78 to 1.84 MHz
I decided to tune the elements to around 1.83. The impedances were:
42 Ohms for NE
40 Ohms for NW
32 Ohms for SE
22 Ohms for SW
Weird. Did NE have too few radials? I added an 8 extra 60ft radials, and the impedance dropped to only to 39 Ohms. Not much.
And why the impedance of the SW element was so low?
The elements for SE and SW were in the radial field of my shunt fed tower and the radial field of 4 sq for 80. So perhaps they behaved as having more radials. The SW element was close to the shunt fed tower tuned for 160m and apparently coupled. After shorting the shunt fed, which detuned the tower, the SW impedance increased to 32 Ohms as in the SE element. Hurrah!
Due to unbalanced elements, F/B is only about 10 db although. This is perfect for contesting as beaming in one direction still leaves some signal in the other directions. For better directivity there are beverages used with the 4 sq in diversity mode.
The 4sq controller by DXE has an omnidirectional mode, seemingly perfect for general contesting. But initially it had a resonance at 1.70 and SWR jumped to 2.5 at 1.84. I contacted DXE and they claimed that the omni mode is for receiving and occasional transmit. After tuning all elements to 1.83, SWR around 1.83 is about 1.5. But the resonance is narrow, as opposed to nearly flat SWR in the 4 sq mode.