As 1296 MHz receive only antenna I have chosen to try a biquad (or dual-quad). It is composed of two full-size quadriangular loops (23cm perimeter each), set electrically in parallel and "touching" at one corner, the feedpoint.
Mechanically speaking, a 23cm biquad is simple to build, requiring a thick copper wire (1mm diameter or so) and a large reflector, say, 20x30cm, like a copper clad board. Loops-to-reflector distance should be 1/8th wavelength, which is about 2.9cm.
2.9cm ... that's the tricky part for someone like me that is not equipped to do mechanical work. I prefer what can be done with the soldering iron. So I wanted to understand what would happen to my biquad if the element separation would be of ~1.5cm, that is the height offered by a BNC female head screwed on the PCB/reflector element.
Online resources suggest that a change in spacing modifies forward gain and F/B ratio, but impedance doesn't vary too much. Anyway I have no means to measure SWR at 1200 MHz, so all I am interested in is a confirmation of the gain, amount and direction.
An MMANA simulation is on the way...