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Showing posts from March, 2019

Driving A 900 MHz Quad Patch Array Antenna

A Circular Polarized Quad Patch Array for the 900 MHz ISM Band Driving a patch array antenna is a tricky and multidisciplinary affair - a combination of electrics, magnetics and mechanics - where theory meets reality.  Patch antennas are useful between about 1 and 5 GHz.  Below that, they are too big and above that, too small to be practical for the manufacturing tolerances of a hobbyist.  For L, S and C-band, a radio amateur can use patches with good effect, using not much more than tin snips and a nibble tool. 902-928 MHz ISM Band LCP Quad Patch Antenna The patch antenna theory can be explored with a simulation program such as NEC2: You could make an array with any number of patches, but more than four would be a whole lot of hassle.  A SAR radar antenna may have 300 tiny little patches.  However, a two by two is about the limit of my patience. Any piece of metal within half a wavelength of an anten