A Microstrip Patch Phased Array Antenna With Parasitic Elements And Reactance-Tuned Coupling

A new approach to parasitic phased array antennas is presented. A symmetric two-layer, single input inexpensive three-element array at 1 GHz employing varactors as tuning mechanisms is designed, fabricated and measured. The driven element is mutually coupled to two parasitic elements in the H-plane, and the mutual coupling is tuned by open-circuited microstrip stubs on the feed layer. The varactors are used to break the symmetry of the structure, resulting in beam scanning, and to maintain resonance at 1 GHz. A symmetric scanning range of 20 to +20 is measured with maintained impedance matching and radiation pattern integrity. The low cost of this array is advantageous to applications in point-to-point communication systems, weather and target tracking radar systems. © 2011 IEEE