EM coupled L-band antenna array for secondary surveillance Radar

A novel electromagnetically coupled L band antenna for secondary surveillance Radar (SSR) application is proposed. The printed circuit antenna has an integrated 180 degree PIN diode phase shifter and a two way Wilkinson power divider to eliminate the requirement of an external 180 degree hybrid or a ratrace. The suggested structure is an inverted stacked patch array of 1 × 8 elements. The bottom array patches are inset fed with a microstrip corporate feed network. The inverted top patch elements are electromagnetically coupled with the bottom patch elements. The use of dielectric foam makes the antenna light weight and low cost. A 2:1 impedance bandwidth of 9.4% is achieved with the above geometry in simulation to cover the 1030 ± 5 MHz transmit and 1090 ± 5 MHz receive band. The gain of the antenna is 14 dBi with a 3 dB beam width of 64° and 16° in the two principal planes. Its small size and light weight makes it ideal for portable Radar applications.