Design of quad band 2×2 planar microstrip array

The design of a planar 22 array for multiband operation is proposed and investigated. A 22 planar array is fabricated and simulated in which a defected ground structure rectangular patch with dual inverted L-shaped protrudent strip fed with a cross shaped strip line used as an radiating element. The H-shaped feeding network used to feed a quad-element block in place of regular corporate feed to increase the gain and bandwidth of the patch antenna elements. Measured impedance bandwidths of the quad band 22 planer microstrip array are about 445 MHz at first band (2.08-2.53 GHz), 150 MHz at second band (3.25-3.4 GHz), 150 MHz at third band (3.73-3.88 GHz) and 840 MHz at forth band (4.59-5.45 GHz), with radiation patterns and gains of the array remaining nearly constant over these bandwidths. The directivity of quad band planar array about 5.2, 12.99, 10.12, and 11.74 dB are obtained at the I, II, III and IV resonant frequency, respectively.