Low‐cost low‐sidelobe microstrip array with circular polarization

A low‐cost low‐sidelobe microstrip array antenna with a symmetric main beam of circular polarization (CP) is introduced. The array antenna has a coplanar feed network to excite a Chebyshev current distribution in the horizontal direction and a uniform distribution in the vertical direction of a 4 × 3 elements array. The CP operation is realized by using the corner‐fed quasi‐square patch elements. Measured results show that the array has a sidelobe level (SLL) of −21 dB in the horizontal plane, the half‐power beamwidth of 27° for two main planes both and the axial ratio of below 3 dB within the main beam. Its return loss is less than −10dB for the impedance bandwidth of 40 MHz. Its measured gain reaches 13.9 dB at 2.55 GHz. It is a low‐cost low‐sidelobe design with thin profile, simple structure, CP operation, and symmetric main beam, suited for the radio frequency identification (RFID) readers and other wireless systems. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2384–2386, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23687