Low-Cost Wideband Microstrip Arrays With High Aperture Efficiency

Three novel two-dimensional wideband arrays of microstrip E shaped patches are designed for use in a 10% frequency range around the 2.45 GHz ISM band. The proposed arrays are intended to serve as subarray in a switchable outdoor antenna that has to be low-cost and very compact. The scan in the horizontal plane is performed by using switching between six subarrays covering 180 degrees. The main design criterion was a combination of the bandwidth with an aperture efficiency as high as possible, since this allows to minimize occupied space. The design is based on a method of moments algorithm in combination with a particle swarm optimization. CST MW Studio was employed for validation purposes before manufacturing. A very good agreement was achieved between simulated and measured results. The maximum measured aperture efficiencies of the last two arrays are 105% and 86%, respectively, which is considerably higher than what has been reported up to now in literature for wideband microstrip arrays.