A circularly polarized multiple‐input multiple‐output (MIMO) antenna is presented for global system for mobile (GSM) (710 MHz) and lower long term evolution (LTE) (900 MHz) frequency bands. The antenna consists of four ports with four impedance transformers on the bottom substrate and elliptical rings on the upper substrates. Impedance transformers include open stub and irregular microstrip lines in order to control impedance matching and resonant frequencies. Two upper substrates that contain orthogonal elliptical rings cause the circular polarization property of the proposed antenna. The results of measurement for the presented antenna show its performance with S‐parameters of less than −10 dB in the frequency ranges of 699‐750 MHz for GSM and 880‐1115 MHz for lower LTE applications. Also, the gain and radiation efficiency are higher than 5dBi and 70%, respectively.

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In this paper, an array antenna fed by a novel double layer 3 × 3 Butler matrix for Ku‐band application was presented. An antipodal Vivaldi antenna (AVA) with dielectric lens was suggested as radiating elements. AVA has a broadband specification along with directive stable patterns at operational bandwidth. Combinational structure of substrate integrated waveguide topology by modified radiating element (AVAs) results to miniaturized size and acceptable radiation efficiency in whole of Ku‐Band. Presented array covers frequency range of 13–17.5 GHz (30%) with average gain of 14.2 dBi. The proposed beam‐steering antenna with compact size and good performance is capable to cover an angle range from −39 to 38° in whole operation frequency. This structure with unique configuration and specification can be a good candidate for beam‐forming application for wireless devices.