Radiation Properties Improvement of 1 × 4 Array of Wideband Printed Antenna Supported by AMC Surface for Vehicular MIMO Systems

Abstract

AbstractA 1 × 4 array of printed dipole antenna (PDA) with a broadband rhomboid artificial magnetic conductor (AMC) is introduced. A suggested PDA using a pair of microstrip dipoles with unequal arms excited by a T‐shaped microstrip feedline expands the bandwidth in the measured range of 5.27–6.74 GHz. Then, the suggested 3 × 3 AMC reflector is inserted into the PDA to exhibit −10 dB measured impedance bandwidth from 4.20 to 7.11 GHz for WLAN and WiMAX applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 46.72%, enhanced gain up to 8.4 dBi, and excellent impedance matching with unidirectional radiation patterns. The novel AMC unit cell operates at 6.20 GHz with an AMC bandwidth of 5.09–7.21 GHz. Also, by loading a 3 × 8 AMC periodic array on a FR4 substrate with 3 mm thickness underneath the four‐element array of PDA with a gap distance of 3 mm, a low‐profile wideband structure with enhanced radiation properties is achieved. The measured S‐parameters show the broad bandwidth from 4.26 to 7.28 GHz with enhanced gains and efficiencies of all elements. Besides, the suitable isolation between the array elements of more than 30 dB for multiple‐input multiple‐output (MIMO) systems is achieved by applying various polarized directions of PDAs and loading the 3 × 8 periodic AMC reflector. Finally, the proposed MIMO design introduces remarkable advantages of good size reduction and bandwidth enhancement, low‐profile antenna with high stable gain, high efficiency and large isolation, and unidirectional radiation patterns with reduced backside direction.