A frequency reconfigurable/switchable MIMO antenna for LTE and early 5G applications

In this work, a frequency reconfigurable MIMO antenna for 4G and early 5G applications is presented. The MIMO antenna design consists an array of two radiating/receiving elements positioned diagonally opposite to each other for better isolation (>12 dB) and pattern diversity. Each antenna element in MIMO array has a single module consisting two meandered radiating arms which could be connected or disconnected to the 50 Omega feedline electronically using two PIN diodes to operate in two switchable frequency bands/modes, 2.4 GHz or 3.5 GHz assigned for 4G/LTE and early 5G/Sub-6 GHz wireless communication technologies, respectively. The length of each radiating arm is around half-wavelength at operating frequency of interest (2.4 GHz or 3.5 GHz). The overall size of the MIMO antenna system is 120 mm x 60 mm x 1.52 mm. The proposed MIMO antenna configuration provides a 28.81% FBW (2.0 GHz to 2.7 GHz) and 49.7% FBW (2.57 GHz to 4.27 GHz) in both the resonance modes, respectively. The measured antenna gain values in two switchable frequency modes are 3.7 dBi and 4.2 dBi, respectively with overall efficiency > 60%. A low envelope correlation coefficient (0.0056 at 2.4 GHz and 0.0009 at 3.5 GHz) is achieved. Furthermore, the SAR and hand mode analysis is carried out to verify the performance of the MIMO antenna for mobile handset. The measured ergodic channel capacity of the MIMO antenna has been achieved more than 10b/s/Hz for both the mode.