A Decoupling Network for Resonant and Non-Resonant Sub-1 GHz MIMO Mobile Terminal Antennas With Improved Compactness and Efficiency

Wai Loon Cheor,Prayoot Akkaraekthalin,Xiaoming Chen,Azremi Abdullah Al-Hadi,Ahmed Mohamed Elshirkasi,Ping Jack Soh,Mohd Faizal Jamlos

doi:10.1109/access.2021.3073835

Abstract

In this work, the design procedure of a new decoupling network for different antennas is presented for mobile terminals operating in the Sub-1 GHz band (from 0.698 to 0.96 GHz). To evaluate its applicability for different resonant and non-resonant antenna types, two antenna elements have been chosen to be decoupled using the proposed decoupling network: a printed inverted-F antenna and a capacitive coupling element antenna. Simulation and measurement results showed that the decoupling network offer promising improvements in terms of impedance matching, port isolation, envelope correlation coefficient (ECC), and total efficiency. In addition, the antennas are also investigated with the ergodic capacity, multiplexing efficiency, gain, and diversity gain (both calculated using maximal ratio combining technique). Due to the contribution of the decoupling network, the ECC of both types of multiple antennas are less than 0.3, with a 30 % improvement in total efficiency and an inter-element spacing miniaturization of 34 %.

Highlights

The multi-input multi-output (MIMO) technology [1] is widely used in wireless communication systems to enhance channel capacity
The results shown by the printed inverted-F antenna (PIFA) is reversed, which is caused by the additional matching network
In this work, a decoupling network applicable for a twoelement PIFA and capacitive coupling element (CCE) antenna in a compact mobile terminal are presented for Sub-1 GHz band

Summary

INTRODUCTION

The multi-input multi-output (MIMO) technology [1] is widely used in wireless communication systems to enhance channel capacity. An excellent trade-off between mutual coupling and the inter-element distance is featured by the decoupling network, while achieving satisfactory total efficiency at the same time These features are advantageous for mobile terminals operating with multiple non-resonant antennas at low frequencies. For both the PIFA and CCE antenna designs, positive values are obtained for Im{Y21}, and capacitors have been implemented as the reactive element in the decoupling network. Both antennas in this work are dimensioned at 23 x 20 mm (0.116 x 0.1 λg).

SNR H

Findings

CONCLUSION