Eight-Element Compact UWB-MIMO/Diversity Antenna with WLAN Band Rejection for 3G/4G/5G Communications

Abstract

An eight element, compact Ultra Wideband− Multiple Input Multiple Output (UWB-MIMO) antenna capable of providing high data rates for future Fifth Generation (5G) terminal equipments along with the provision of necessary bandwidth for Third Generation (3G) and Fourth Generation (4G) communications that accomplishes band rejection from 4.85 to 6.35 GHz by deploying a Inductor Capacitor (LC) stub on the ground plane is presented. The incorporated stub also provides flexibility to reject any selected band as well as bandwidth control. The orthogonal placement of the printed monopoles permits polarization diversity and provides high isolation. In the proposed eight element UWB-MIMO/diversity antenna, monopole pair 3−4 are 180 • mirrored transform of monopole pair 1−2 which lie on the opposite corners of a planar 50 × 50 mm 2 substrate. Four additional monopoles are then placed perpendicularly to the same board leading to a total size of 50 × 50 × 25 mm 3 only. The simulated results are validated by comparing the measurements of a fabricated prototype. It was concluded that the design meets the target specifications over the entire bandwidth of 2 to 12 GHz with a reflection coefficient better than −10 dB (except the rejected band), isolation more than 17 dB, low envelope correlation, low gain variation, stable radiation pattern, and strong rejection of the signals in the Wireless Local Area Network (WLAN) band. Overall, compact and reduced complexity of the proposed eight element architecture, strengthens its practical viability for the diversity applications in future 5G terminal equipments amongst other MIMO antennas designs present in the literature. INDEX TERMS Band rejected, compact, diversity, envelope correlation coefficient , multiple input multiple output, ultrawide band, 5G communication, 5G terminal devices. I. INTRODUCTION W IRELESS broadband communication system such as Worldwide Interoperability for Microwave Access (WiMAX (3.4 to 3.6 GHz)), large capacity Microwave Relay Trunk Network (4.4 to 4.99 GHz), and Wireless Local Area Network (WLAN signals in 5.15 to 5.35 and 5.75 to 5.8225 GHz bands), impose a limited power spectral density of the low power and a high data rate

Compact Wideband MIMO Diversity Antenna for Mobile Applications Using Multi-Layered Structure

“…The results of Figure 12 were similar to those above: over the band 4.78-8.40 GHz (3.7 GHz bandwidth), S11 and S22 are better than −10 dB. The values of S12 and S21 are all better than −21 dB over the required bandwidth, which exceeds the performance of the published works [18][19][20]. The mutual coupling S parameters shown in Figure 11b are in close agreement with each other, but the measured and simulated values differ by a margin which averages approximately 8 dB.…”

“…The mutual coupling S parameters shown in Figure 11b are in close agreement with each other, but the measured and simulated values differ by a margin which averages approximately 8 dB. However, this disagreement is in favor of the measurements, which surprisingly show better performance than the simulation: the simulated values are below −18 dB across the desired band and the measured values below −30 dB, meaning that the device easily satisfies the requirement in the FCC Ultra-wideband standard of mutual coupling better than −15 dB [18].…”

“…Constraining mutual coupling in a narrow-band antenna is relatively straightforward, but the greatly increased degrees of freedom in a wideband one makes it very challenging in such a case, especially if size is also constrained. A number of past studies have attempted to address this problem, with varying degrees of success [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In [9][10][11][12][13][14][15][16][17][18], various decoupling structures were suggested to be interposed between several symmetrically placed elements to enhance isolation between them.…”

“…A number of past studies have attempted to address this problem, with varying degrees of success [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In [9][10][11][12][13][14][15][16][17][18], various decoupling structures were suggested to be interposed between several symmetrically placed elements to enhance isolation between them. These methods are using Electromagnetic Band Gap structure [9], adopting distinct patterns and polarization of the radiator [10,11,14], defected or modified ground plane [12,16,17], neutralization strip [13,20], embedded periphery slot [22], parasitic stubs [15,18] and metamaterial [19,21].…”

“…In [9][10][11][12][13][14][15][16][17][18], various decoupling structures were suggested to be interposed between several symmetrically placed elements to enhance isolation between them. These methods are using Electromagnetic Band Gap structure [9], adopting distinct patterns and polarization of the radiator [10,11,14], defected or modified ground plane [12,16,17], neutralization strip [13,20], embedded periphery slot [22], parasitic stubs [15,18] and metamaterial [19,21]. In [23][24][25][26], differently structured antenna elements were combined to achieve pattern diversity.…”