Design of a Novel Circularly Polarized MIMO Antenna with Enhanced Isolation for Ultra-wideband Communication

Abstract

In this paper, we propose a circularly polarized (CP) ultra-wideband (UWB) MIMO antenna. Compared with common linearly polarized (LP) UWB antenna, the proposed antenna can excite circular polarization (CP) mode for WLAN communication and its impedance bandwidth can also fully cover UWB spectrum. It consists of identical circularly polarized antennas. Each unit adopts circular monopole with extended orthogonal rectangle patch to realize broadband and symmetrical rectangular ground with slot in the diagonal of each antenna unit to achieve circular polarization for WLAN band. It has a very compact size and the dimension is 25 × 51 × 0.8 mm3. The impedance bandwidth of the proposed antenna is from 3.1 GHz to 13.5 GHz, with average gain of 4 dBi, fully covering UWB bandwidth and enhanced by 38%. At the same time, circular polarization is achieved by embedding two symmetrical rectangular slot structures in the two opposite corners of every antenna unit. The extended orthogonal rectangle patch is introduced to enhance impedance bandwidth and broaden axial ratio (AR) bandwidth. The measured 3 dB axial ratio (AR) bandwidth is 1.8 GHz (4.7-6.5 GHz), fully covering WLAN band. Meanwhile, the slit slot between antenna units and rectangular openings are introduced to achieve high isolation. The proposed antenna keeps ECC (envelope correlation coefficient) below 0.01, which showing good isolation and diversity characteristics. The proposed antenna can simultaneously operate in the UWB spectrum and exhibit circularly polarized (CP) radiation characteristic in WLAN.

Slots and stubs incorporated annular ring-shaped compact microstrip antenna with circular polarization characteristics for wireless UWB communication systems

“…The performance comparison table clearly indicates largest operating bandwidth, wide ARBW, good gain and high radiation efficiency of the suggested radiator as compared to other designs proposed in . Additionally, the suggested antenna offers much better impedance as well as axial ratio bandwidth, maintains attractive size and shows much better radiation characteristics compared to antennas reported in [30][31][32][33][34][35][36]. Hence, compact size, simple design method, superior impedance, radiation characteristics and wide range circular polarization justifies the good candidature of the suggested lost cost UWB antenna for multiple wireless systems including 5.5 GHz Worldwide Interoperability for Microwave Access (Wi-Max), 5.2/5.8 GHz Wireless local area network (WLAN), X-band satellite communication (downlink: 7.25-7.745 GHz, uplink: 7.9-8.4 GHz), other applications in microwave C, X, Ku bands and UWB communication systems.…”

“…The designs reported in supports broadband/wideband operation, which limits its applications for UWB communication systems. The antenna structures referred in [30][31][32][33][34][35][36] are UWB configurations. The performance comparison table clearly indicates largest operating bandwidth, wide ARBW, good gain and high radiation efficiency of the suggested radiator as compared to other designs proposed in .…”

CPW-Fed UWB-MIMO Antenna with Triple-band Notched and High Isolation using Double Y-shaped Decoupling Structure

“…When MIMO technology is used in antenna design, it can help antennas achieve a high transmission rate and a stable transmission reliability. With MIMO technology, the signal is transmitted in multiple channels, thereby reducing multipath fading and increasing transmission capacity [6]. Many UWB-MIMO antennas are proposed in [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

“…With MIMO technology, the signal is transmitted in multiple channels, thereby reducing multipath fading and increasing transmission capacity [6]. Many UWB-MIMO antennas are proposed in [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. A circularly polarized MIMO antenna is designed in [6].…”

“…Many UWB-MIMO antennas are proposed in [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. A circularly polarized MIMO antenna is designed in [6]. Although the impedance bandwidth is from 3.1-13.5 GHz, the antenna has a narrow axial ratio bandwidth from 4.7-6.1 GHz and is susceptible to be interfered by other useful bands.…”