Design and Investigation of Orthogonal Hybrid Dual-Mode Single-CDR-Based MIMO Antenna With High Self-Isolation at 5.8GHz

Abstract

In this article, a dual-port single-element coaxial probe-fed cylindrical dielectric resonator MIMO antenna is designed and investigated. The high-permittivity dielectric (<inline-formula> <tex-math notation="LaTeX">${\varepsilon }_{\mathrm {r}}=15$ </tex-math></inline-formula>) is composed of barium-titanate-doped polydimethylsiloxane (PDMS) silicone polymer. The orthogonal excited antenna generates orthogonal modes (<inline-formula> <tex-math notation="LaTeX">$\mathrm {H}\mathrm {E}_{11\delta }^{\mathrm {x}}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\mathrm {H}\mathrm {E}_{11\delta }^{\mathrm {y}}$ </tex-math></inline-formula>) with high port-to-port self-isolation (<inline-formula> <tex-math notation="LaTeX">$\lt -21$ </tex-math></inline-formula> dB) without additional mutual coupling reduction structures. The antenna achieved bandwidths are 5.65&#x2013;5.96 GHz (gain: 8.91 dBi) and 5.62&#x2013;5.92 GHz (gain: 8.97 dBi) for Port1 and Port2, respectively. It has an axial ratio &#x003E;26.5 dB, ensuring orthogonal linear polarization characteristics and improved isolation. The antenna attains excellent MIMO parameters; TARC <inline-formula> <tex-math notation="LaTeX">$\lt -10$ </tex-math></inline-formula> dB, VSWR-MIMO &#x003C;2, ECC &#x003C;0.24, DG <inline-formula> <tex-math notation="LaTeX">$\sim ~10$ </tex-math></inline-formula> dB, CCL &#x003C;0.4 bits/sec/Hz, and MEG <inline-formula> <tex-math notation="LaTeX">$\lt \pm 3$ </tex-math></inline-formula> dB in operating bandwidth. The HFSS simulated and investigated performance parameters of the MIMO antenna are found to be in excellent agreement with experimental data, this validates the antenna&#x2019;s MIMO functionality. The antenna is modeled as a parallel RLC equivalent circuit in ADS using a novel technique based on complex-valued impedance parameters (Zij). This approach demonstrates improved accuracy, validated by both simulations and measurements. The antenna is suitable for ISM (5.725&#x2013;5.85 GHz), WLAN 5.8 GHz, C-band (5.0&#x2013;6.0 GHz).