Four-Port Cylindrical Pattern- and Polarization-Diversity Dielectric Resonator Antenna for MIMO Application

In this communication, a four-port cylindrical pattern-diversity and polarization-diversity dielectric resonator antenna (DRA) for multiple-input multiple-output (MIMO) applications is presented for the first time. The design utilizes two degenerate
$\mathrm {HEM}_{12 \delta + 1 }$
modes and two degenerate
$\mathrm {HEM}_{21 \delta }$
modes of the cylindrical DRA, with unidirectional radiation and quasi-omnidirectional radiation, respectively. The resonant frequencies of four modes can be predicted by the radar cross section characteristic of an isolated DRA. By optimizing the dimension of DRA and loading technology, the
$\mathrm {HEM}_{12 \delta + 1}$
and
$\mathrm {HEM}_{21 \delta }$
modes can operate in the same band. The
$\mathrm {HEM}_{12 \delta + 1}$
modes are effectively excited by two polarization orthogonal slot pairs while two coaxial probes are utilized for exciting the
$\mathrm {HEM}_{21 \delta }$
modes. The power divider with tapered end is presented to expand bandwidth of
$\mathrm {HEM}_{21 \delta }$
modes. In addition, the method based on mode orthogonal to utilize two degenerate
$\mathrm {HEM}_{21 \delta }$
modes with high isolation is proposed. To verify design, a four-port diversity DRA operating at 2.4 GHz band (2.4–2.48 GHz) was simulated, fabricated, and measured. The S parameters and radiation characteristics were measured and discussed. Moreover, the calculated indoor communication performance including the envelop correlation coefficient (ECC), mean effective gain (MEG), and channel capacity as the proposed four-port DRA used for MIMO element are given and discussed.