Wideband hybrid circularly polarised rectangular dielectric resonator antenna excited by modified cross‐slot

Abstract

A wideband circularly polarised (CP) rectangular dielectric resonator antenna (DRA) based on the concept of a hybrid antenna is presented. In this design, the modified cross-slot simultaneously performs the functions of an effective radiator and the feeding structure of the rectangular dielectric resonator (DR). By properly designing the structure parameters of the DRA, the resonances of the modified cross-slot and the DR can be merged to obtain a wide CP bandwidth. A prototype antenna is designed, fabricated and measured, and a wide 3 dB axial ratio bandwidth of 24.6% is achieved.Introduction: Dielectric resonator antennas (DRAs) [1] have been investigated extensively in the past two decades because of their attractive features such as low loss, high radiation efficiency, ease of excitation and wide bandwidth. Circularly polarised (CP) DRAs are particularly useful for wireless communication systems because they are less sensitive to the antenna orientation than the linearly polarised ones. The typical 3 dB axial ratio (AR) bandwidth of the regular-shaped DRAs is about 3% [2, 3]. Wider CP bandwidths can be obtained by utilising multiple-feed [4] or novel DRA geometries [5,6]. However, the multiple-feed designs are complicated to implement because they need a complex feeding network. Owing to the existing simple equations for predicting the resonant frequencies of regular-shaped dielectric resonators (DRs), the regular-shaped DRAs are more easy to design than the ones with novel DRA geometries. Several single-point-feed regular-shaped DRAs with a wide CP bandwidth have been reported in recent years. For example, a 3 dB AR bandwidth of 13% has been obtained using concentric open half-loops to excite a rectangular DRA [7]. A lumped resistively loaded monofilar-spiral-slot excited rectangular DRA has achieved a wide 3 dB AR bandwidth of 18.7%; however, the introduction of the resistor in this design leads to a decrease of about 20% in radiation efficiency [8].In this Letter, a wideband CP rectangular DRA is presented based on the concept of a hybrid antenna [9]. The modified cross-slot simultaneously acts as the feeding structure of the rectangular DRA and as a dielectric-loaded modified cross-slot antenna. By optimising the structure parameters of the proposed antenna, the resonances of the modified crossslot excited DRA and the dielectric-loaded modified cross-slot antenna can be merged to achieve a wideband CP operation. A prototype of the proposed antenna has been designed, fabricated and measured. It was found that a 3 dB AR bandwidth as wide as 24.6% can be achieved. Broadside radiation patterns were obtained across all of the 3 dB AR bandwidths.

A Wideband Circularly Polarized Antenna with a Multiple-Circular-Sector Dielectric Resonator

“…It is evident that the proposed antenna exhibits a wider 3 dB AR bandwidth and a higher peak gain compared to the earlier antennas [11,13]. Two antennas [12,14] produced a wider 3 dB AR bandwidths, but their peak gains were lower than that of the proposed antenna. Another antenna [15] employed a trapezoidal DR with overall dimensions of 1.16${\lambda }_0$ × 1.16${\lambda }_0$ × 0.44${\lambda }_0$ (${\lambda }_0$ is the wavelength corresponding to the center frequency of the AR band).…”

“…In order to evaluate the performance of the antenna, a comparison of the proposed antenna and antennas presented in earlier works [11,12,13,14,15] was performed. These results are illustrated in Table 2.…”

“…Compared to LP antennas, CP antennas are more feasible, because they can reduce the losses caused by propagation effects and misalignment between the transmitting and receiving antennas [9]. Thus, the designs of CP DRAs have received much attention recently [10,11,12,13,14,15,16]. The technique for realizing circular polarization through a DRA mostly requires either modifying the excitation mechanism or using a specially-shaped dielectric resonator (DR).…”

“…Zou et al introduced a CP DRA fed by a lumped resistively loaded monofilar-spiral slot, resulting in an AR bandwidth of 18.7% [11]. A modified cross-slot design was also utilized to excite a rectangular DRA to produce circular polarization with an AR bandwidth of 24.6% [12]. Meanwhile, designs of CP DRAs with specially-shaped DRs fed by the aperture-coupled feeding technique were also investigated.…”

Wideband circularly polarized sectored conical dielectric resonator antenna excited by S‐shaped slot

“…Also, a rectangular stair‐shaped dielectric resonator antenna excited by a narrow rectangular slot rotated 45° with respect to sides of the DRA to get CP with 10.6% of 3‐dB AR bandwidth . Furthermore, wideband CP rectangular DR is investigated when excited with a modified cross slot and a 3‐dB AR bandwidth of 24.6% is achieved with the hybrid structure . It is seen that, when a square DR is excited with two unequal slits loaded on diagonal of square, CP mode with 3‐dB AR bandwidth of (43–50) % is achieved .…”