Triband Omnidirectional Circularly Polarized Dielectric Resonator Antenna with Top-Loaded Alford Loop

Abstract

A triband omnidirectional circularly polarized dielectric resonator antenna with a top-loaded modified Alford loop for GSM, WLAN, and WiMAX applications is proposed. Fed by an axial probe, the DRA (dielectric resonator antenna) radiates like a vertically polarized electric monopole. The top-loaded modified Alford loop provides an equivalent horizontally polarized magnetic dipole mode at triband. Omnidirectional CP (circular polarized) fields can be obtained when the two orthogonally polarized fields are equal in amplitude with phase quadrature. The antenna has been successfully simulated, fabricated, and measured. The experimental and numerical results exhibit that the antenna can obtain usable CP bandwidths of 1.925–1.955 GHz, 2.36–2.48 GHz, and 3.502–3.53 GHz with return loss larger than 10 dB and axial ratio less than 3 dB. In addition, over the three bands, the antenna obtains very good omnidirectional CP radiation patterns in the azimuth plane. Moreover, an average CP gain in the azimuth plane of 1.2, 1.6, and −1.5 dBic for the lower, middle, and upper bands has been obtained.

A state-of-art review on performance improvement of dielectric resonator antennas

“…The literature based on circular polarization has already been discussed in previous section. Apart from this, some other characteristics say wideband, [136][137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152][153] dualband/ multiband [154][155][156][157][158] including circular polarization have also been reported in literature. This is also being discussed in this section.…”

Triple-Band Dual-Sense Circularly Polarized Hybrid Dielectric Resonator Antenna

“…Finally, a performance comparison of the proposed DRA with earlier works [ 12 , 13 , 14 , 15 , 17 , 18 , 19 ] is presented in Table 1 . These structures are compared in terms of −10 dB IBWs, 3 dB ARBWs, and size.…”

“…Compared with [ 14 ], the proposed work has higher gains and compact size. A triple-band omni-directional CP DRA with compact dimensions was presented in [ 19 ]. In comparison, the proposed DRA has wider 3 dB ABBWs and higher gains across all three bands.…”

“…designed a dual-band CP zonal-slot/DRA hybrid antenna where the lower CP comes from the zonal-slot and upper one from the DR [ 18 ], but the size was increased by the use of a rectangular cavity. Although several dual-/wide-band CP DRAs have been proposed, only one triple-band CP DRA with 3 dB ARBWs of 1.55%, 4.96%, and 0.8% is reported [ 19 ].…”

Circularly-Polarized Shaped Pattern Planar Antenna for Aerial Platforms

“…Four feed branches are extended from patch to stimulate horizontally-polarized monopole stubs. The length of curved monopole stubs is optimized to grab desired functional frequency in-correlation to that of the working frequency of the vertically polarized radiator, while gradually narrow outer curved stubs provide better circularly-polarized fields by giving improved phase matching of electric vectors [28].…”