Dielectric resonator antenna

About: Dielectric resonator antenna is a research topic. Over the lifetime, 8199 publications have been published within this topic receiving 111090 citations. The topic is also known as: DRA.

A Circularly Polarized Antenna by Using Rotated-Stair Dielectric Resonator

Abstract: In this letter, a wideband compact circularly polarized (CP) dielectric resonator antenna (DRA) is proposed. This antenna consists of two rectangular dielectric layers that are stacked with a rotation angle $\varphi $ relative to its adjacent bottom layer. The antenna is excited by an aperture coupled through a slot cutting on the ground plane. The rotated-stair configuration of DRA contributes dual broadside CP radiating modes and results in a noticeable enhancement in the axial ratio (AR) bandwidth. The proposed antenna achieves 31% impedance bandwidth and 18.2% AR bandwidth. The average gain within the AR bandwidth is 4.5 dBi with less than 0.5-dB variation. Moreover, the proposed dielectric resonator antenna has a low-profile structure. This work demonstrates a CP bandwidth broadening technique for the DRA. The potential applications of the antenna are 5G Wi-Fi and satellite communication systems.

Design of the Millimeter-wave Rectangular Dielectric Resonator Antenna Using a Higher-Order Mode

Abstract: At millimeter-wave (mm-wave) frequencies, the size of the dielectric resonator antenna (DRA) may be too small to fabricate precisely. To relax the precision problem of fabrication, it is proposed to obtain a larger DRA by designing it with its higher-order mode. In this paper, the rectangular mm-wave slot-fed DRA excited in a higher-order mode is investigated systematically. It is found that when the slot is centrally located beneath the DRA, a TEpqr mode of the DRA can be excited only when all of the indices p, q, r are odd numbers. The aspect ratio of the DRA that gives a single (higher-order) TE11ry -mode operation is found. Like the fundamental TE111 mode, the higher-order TE11r modes have broadside radiation patterns. To validate our results, two DRAs were designed to operate in the higher-order TE115 and TE119 modes. In each case, the reflection coefficient, radiation pattern, and antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The effect of fabrication error on the frequency shift of the DRA was also studied. A design rule for minimizing the frequency shift is suggested. The results should be useful for practical designs of the mm-wave DRA.

Microwave needle dielectric sensors

Abstract: Method and apparatus for in vivo or in vitro sensing of complex dielectric properties of lossy dielectric materials, particularly biological tissue. Configured as a needle-like dielectric sensor, a coaxial cable (1) having a circumferential gap (12) in the shield (2) is wrapped with an electrically thin dielectric substrate (18). The cable center conductor (6) extends immediately past gap (12) and is shorted to cable shield (2). A thin conductive dipole resonator (16) is positioned on substrate (18) and over feed gap (12) to achieve inductive coupling between the cable center conductor (6) and the dipole resonator (16) through gap (12). Superstrate (22), which could be a dielectric catheter, covers the entire sensor assembly (10). By measurement of the resonator resonant frequency and the input impedance matching factor at the resonant frequency, the real and imaginary dielectric components (e', e") of the test material into which the sensor is inserted are determined.

Design of a wideband rasorber with a polarisation-sensitive transparent window

Abstract: The present thesis considers two different subjects in the research area of electromagnetics. The first part is concerned with antenna design and the second with radar absorbers and rasorber.In the first part, a novel excitation technique for cylindrical dielectric resonator antennas is introduced to produce circular polarization. The exciter is a tape helix that is wound around the dielectric resonator and is fed by a coaxial probe. The helix excites the HE11σ modes in phase quadrature in the cylindrical dielectric resonator antenna. The height of the helix is determined using the Hansen-Woodyard condition for an end-fire array based on the phase velocity of the surface wave traveling along the dielectric resonator side wall. This phase velocity is estimated from the phase velocity in an infinitely long dielectric rod with the same permittivity and radius as the dielectric resonator antenna. The helical exciter is required to operate in the helix axial mode. The height of the helix is usually taller than the height of the dielectric resonator core. Using this type of excitation, a 3 dB axial-ratio bandwidth of 6.4% was achieved for a sample design with dielectric constant er ~ 11. The achieved 3 dB axial-ratio bandwidth is greater than that typical of other reported single feed cylindrical dielectric resonator antennas. A prototype of the sample design is fabricated and measured and a good agreement between simulation and measurement is observed. Furthermore, two approaches for the enhancement of the 3 dB axial ratio bandwidth are proposed: removing the central portion of the cylindrical dielectric resonator and using stacked cylinders. The advantages and limitations of each approach are discussed. Another perspective on the proposed design is to consider the antenna as a helix with a dielectric resonator core. In this perspective, the effects of the dielectric core on the helix antenna are discussed.The second part of the thesis is concerned with the design of thin wideband electromagnetic planar absorber for X- and KKu-band which also has a polarization sensitive transparent window at frequencies lower than L-band. The design is based on a two layer capacitive circuit absorber with the backmetal layer replaced with a polarization sensitive frequency selective surface. The structure is studied for normally incident waves with two orthogonal linear polarizations. The structure is optimized to have high transparency at low frequencies for one of the polarizations and at the same time good absorption efficiency for both polarizations at the high-frequency band. For one of the polarizations a -1.9 dB transmission with a transmission loss of less than 10% at 1 GHz as well as a 2.25:1 (75%) bandwidth of -20 dB reflection reduction are achieved. For the other polarization we obtained more than 3:1 (100%) bandwidth of -19 dB absorption. Compared with our earlier design based on a Jaumann absorber, we succeed in significantly reducing the transmission loss at the transparent window. Furthermore, the module of absorption quality is extensively improved. The improvements are based on using periodic arrangements of resistive patches in the structure design. The investigation of the structure for oblique angles of incidence and non-ideal materials is also accomplished.

A hybrid-resonator antenna: experimental results

Abstract: Experimental results are presented for a hybrid-resonator antenna, consisting of a microstrip patch resonator coupled to a dielectric resonator. They demonstrate a 10 dB return-loss bandwidth of 5.14-6.51 GHz (23.5%) and a radiation pattern similar to that of a conventional microstrip patch or dielectric-resonator antenna. The peak cross-polarization level in the upper hemisphere is at least 18 dB below the peak co-polarization level.