Planar Dielectric Resonator Research Articles

A Self-Decoupling Method for MIMO Linear and Planar Dielectric Resonator Antenna Arrays Based on Transmission Characteristics of Feeding Structure

In this paper, a novel self-decoupling method for the multi-input multi-output (MIMO) dielectric resonator antenna (DRA) arrays is investigated. This method is based on the transmission characteristics of the conformal strip that feeds the DRA. It is found that when the strip-fed DRA operates in the higher-order mode, e.g., TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">113</sub> mode, the E-field coupled to the metal strip of the adjacent passive DRA presents a standing wave distribution. By appropriately adjusting the dimensions of the feeding strip, the E-field can form a node with zero amplitude at its bottom where a coaxial probe is connected, preventing the energy from getting into the receiving port and hence achieving a high isolation level without requiring any extra decoupling structure. This self-decoupling method is applicable not only to one-dimensional (1-D) H- and E-plane coupled MIMO linear arrays but also to two-dimensional (2-D) MIMO planar array. To verify its feasibility, a prototype of 2 × 2 MIMO planar DRA array is simulated, processed, and tested. The results show that a usable bandwidth (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ii</sub> | < -10 dB and |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ij</sub> | < -20 dB) of 10.8% is achieved, and the maximum isolation is over 40 dB within the passband.

Increasing the Q-factor of thin planar dielectric resonator with whispering gallery modes

AbstractThe spectral and energy characteristics of the tunable thin planar dielectric resonator with the movable metal mirror are researched. It is found that the high-Q HE-polarized whispering gallery modes (WGMs) are effectively excited in such a resonator by the dielectric waveguide. A mode set of the tunable thin planar dielectric resonator depends on the presence of an air gap in its design. Changing the height of the air gap affects the energy characteristics of the tunable thin planar dielectric resonators (DR). Shifting the resonant fields of WGMs from the dielectric disk to the air gap is the reason for this effect. It is shown that at certain heights of the air gap, increasing the unloaded Q-factor of the tunable thin planar DR and improving the excitation efficiency of WGMs in it is achieved.

Circularly Polarized SIW DRA Fed by Ridge Gap Waveguide for 60 GHz Communications

A compact planar dielectric resonator antenna (DRA) is designed based on the substrate integrated waveguide (SIW) technology for 60 GHz communications. The proposed antenna is constructed from a multilayered dielectric substrate separated by metallic sheets. A dog-bone shaped DRA is formed by perforating the upper dielectric substrate with air holes surrounding the dog-bone structure. The DRA is surrounded by metallic vies connecting two metal sheets above and below the substrate containing the DRA. The DRA is fed through a slot coupled microstrip transmission line printed below the slot. The ridge-gap waveguide technology (RGW) is used in the feeding layer to suppress the surface wave surrounding the microstrip transmission line and improve the peak gain. The RGW unit-cell structure has stop-band of 46–95 GHz. The SIW DRA introduces impedance bandwidth from 59.4 to 60.4 GHz (1.67% referenced to 60 GHz) with peak gain of 6.78 dBi. The circular polarization (CP) is achieved by the rotation of the dog-bone shaped DRA by 45° with respect to the feeding slot. It produces left-hand CP with a bandwidth of 0.22 GHz (0.36%). A 2 × 1 SIW-DRA elements are designed with sequential rotation and phases for CP bandwidth enhancement. The peak gain increases to 9.1 dBi, and a broadband AR of 4.8 GHz (8%) is achieved. 2 × 2 SIW-DRA elements with 90° orientation rotation angle and phases of 0, 90°, 180°, and 270° are designed. An improvement in the peak gain of 11 dBi is produced with wide AR bandwidth of 10.8 GHz (18% from 54.2 GHz to 65 GHz) for 60 GHz communications.

A shielded planar dielectric resonator with whispering gallery modes

The spectral and energy characteristics of two planar dielectric resonators (DRs), open and shielded from the curvilinear surface, excited in higher-order modes as whispering gallery modes (WGMs) in Ka-waveband are investigated. These resonators are formed by a thin (compared to the operating wavelength) disk dielectric structure, located between two conducting planes. Thus, the E-field of the resonator was limited along the height of the planar disk by two conducting surfaces. The resonance properties of such a structure are determined by the condition of total internal reflection of waves from the internal curvilinear surface of a dielectric disk. The carried out investigations shown that the unloaded Q-factor is increased at the arrangement of planar dielectric disk inside the ring metal shield at the certain ratio of the radiuses of the shield and dielectric disk. The Q-factor of the shielded resonant structure at the high-frequency edge increases to 40 %. The partial displacement of the resonant field of the WGMs modes from the dielectric to the air gap is the cause of this effect. It leads to decrease in losses in the dielectric material. A computer simulation of the WGMs fields in the planar DR was carried out using the CST Microwave Studio 2013 software to confirm this effect. In addition, computer simulation results shown that these WGMs in the planar DR are characterized by a homogeneous distribution of the resonant field along the axial coordinate. The perspectives of using planar DR in solid-state Ka-band oscillators are shown.

Increasing Q-Factor of Planar Dielectric Resonators with Whisper Gallery Modes

Planar dielectric resonators (DR) with height significantly lower than the operating wavelength are investigated as a new class of disk dielectric resonators of the millimeter wavelength range with whispering gallery (WG) modes. It is known that in the open state, such resonators based on the WG modes are not excited due to high radiation losses. It is shown that the solution of this problem is the partial shielding of the disk dielectric structures with a plane-parallel screen by placing the disk between two flat conducting mirrors. It has been established that by introducing an air gap between the flat base of the dielectric disk and one of the conductive mirrors, it is possible to increase the quality factor of the planar DR almost twice. One of the reasons for this is the partial displacement of the resonant field of the WG modes from the dielectric region to the air gap, where the dielectric losses are lower. In addition, an increase in the air gap in the range of optimal values, comparable to half the working wavelength, leads to a decrease in ohmic losses. The above causes an increase in the quality factor of planar DR as an air gap is extended.

Rectangular ring‐shaped dielectric resonator antenna for dual and wideband frequency

AbstractA new modified planar dielectric resonator antenna (DRA) is presented and investigated. The proposed DRA is excited by a microstrip feed that is extended as a probe in the proximity of the DR. On the opposite side to the probe excitation printed narrow strips directly connected to the ground plane edge are used to improve the radiation characteristics of the antenna by keeping a unidirectional broadside radiation. In addition, the short circuit strips introduce a second frequency band. Thus, a dual‐band antenna is achieved. The measured bandwidths are about 73% (2.78–5.95 GHz) for the wideband DRA as well as 8% (2.4–2.6 GHz) and 56% (3.3–5.85 GHz) for the dual‐band DRA. The minimum and maximum gain enhancements of about 0.6 and 1.2 dB from 3.5 to 6 GHz are obtained. Parametric study and measurement results are presented and discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1077–1081, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27492

Novel Microwave Gas Sensor using Dielectric Resonator With SnO2 Sensitive Layer

A new generation of passive gas sensors that works at millimeter-wave frequency (50 to 70 GHz) incorporating sensitive material is presented. The sensor uses a microwave planar dielectric resonator operating with whispering gallery-modes. The dielectric resonator (DR) is covered by SnO2 thin film as sensitive layer. A gas adsorption makes the SnO2 effective dielectric parameters changing namely its permittivity. Such changing modifies the resonance frequency of the resonator. Here, the proof of concept is demonstrated thorough full wave simulations. This sensor is a passive circuit and has great potential for wireless sensing network applications.

Synchronization of wakefield modes in the dielectric resonator

Multimode excitation of a wakefield in a planar dielectric resonator by a regular sequence of relativistic electron bunches is studied analytically and numerically. It is shown that, if the wakefield being excited consists of a large number of radial modes, the fields from the regular sequence of the bunches add together. Conditions under which this sequence provides synchronization of the dielectric resonator modes are found. Acceleration of a test bunch in the wakefield of the bunch sequence is studied.

VCO/RADIATOR MODULE TUNED BY FERROELECTRIC VARACTOR

ABSTRACT Design of tunable Gunn diode—based active antenna module including a new type of planar dielectric resonator (PDR) tuned by a ferroelectric (FE) varactor is presented. The module is designed in such a way that the PDR acts both as a stabilizing resonator and as a radiator. MW properties of FE elements used for VCO tuning are considered. The module operates at frequency around of 17 GHz and demonstrates the radiated power of 8.8 ± 0.1 dBm over the 130 MHz tuning range and a phase-noise level of −95 dBc/Hz at 100 kHz offset. 65° width of the radiation pattern in both the E and H planes corresponding to a gain of 5.1 dBi was measured. The maximal VCO power limited by the dielectric nonlinearity of a FE film in the microwave electric field and by the FE film overheating is estimated for FE film-based varactors of the planar and parallel structures.

Active Integrated Antenna Based on Planar Dielectric Resonator With Tuning Ferroelectric Varactor

Design of tunable Gunn diode-based active antenna module including a new type of planar dielectric resonator (PDR) tuned by a ferroelectric (FE) varactor is presented. The module is designed in such a way that the PDR acts both as a stabilizing resonator and as a radiator. Microwave properties of FE elements used for voltage-controlled oscillator (VCO) tuning are considered. The module operates at a frequency around of 17 GHz and demonstrates the radiated power of 8.8plusmn0.1 dBm over the 130-MHz tuning range and a phase-noise level of -80 dBc/Hz at 100-kHz offset. 65deg width of the radiation pattern in both the E-and H-planes corresponding to a gain of 5.1 dBi was measured. The VCO module has been tested in the regime of the frequency modulation. The output signal spectra measured and simulated for modulating bipolar voltage pulses of repetition frequency f=2 MHz are presented.

High‐Frequency Electromagnetic Bandgap Structures via Indirect Solid Freeform Fabrication

The indirect solid freeform fabrication process is used to fabricate low‐loss complex geometry periodic dielectrics for use in the microwave range. Relevant processing details, such as mold fabrication, slurry rheology, curing, and binder burnout, are discussed. Woodpile electromagnetic bandgap structures exhibiting a −40 dB well were shown to be operational at frequencies &gt;110 GHz. Novel designs of planar periodic dielectric resonators with Q= 965 at 33 GHz (Q= ratio of the power stored to power lost in the resonator) were realized in alumina. Metallo‐dielectric filters with low‐insertion loss were also created via ISFF; modeling of these structures using resistor‐inductor‐capacitor‐equivalent circuit analysis was performed to calculate a Q of 645.

Mixed modes cylindrical planar dielectric resonator filters with rectangular enclosure

A compact mixed modes cylindrical planar dielectric resonator filter in a rectangular enclosure is presented. Space coupling between the resonators excited in different modes and iris coupling between the identical resonators are realized in the filter. All the couplings and resonant frequencies of the DR cavities are computed by a rigorous full wave mode matching method and a cascading procedure using generalized scattering matrices. A 6-pole elliptic function filter is designed and constructed, and the measured filter frequency responses verify the theory.

New experimental results of millimetre-wave whispering gallery mode dielectric resonators excited by microstrip lines

The letter presents an experimental investigation of planar millimetre-wave dielectric resonators acting on whispering gallery modes and excited by microstrip lines. Experimental results including measured resonant frequencies and loaded quality factors obtained in both Ka bands (26.5–40 GHz and 90–100 GHz) will be presented.