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Dielectric Resonator-Based Multiple-Input Multiple-Output (MIMO) Antennas
Published in Binod Kumar Kanaujia, Surendra Kumar Gupta, Jugul Kishor, Deepak Gangwar, Printed Antennas, 2020
Gourab Das, Ravi Kumar Gangwar
A dielectric resonator antenna (DRA) is a ceramic-based resonator that is able to radiate electromagnetic (EM) energy into space after proper excitation [24]. In the past, the ceramic resonators were used in filter and oscillator circuits; thus, it can offer a substitute to the waveguide cavity resonator. To prevent radiation, these ceramic resonators were bounded in a metallic cavity (for filter and oscillator applications). These ceramic resonators have a high quality (Q)-factor (20–50,000) and better temperature stability [25]. The history of dielectric resonators is very interesting, from circuit applications to antenna applications. In 1939, Richtinger was the first person who theoretically developed the dielectric resonator in the form of an un-metalized dielectric [26]. After that, in 1960s, two US-based scientists, Okaya and Barash examined the excitation of modal pattern in the dielectric resonators [27]. But still, the dielectric resonators are used for circuit applications rather than as an antenna element. In 1980s, S.A. Long and his research group examined the ceramic-based resonator as an antenna. After removing the metallic shielding and lowering the dielectric constant, the resonant modes and radiation characteristics were investigated [28]. In this way, they proved that the dielectric resonator can act as a radiator.
Horn DRA Antenna
Published in Rajveer S. Yaduvanshi, Gaurav Varshney, Nano Dielectric Resonator Antennas for 5G Applications, 2020
Rajveer S. Yaduvanshi, Gaurav Varshney
The dielectric resonator material used in resonant antennas was proposed in 1983. Due to minimized metallic loss, the dielectric resonator antenna (DRA) is efficient particularly as compared to metallic antennas if operated at millimeter wave and terahertz frequency spectrums. High dielectric constant material can further reduce the size of the DRA. Hence, it is a small and low profile antenna. Low cost dielectric materials are now easily available commercially. The horn antenna is a type of aperture antenna. The radiation fields from aperture antenna can be determined from fields over the aperture. The aperture fields become the sources of the radiated fields at far fields, and the frequency spectrum is classified as LF, HF, VHF, UHF, SHF, L, S, C, X, Ku, K, Ka, mm wave, THz, etc. There are different types of DRAs, such as E-plane, H-plane, and EH or pyramidal horn. The horn antenna is designed by flaring a hollow rectangular cross section to a larger opening. Horn antennas are easy to excite for providing high gain and have a wide impedance-bandwidth, implying that the input impedance is fairly constant over a wide frequency range. A long horn with small flare angle is required to obtain uniform aperture fields distribution. Both fundamental and higher order modes have been obtained. Mode merging can provide large bandwidth, and mode shifting can result in multi bands. Higher order modes can result in higher gain [1–11].
D
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
difference-mode signal (2) ratio of the electrical capacity of a condenser, which has a given material as the dielectric, to the capacity of an identical condenser, but with air as the dielectric. (3) permittivity of a medium normalized to the permittivity of free space; a measure of the response of a dielectric to an applied electric field. (4) an electric property of an insulator or semiconducting material, which describes how differently electric fields will behave inside of the material as compared to air. As an example, er = 12.9 for GaAs as compared to er = 1 for air. In integrated circuits, an effective dielectric constant (eeff ) is used, since the electric fields supported by the signals traveling through the conductors on the circuit flow through both air and the insulator or semiconductor simultaneously. dielectric discontinuity interface between two media with different dielectric permittivity properties. dielectric medium medium that is polarizable but relatively nonconducting. dielectric resonator an unmetallized dielectric object of high dielectric constant and high quality factor that can function as an energy storage device. dielectric resonator antenna (DRA) an antenna where a dielectric resonator is used as the radiation element. dielectric resonator [stabled] oscillator (DRO) a dielectric resonator is a cylindrically shaped piece of material, or "puck," that has the properties of having low-loss resonant frequencies that are determined primarily by the size of the cylinder. Placing a dielectric resonator near a microstrip line can form a resonant circuit that will frequency stabilize a voltage-controlled oscillator. dielectric slug tuner system of two movable dielectric pieces of material placed on a transmission line for the purpose of matching a wide range of load impedances by means of placing the dielectrics in proper positions. dielectric step discontinuity the junction between different dielectric waveguides. dielectric waveguide a waveguide that relies on differences in permittivity among two or more materials to guide electromagnetic energy without the need for ground planes or metallic strips. Such guides of rectangular, circular, elliptical, and other cross sections are made of dielectric materials and used for transmitting signals. Transmission is accomplished by the total internal reflection mechanism inside the waveguide. difference amplifier See differential amplifier.
A Wideband Single-fed circularly polarized dielectric resonator antenna with bandpass filtering response
Published in Electromagnetics, 2022
Wei Luo, Yulu Feng, Yi Ren, Min Wang
With the application of massive multiple-input multiple-output (MIMO) technology in 5 G mobile communication systems, the number of antennas and radio frequency (RF) devices has doubled, and the limited installation space puts higher requirements on the miniaturization and integration of RF front ends. In previous designs, filters and antennas are two indispensable devices that are separately designed and then cascade into the RF system. This methodology results in a bulky RF front-end system, a heavy weight, a complex structure, and a high insertion loss. To solve these problems, filtering antennas have attracted attention in recent years (Liu et al. 2019; Xiang et al. 2021; Xie, Chen, and Qian 2020). Filtering antennas refer to the design, simulation and optimization of the antenna and filter circuit at the same time, which avoids the impedance mismatch problem and reduces the size of the circuit to a certain extent. Filtering antennas have the advantages of low loss, high selectivity, wide harmonic suppression band, and so on (Ranjan and Kumar 2021; Rao et al. 2022). A dielectric resonator antenna (DRA) is a kind of resonator antenna composed of nonmetallic dielectric materials, which generates radiation from a polarized current with features of high design freedom, low loss, and easy coupling (Tang, Tong, and Chen 2019; Yang and Leung 2020; Yang et al. 2020). The inherent resonant characteristics and three-dimensional structure of a DRA make it a promising antenna candidate for the design of a filtering antenna.
Conductor Backed CPW-Fed Dual-Mode Excited High Gain Cylindrical Cavity DRA for Unmanned Aircraft Systems (UAS) or Drone Data-Link Applications at C Band
Published in IETE Technical Review, 2019
Pramod Kumar, Santanu Dwari, Shailendra Singh, Jitendra Kumar, Amitesh Kumar
In recent years, rapid progress in modern wireless communication has led to the invention of different types of antennas. Dielectric resonator antennas are introduced as a possible replacement for metallic antennas, because it has attractive features like smaller size, zero conductor loss, the low-temperature coefficient of frequency, high efficiency, wide bandwidth, efficient coupling with transmission line [6,7]. By using different feeding techniques, dielectric resonator antenna (DRA) of the same size and shape can be excited for different modes that generate different radiation pattern and polarization. The most common methods of feeding are probe/coaxial feed; microstrip feed, aperture-coupled feed and coplanar waveguide (CPW) feed [7–10]. Due to the less dispersive nature of CPW line, it has emerged as an alternative to microstrip feed for DRA. In addition, the uni-planar nature of CPW offers several advantages over the conventional microstrip line. It simplifies fabrication, and facilitates easy shunt as well as series surface mounting of active and passive devices with reduced radiation losses [11–16]. In spite of all these advantages, still, a very limited work is available on conductor backed (CB)-CPW DRA [17,18].
Rectangular DR-based dual-band CP-MIMO antenna with inverted Z-shaped slot
Published in International Journal of Electronics, 2020
Planar structures are preferably designed for MIMO antennas. Some are studied in literature (Jehangir & Sharawi, 2016; Liao, Hsieh, & Dai, 2015; Sharawi, Numan, Khan, & Aloi, 2012). However, these metallic reflector-based antennas suffer with low efficiency (less than 70%) and large planar geometry. In contrast, dielectric resonator antenna (DRA) offers high gain, radiation efficiency, low surface waves and versatility in design as well as in feed structures (Mongia & Bharti, 1994; Petosa, 2007). Several DRA-based MIMO antennas have been proposed by researchers with different isolation enhancement techniques including defected ground structure, adding parasitic strips, orthogonal feed and use of power divider circuits. Two cylindrical DRAs with defected ground are designed in Guha, Biswas, Joseph, & Sebastian (2008). Circular ring around the DRA is etched in the ground plane to enhance isolation. In Abdalrazik, Hameed, & Rahman (2017), three orthogonally decoupled modes are excited in rectangular dielectric to reduce envelope correlation coefficient (ECC). A compact four-port cylindrical DRA for cognitive radio applications is presented. Both ultrawideband and narrowband antennas are integrated on a compact surface with high isolation (Pahadsingh & Sahu, 2018). In Sharawi, Symon, Khan, & Antar (2017), four DRA elements are placed at 45° rotation to each other and a central metallic plate is used to enhance isolation. Rectangular Dielectric Resonator Antenna (RDRA) with two different feeds CPW and coaxial probe to excite two orthogonal modes and , respectively, is designed in Roslan, Kamarudin, Khalily, & Jamaluddin (2014). Shorting pins and metallic strips are used to tune the desired band which makes the fabrication process complex. In Khan et al. (2017), dual-band MIMO with stacked dielectric is designed for WiMAX and WLAN applications. Two dielectrics with different permittivity are stacked to enhance radiation efficiency. In Das, Sharma, & Gangwar (2017), authors have presented a single radiator aperture couple Cylindrical Dielectric Resonator Antenna (CDRA)-based MIMO antenna. Orthogonal modes are excited by using power divider to enhance isolation. In Sharma, Das, & Gangwar (2016), authors designed a CDRA-based dual-polarised antenna by etching circular slot with orthogonal L-shaped slit in ground plane.