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In this study, a compact reconfigurable dielectric resonator antenna (DRA) array is proposed to operate in the band IEEE 802.11 WLAN. The main goal of this design is to propose an array feeding topology to avoid radiated beam squinting due to frequency alteration and acquire some gain enhancement with miniaturized array size. For that, the parallel–series geometry is used to layout a microstrip feeder with four output ports on the front plane. Each output port coupled with a rectangular slot (RS) at the bottom plane, and a rectangular dielectric resonator (RDR) mounted above the RS. The frequency reconfigurability is attained by employing PIN diodes that are integrated with the four output ports to operate as switches. Moreover, an impedance equivalent circuit model of the proposed array is postulated for studying the resonance behavior to ensure the validity of the proposed design prior to simulation and fabrication. The prototype 64 × 18 mm2 achieves frequency agility in the range of 5.8 to 5.17 GHz. Also, the realized gain ranges from 12.2 to 10. 5 dBi. The array specifications make it a decent potential candidate to be used for WLAN wireless systems. [ABSTRACT FROM AUTHOR]

This paper inspects a parasitic element‐based inverted meandered U‐shaped printed line fed hybrid MIMO DRA. The feed of a single element of the 2‐elements hybrid MIMO DRA consists of a meandered shaped line coupled to the inverted L‐shaped parasitic element printed on the top side of FR‐4 substrate with a partial ground on the back. The rectangular‐shaped alumina dielectric is placed over the feed to form the single element hybrid DRA. The individual element resonating at 3.40–4.32 GHz (23.83%) and 4.96–5.05 GHz (1.80%) achieves the dual‐band characteristics by exciting multiple modes within the rectangular dielectric resonator. The low‐profile Multiple Input–Multiple Output (MIMO) antenna configuration having an overall size of 0.57 λ × 0.23 λ × 0.14 λ mm3consists of two orthogonally placed hybrid rectangular DRAs. The inter‐element isolation for a connected ground MIMO structure is better than 22 dB in the desired bands of operation without using any isolation improvement techniques. The MIMO diversity parameters are simulated and measured to validate the MIMO performance. The diversity metrics envelope correlation coefficient is below.175, and.15, the mean effective gain ratio is 0 dB, the total active reflection coefficient values are below 15 dB, and channel capacity loss values are below 0.5 bits/sec/Hz in the lower, and upper bands of operation which are within the recommended practical limits. The presented MIMO design achieved the peak gain of 12.87dBi, and minimum radiation efficiency of 83%, with stable radiation characteristics that make the antenna suitable for Sub‐6 GHz 5G and WiFi‐6 applications. [ABSTRACT FROM AUTHOR]

This work presents a dual‐element multiple‐input‐multiple‐output (MIMO) dielectric resonator antenna (DRA) for sub‐6 GHz applications. The proposed MIMO‐DRA has two major features: (i) circular polarization (CP); and (ii) high interport isolation. The proposed MIMO‐DRA is formed by two identical antenna elements. Each element is composed of a cylindrical dielectric resonator (DR) which is fed by a microstrip line via the underneath octagonal aperture. A modified L‐shaped strip along with the octagonal aperture delivers the desired CP characteristics. Meanwhile, a novel defected ground geometry (DGG) is utilized to enhance the inter‐port isolation across the operating frequency bandwidth. The proposed MIMO‐DRA has an inter‐port isolation of greater than 21 dB over the operating 10‐dB impedance band of 4.18–6.12 GHz. Furthermore, the proposed MIMO‐DRA features broadside radiation patterns, satisfactory broadside gains, and well‐acceptable values of envelope correlation coefficients (ECCs). [ABSTRACT FROM AUTHOR]

A dual‐mode dielectric resonator based on printed circuit board (PCB) technology formed bandpass filter is proposed for relatively wide bandwidth under low quality factor. By using the low dielectric constant substrate itself to become the core part of the two coupled dual‐mode resonators through the PCB process, the proposed design can share the same substrate with other PCB circuits and reduce the installation error. Moreover, benefiting from the dual‐mode (TE111y mode and TM111z mode) resonator realized by low dielectric constant substrate with low quality factor, the proposed design exhibits the features of low cost and wide bandwidth. A prototype with the center frequency (f0) of 13.85 GHz was demonstrated, which shows the 3‐dB fractional bandwidth of 8.34% and the minimum insertion loss of 1.29 dB. [ABSTRACT FROM AUTHOR]

A novel filtering dielectric resonator (DR) antenna (DRA) is designed in this article. By using a single‐layer planar feed structure, the TM01δ and TM011+δ modes of a cylindrical DR are excited. The proposed filtering DRA achieves a good omnidirectional radiation performance and a flat gain response. By loading a crossed patch with four shorting pins on the feed structure, the lower edge of the passband obtains a steep roll‐off rate. By plating four metal patches on the side wall of the DR, a radiation null (RN) is successfully introduced at the upper sideband of the DRA. The suppression levels of the proposed filtering DRA in the lower and upper stopbands are above 18 dB. Therefore, the proposed filtering DRA achieves filtering function without additional circuits. For demonstration, a prototype DRA is fabricated and measured. The simulated and measured results are basically consistent. [ABSTRACT FROM AUTHOR]

A hybrid dielectric resonator antenna (HDRA) with a single‐probe generating circular polarization (CP) simultaneously at X and Ku‐bands is presented in this article. A novel hybrid structure of semi‐circular patch and semi‐cylindrical dielectric resonator (DR) of equal radius are combined with a single‐point probe feed to achieve dual‐functional wide CP bands. The asymmetric nature of the semi‐circle and semi‐cylinder produces two orthogonal modes in their respective bands for CP radiation. The measured impedance bandwidth obtained by the proposed structure is 36.49% (3750 MHz) at X‐band and 14.23% (2100 MHz) at the Ku‐band range of frequencies. Axial ratio (AR) bandwidth of 30.39% (3100 MHz) is obtained at X‐band and 13.24% (1950 MHz) at Ku‐band. The measured gains are 9.54 dBic at 9.6 GHz and 6.55 dBic at 15 GHz. An excellent agreement between the computed and measured results validates the design of the dual functional circularly polarized HDRA. [ABSTRACT FROM AUTHOR]

A broadband microwave absorber based on fractal rectangular dielectric resonator (DR) unit is investigated in this paper. The designed absorber can be fabricated with low‐cost three‐dimensional printing technology, using the high‐loss carbon‐carrying acrylonitrile‐butadiene‐styrene (ABS) polymer. To enhance the operating bandwidth, the fractal‐shaped rectangular DR unit is used and multi modes are excited. For verify, a prototype of the absorber with 8 × 8 unit cells were fabricated and measured. The results indicate that the absorptivity can achieve greater than 90% within a relative bandwidth of 130% from 3.1 to 14.7 GHz, which covers the whole C‐band (4–8 GHz) and X‐band (8–12 GHz). In addition, the absorption properties of the absorber at different incident angles were studied. [ABSTRACT FROM AUTHOR]

In this article, Dual port excitation spiral shaped dielectric resonator multiple input multiple output (MIMO) antenna is explored for wideband application. Dual coaxial feeding in inner and outer edge of spiral geometry generates orthogonal hybrid modes. Merging of various hybrid modes lead to a wide bandwidth of operation. HE11δx, HE11δy and HE12δx, HE12δy orthogonal radiating modes are investigated at 8.7 GHz and 11 GHz resonant frequencies, respectively. Proposed antenna covers wide operating frequency range from 8–15.1 GHz to 7.8–14.6 GHz corresponding to excitation of Port‐1 and Port‐2, respectively, is achieved between ports. Isolation below −25 dB. Envelope correlation coefficient, diversity gain, Total active reflection coefficient, radiation pattern, channel capacity loss, gain, efficiency and various other characteristics of MIMO antenna are explored. This antenna can be used for various C and X band wireless applications. [ABSTRACT FROM AUTHOR]

An effective method for reducing the mutual coupling between wideband dielectric resonator (DR) antennas (DRAs) is proposed by covering the metal on the middle dielectric bridge, the contralateral sides and contralateral upper edges of the DRs. This metal decoupling structure can make the coupled electric fields in the adjacent DR be perpendicular to the electric fields of the excited DR, which produce wideband and high isolation between two adjacent DRAs. Thus, the gain of DRA can be restored. For the structural characteristics, the dielectric bridges can connect the decoupling structure and the dielectric blocks of DRAs with high dielectric constant together on the same substrate by PCB process. Finally, the isolation level of the proposed DRAs can be enhanced from 15.5 to 32.3 dB over the effective frequency range from 10.22 to 13.37 GHz or 26.7%. [ABSTRACT FROM AUTHOR]

In this paper, a wideband circularly polarized two‐layer concentric cylindrical dielectric resonator antenna (CDRA) is proposed for C‐band applications. To generate the circular polarization in the CDRA, the proposed antenna is excited with four turn helical wire. The helix excites the two orthogonal modes (HE11δ) in quadrature phase, which result in the circular polarization. The four different design cases are investigated and the best one is fabricated and measured. The impedance bandwidth is improved when two‐layer concentric CDRA is used. The simulated and measured bandwidth of the proposed antenna varies from 3.60 to 6.03 GHz with impedance bandwidth of 50.46% and 3.65 to 6 GHz (48.70% impedance bandwidth) respectively, while axial ratio impedance bandwidth are 43.13% (4.20–6.51 GHz) and 38.82% (4.40–6.52 GHz) respectively. The proposed antenna attains 10.9 dBi measured peak gain at 4.5 GHz. The fabricated prototype is experimentally measured and its results are found to be in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

A low‐loss filtering switch by using the dielectric waveguide resonators (DWRs) is proposed. It is composed of a dielectric part and a printed circuit board (PCB) part, which are electrically connected by soldering. The filtering function is mainly implemented by the coupled DWRs and the switching function is realized on the PCB by simply changing the resonant frequency of the DWR. A fourth‐order filtering switch, in which two DWRs are designed to be switchable, is designed for verification. When the PIN diodes are turned off, the filtering switch is on and an excellent bandpass response is obtained. No extra loss is caused by the off‐state PIN diodes. When the PIN diodes are turned on, the resonant frequencies of the two switchable DWRs are moved away so that the filtering switch is off. Then, the designed filtering switch is fabricated and measured. The simulated and measured results exhibit excellent accordance. In on‐state measurement, the passband is from 3.5 to 3.6 GHz and the in‐band insertion loss is as low as 0.8 dB. Nevertheless, the proposed design owns much lighter weight since no metal cavity is used. In the off‐state measurement, the isolation is better than 36 dB. [ABSTRACT FROM AUTHOR]

This article demonstrates a new type of annular ring shaped cylindrical dielectric resonator (ARCDR) loaded printed ultra‐wideband (UWB) antenna which is further loaded with a new type of two‐layer UWB frequency selective surface (FSS) structure. The proposed FSS helps to improve the peak gain of the standalone hybrid antenna significantly (about 4.45 dB). The proposed FSS loaded hybrid antenna provides measured impedance bandwidth (IBW) and measured peak gain about 115.5% (S11 ≤ −10 dB, 3.75 to 14 GHz) and 10.3 dBi respectively. The top layer of FSS structure employs a square loop configuration integrated with "+" sign, staged in 45° angle. Bottom layer of FSS consists of a square loop. The standalone proposed FSS structure also provides large transmission (S21 ≤ −10 dB, 108%, measured) bandwidth (BW) from 3.5 to 11.75 GHz. The behavior of the proposed UWB antenna geometry has been studied in both frequency and time domains. The newly proposed FSS structure and integrated antenna have been fabricated and there is a close agreement between the simulated and the measured performances. [ABSTRACT FROM AUTHOR]

A differential‐fed dual‐polarized dielectric patch (DP) antenna with high gain, wide bandwidth, and high isolation is investigated in this article. Based on the analysis of the anisotropic property of the DP antenna, further exploration of gain enhancement is carried out. The introduction of the square air hole in the substrate to obtain a hollow DP resonator is a crucial technique. It not only increases the electromagnetic radiation from the sidewalls of the DP resonator to further improve the gain to 8.9 dBi, but also shifts the dominant TM101 mode upward to get close to the higher‐order TM121 mode to achieve bandwidth expansion of 19.4%. By using the differential‐fed scheme to excite the TM101 mode, TM121 mode and their degenerate modes, dual‐polarization operation and high isolation level can be obtained simultaneously. [ABSTRACT FROM AUTHOR]

A novel metamaterial inspired small array Fabry‐Perot Resonator cavity antenna is designed over a wide‐band dielectric resonator antenna to enhance gain and bandwidth operating at C‐band applications. Further, the cavity resonator is modified with the application of 12 no. of RF p‐i‐n diodes between the upper layer of the posterior unit‐cells to achieve the polarization reconfigurability (PR) keeping the bandwidth, gain and efficiency intact. The overall dimension of the proposed antenna is 0.8 λ × 0.8 λ × 0.56 λ. With the PR architecture, the antenna imparts 4.8 GHz bandwidth operating between 4 and 8.8 GHz with an average simulated efficiency of 72% and an average gain of 20 dBi throughout the operating band. The specific alignment of the diode polarity enables the model to obtain left‐handed circular polarization and/or right‐handed circular polarization. [ABSTRACT FROM AUTHOR]

A ferrite‐loaded four‐petal‐shaped antenna with enhanced bandwidth is designed and fabricated. There are two layers in the antenna. A substrate integrated waveguide cavity is formed by a circular metallized via array on the lower substrate of the antenna. As a broadband radiating element, a four‐petal‐shaped radiation unit is etched on the bottom surface of the circular SIW cavity. By loading low‐loss ferrite discs with relatively high dielectric constant in the upper substrate layer as dielectric resonators, a relatively smaller broadband cross‐dipole antenna is realized. The measured results demonstrate that the working frequency band of the antenna is 1.83 to 3.53 GHz (63.4%) if the S11 is less than ‐10 dB. The antenna with the size of 0.29λmax × 0.29λmax has stable bidirectional radiation patterns with the average realized gain and radiation efficiency of 4.14 dBi and 94% in the working frequency range. Due to the characteristics of low cost, low profile, easy integration with planar circuit, the proposed antenna is suitable for wireless communication applications, such as CDMA, 4G, 5G, IMT‐2000, WiMAX, WiFi, and Bluetooth. [ABSTRACT FROM AUTHOR]

A broadband circularly polarized dielectric resonator antenna (CP DRA) with L‐shaped dielectric resonator strips (DRS) is presented. The antenna is composed of a square DR, four L‐shaped DRS and a square ground plane etched with cross‐slot. A stepped‐microstrip feeding line is used to adjust the impedance bandwidth (IBW). It is noted that not only the interaction of the cross‐slot and square DR could excite CP resonant points, but the four L‐shaped DRS can also stimulate a CP resonant point in high frequency. Through utilizing these resonant modes, the CP bandwidth of the proposed DRA could be enhanced greatly. The measured results depict the designed DRA has a broad −10‐dB IBW of 44.7% (2.55, 1.98‐3.12 GHz), and a 3‐dB axial‐ratio bandwidth of 38.7% (2.53, 2.04‐3.02 GHz). [ABSTRACT FROM AUTHOR]

Gain augmentation of a dual‐band antenna with different bandwidths using superstrate is presented in this paper. Initially, the dual‐band radiator is designed using a rectangular dielectric resonator (DR). The fundamental mode TE111 of the rectangular DR resonates at 3 GHz over a narrowband (BW = 5.08%). The upper wideband (BW = 20% with center frequency 5.86 GHz) is obtained by the amalgamation of two hybrid modes with higher‐order TE113 mode. The dielectric waveguide model is used for the theoretical analysis of two radiating modes of the rectangular DR. Further, a dual‐band frequency selective surface with bandpass response is designed and loaded as a superstrate above the DR antenna for gain improvement in both the bands, which leads to a gain augmentation of 1.8 dBi and upto 3.5 dBi in the lower and upper band respectively. At last, the proposed design is implemented practically, and measurement results are portrayed to compare with simulation results that agree reasonably well. [ABSTRACT FROM AUTHOR]

A new design of a compact dielectric resonator (DR) wideband antenna, catering the ultra‐wideband (UWB) spectrum and beyond, along with dual‐band circular polarization characteristics is presented in this literature. The antenna is realized by placing a pair of orthogonally placed DRs over a planar "I"‐shaped monopole. Fundamental modes of TE10δ (TE10δx and TE10δy) and TE11δ (TE11δx and TE11δy) are excited at 3.8 and 6 GHz by incorporating a pair of orthogonally placed DRs that generate the lower and upper band of circular polarization, from 3.7 to 4.4 GHz (17.28%) covering downlink and from 5.8 to 6.2 GHz (11.56%) for uplink C‐band communication satellites. The antenna provides an overall impedance bandwidth of 2.1 to 13 GHz (146.33%), thus covering UWB and lower end of the Ku‐band. Novelty of this work lies in achieving UWB and dual‐band circular polarization characteristics in a single antenna system. [ABSTRACT FROM AUTHOR]

A wideband ultrathin frequency selective surface (FSS) structure is designed and developed for the complete X‐band. The design employs a metallic tetra‐arrow (two bidirectional arrows placed diagonally) and a circular split structure (metallic) in the top side and bottom side of RT duroid 5880LZ low‐loss substrate respectively. The proposed design has novel contribution in terms of significant reduction in electrical thickness (0.007λ0 which is corresponding to lowest operating frequency, 8.3 GHz) and wider transmission (S21) bandwidth (measured: S21 ≤ − 10 dB, 8.15‐13.2 GHz, 47.3%), covering entire X‐band due to cumulative loading of surface mount chip resistors in the top layer. The principle of operation of the proposed FSS further can be justified with its equivalent transmission line circuit model, which is based on microwave filter (band‐stop and band‐pass) topology for anticipating the desired characteristics. The FSS structure is further integrated with dielectric resonator (DR)‐slot hybrid antenna for enhancing the gain (measured: peak gain of 4.5 dBi without FSS and 7.8 dBi with FSS) of the antenna. The proposed FSS structure is fabricated and measured performance has very similar responses as simulated ones. [ABSTRACT FROM AUTHOR]

In this paper, a broadband dielectric resonator antenna (DRA) with a simple H‐slot feeding structure is proposed. The broad bandwidth (~45%) and uni‐directional radiation enable this DRA suitable to work as a radiation element in the construction of a beam‐scanning array with not only low frequency sensitivity which is important for accurate angle estimation of in‐coming targets, but also a wide scanning range. Moreover, stable coupling coefficients are established around all the above three resonances with respect to its corresponding feeding line, ensuring a low sidelobe level (SLL) across the whole operating frequency range. In order to realize such a DRA, a latticed rectangular structure is utilized to generate the lower two resonances, while the upper resonance is generated by its H‐shaped feeding slot. The shape of the latticed dielectric resonator is also modified according to a 3‐D printed fixing structure for an accurate installation. A 20‐element beam‐scanning prototype is demonstrated and manufactured. The range of scanning angle is from −36° to +13° within the bandwidth of 10 to 16 GHz, corresponding to a frequency sensitivity of only 122.5 MHz/o. The achieved SLL are smaller than 19 dB for all scanning beams. The above performance indicates that, this array is very suitable for near‐range radar systems requiring an accurate angle estimation. [ABSTRACT FROM AUTHOR]

The article presents an asymmetric single split resonator (ASSR) unit cell, its resonant properties, and an electrically small microwave sensor employing the complementary asymmetric single split resonator (CASSR) structure with high quality factor (Q) on the FR4 substrate. The structure is compared with the conventional symmetric split ring resonator. The CASSR sensor designed and fabricated on a substrate of dielectric constant 4.4 and a thickness 1.6 mm has an electrically small size of 0.127λ0 × 0.127λ0 × 0.007λ0 at 1.27 GHz, which yields ka = 0.56 < 1 with low radiation efficiency. The properties and performance of the proposed CASSR for extracting the permittivity of both solid and liquid samples using amplitude and phase sensing in a simple lab‐in‐touch approach are validated with full‐wave simulations and experimental results. [ABSTRACT FROM AUTHOR]

A filtering antenna using dielectric strip resonator and parallel microstrip feed line is proposed to achieve compact dielectric size and filtering response without gain reduction. The compact dielectric size is contributed by the dielectric strip resonator with high permittivity operated in the TMδ1 cavity mode, whose electric field distribution along the short side is far less than half‐wavelength distribution. Therefore, the size of the proposed dielectric strip resonator is smaller than the traditional dielectric patch resonator operated in the TM11 cavity mode. Additionally, the parallel placed microstrip line not only can excite the dielectric strip resonator for filtering response without gain reduction, but also can provide one upper‐edge radiation null for frequency selectivity enhancement. Compared with the reported filtering dielectric antennas, the proposed design exhibits the features of compact dielectric size, simple structure and wide stopband. For demonstration, one prototype operating at 4.9 GHz is fabricated, achieves the dielectric size of 0.00078 λ3 0 (λ0 is the wavelength in the free space at the center frequency), the measured peak gain of 7.1 dBi, the 10‐dB impedance matching bandwidth of 4%, the stopband (> 16 dB) up to 1.84 f0, and the cross‐polarization level of 20 dB within 3‐dB beam range. [ABSTRACT FROM AUTHOR]

For the first time, the rectangular dielectric resonator (DR) operating in higher‐order TE3δ1 mode is investigated and used as a magnetic‐dipole driver to design quasi‐Yagi antenna with high gain. For further enhancing the antenna gain, a near‐zero‐index (NZI) metamaterial (NZIM) is proposed instead of the traditional directors and put in the front of DR driver. It is a simple structure and composed of a set of the parallel metallic lines printed on a substrate along the end‐fire direction. Benefiting from the higher‐order mode operation of the DR and NZIM, the realized gain of the proposed antenna can reach 10.3 dBi, including the gain improvement of 2 dBi resulting from the employed NZIM. To verify the design concept, the prototype of quasi‐Yagi DR antenna with NZIM is fabricated and characterized. The measured results agree very well with the simulated results. [ABSTRACT FROM AUTHOR]

This research article reports a new Dielectric Resonator Antenna (DRA) with its Dielectric resonator (DR) modified to an "OM" shape for UWB (3.1‐11.1 GHz), to support high data rate multimedia applications for 4G/5G communications. The proposed DRA reports a peak gain of 7.68 dB and a dual polarization behavior for a frequency band from 6 to 11.1 GHz. It has overall antenna dimensions of 50 × 40 × 4.87 mm3 and is fabricated on a commercially available Rogers RT 5880 substrate (with εr = 2.2), which is fed using a microstrip feedline with a P‐type transformer that offers an input impedance of 50 Ω to the DR. A conformal strip between the feedline and the OM shaped DR improves the impedance matching at the UWB frequency response of the DRA. This UWB frequency response is mainly because of its optimized "OM" shaped DR structure that excites a TE111 mode at 4.9 GHz and two higher order modes TE211 and TE221 at resonant frequencies of 7.2 and 8.35 GHz, respectively. Additionally the proposed OM shaped DR also generates orthogonal modes of TE211x and TE211y at 6.5 and 7.2 GHz and TE221x and TE221y at 8.35 and 10 GHz, respectively. The proposed DRA therefore exhibits an elliptically polarized behavior with axial ratio bandwidth of 5.1 GHz (≤10 dB) from 6 to 11.1 GHz. A measured impedance bandwidth of 5.25 GHz from 3.8 to 9.05 GHz and 1.5 GHz from 10 to 11.5 GHz and a peak‐measured gain of 7.68 dB at 10.5 GHz (with an average gain of 4.6 dB) has been reported for the proposed DRA. An UWB performance, with good gain properties and an elliptically polarized behavior allows the proposed "OM" shaped DRA to be suitable for short range 4G/5G UWB wireless communications for future multimedia rich WPAN (wireless personal area networks), WLAN, Wi‐MAX, INSAT applications, satellite applications, and X band RADAR (for defense communication) applications. [ABSTRACT FROM AUTHOR]

The method of stacking dielectric resonators for designing multiband and wideband antennas has gained much attention in recent times. However, the existing works lack any theoretical framework for the prediction of resonant frequencies of such stacked structures. In this work, a formal analysis using a cavity model with the mode matching technique is presented to determine all the existing resonant frequencies of annular stacked cylindrical dielectric resonator antennas with and without air gap. The analysis is done separately considering the outermost sidewall of the stack as both perfect magnetic conductor and imperfect magnetic conductor. The theoretical findings are extensively validated against numerous simulations, as well as against a fabricated prototype. It is observed that the perfect magnetic wall condition provides results that are more accurate. The closed‐form equation derived in this work not only helps in accurately predicting the resonant frequencies but also reduces the run‐time manifolds compared to that of the existing trial and error based methods of design using software simulations. [ABSTRACT FROM AUTHOR]

This review article provides an extensive literature survey on the research progress of dielectric resonator antenna (DRA) at millimeter‐wave frequency band that includes concepts of DRAs, their empirical formulae and design methodologies for different shaped DRAs at 60 GHz frequency band. The different shaped DRAs such as cylindrical, rectangular, hexagonal, and octagonal at 60 GHz are designed, simulated and analyzed using CST microwave studio solver. The −10 dB impedance bandwidth of cylindrical, rectangular, hexagonal, and octagonal DRAs are 52.7 to 62.8 GHz, 57 to 62.2 GHz, 55.8 to 64.2 GHz, and 54.2 to 63.5 GHz, respectively. The idea behind getting broad impedance bandwidth is due to use of double‐layer substrate with different permittivity (εr1 = 4 and εr2 = 11.9). Empirical formulae are deduced for hexagonal and octagonal DRA, by studying the analogy of dielectric resonator geometry. Consequently, the mode of different shaped DRAs, that is, HEM111 and TE111 are investigated by the electric field and magnetic field distribution. With these analysis, a comprehensive research review over the period of the last two decades is carried for investigating various techniques, targeted to realized gain, circular polarization, and impedance bandwidth. Along with these analysis the state‐of‐the‐art at different shaped DRAs at mm‐wave frequency band are also reported. [ABSTRACT FROM AUTHOR]

In this article, a multiband high gain cylindrical dielectric resonator (CDR) integrated with conical horn antenna is reported. This antenna has been designed for multiband wireless frequency applications. To enhance the gain, modified conical‐shaped horn is integrated to the CDR. The proposed antenna resonates at 2.3, 3.5, 3.9, 7.5, 9.2, and 9.95 GHz, respectively. Antenna attains measured 14.1 dBi peak gain at 10.7 GHz resonant frequency. In all the frequency bands, antenna offers more than 80% radiation efficiency. Simulated and experimental results show a commendable agreement. This antenna covers LTE services, Citizens Broadband Radio Service, WiMAX, vehicular communication, cellular communication, and radar applications. [ABSTRACT FROM AUTHOR]

In this article, cylindrical segmented dielectric resonator antenna (CDRA) is proposed for ISM band applications. To obtain the proposed antenna, three different (120°, 60°, and 30°) segments of different cylindrical radius r1,r2, and r3 with stacked angular displacement are used for circular polarization with wideband frequency response. Quadrature phase shift of orthogonal field are observed when segment of cylinder is stacked with specific angular displacement. Various higher order modes are investigated. The simulated and measured impedance bandwidth of the proposed antenna is 90% (3.3 GHz‐8.7 GHz) and 83.4% (3.5 GHz‐8.5 GHz) respectively and the simulated and measured axial ratio bandwidth is 53.8% (3.8 GHz‐6.6 GHz) and 58.5% (3.5 GHz‐6.4 GHz), respectively. Proposed antenna attains 7.1 dBi measured peak gain at 8.5 GHz with more than 80% radiation efficiency in the frequency band. The fabricated prototype is experimentally measured and its results are found to be commensurable with the simulation results. [ABSTRACT FROM AUTHOR]

A dual‐port multiple‐input multiple‐output (MIMO) dielectric resonator antenna (DRA) for 5 GHz IEEE (802.11a/h/j/n/ac/ax) is discussed in this article. Two prototypes of single feed DRA and dual feed MIMO DRA are fabricated and measured results are compared with the simulated data. The proposed single feed DRA and dual feed MIMO DRA exhibits wide impedance bandwidth (IBW). Antennas have been fabricated on Rogers RT Duroid substrate with Eccostock made DRA placed over the substrate. DRAs are excited by aperture coupled feed to achieve wide bandwidth and high efficiency. The measured IBW of uniport DRA and dual‐port MIMO DRA are 26.6% (4.75‐6.21 GHz) and 27.5% (4.7‐6.2 GHz) respectively. Maximum gain of the antenna is 7.4 dBi. The results of the antennas are in good agreement with simulated data and they are suitable for WLAN applications. These antennas are also compact with area of substrate 32.8 cm2. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, two Dielectric Resonator Antenna (DRA) models fed through a pair of diagonally coupled asymmetric L‐slots are incorporated on the ground plane of size 44 X 44 mm2 with a strip line feed underneath the substrate are presented. The proposed DRA‐1 is a triband antenna, resonates at 5.2GHz, 6.7GHz and 9.85GHz with a gain of 5.6dBi, 5.66dBi and 9.8dBi respectively. The bandwidth offered at Circularly Polarized (CP) band by DRA‐1 is 1.95 GHz (6‐7.95 GHz). The proposed second model DRA‐2 operates at 5 GHz, 6.4 GHz, 7.8 GHz and 10.3 GHz with a peak gain of 5.5dBi, 5dBi, 6.1dBi and 7.8dBi respectively. The quad‐band DRA‐2 offers two CP bands with bandwidths of 1.3GHz (7‐8.3 GHz) and 1.2 GHz (9.8‐11 GHz). The multiple operating bands of the proposed DRAs are appropriate for different wireless applications such as WLAN, C‐Band and X‐Band range of frequencies. [ABSTRACT FROM AUTHOR]

Abstract: A physically accomplished truncated conical dielectric ring resonator (DRR) is designed and experimented to validate the performance parameters. The DRR loaded on brass ground plane fed by coaxial probe resonates in three frequencies: 12.5, 19.7, and 23.5 GHz. Among three resonances, the first one is radiating and shows reasonable broadside gain of 4.3 dBi. The higher resonances are nonradiating and offer very low gain. The frequency selective metasurface walls are realized by complementary split Ring resonators and positioned sensitively near the conical DRR. The gain performance at 12.5 GHz has been improved to 18 dBi with ‐10 dB impedance bandwidth of 900 MHz (12.2‐13.1 GHz) by incorporation of lateral frequency selective surface wall with suppression of higher nonradiating modes. The proposed antenna structure has been designed, simulated with the commercially available HFSS software to achieve the optimized dimension and validated with the measurement results. [ABSTRACT FROM AUTHOR]

Abstract: This article outlines a compressive review on investigation carried out targeting to gain, circular polarization (CP), and mutual coupling reduction in dielectric resonator antenna (DRA). The DRA has already been created a separate position in antenna engineering domain because of its adept characteristics, such as wide bandwidth, high efficiency, low‐loss, and mainly 3D‐design flexibility which is rarely available in conventional antennas. In this context, the research on gain, circular polarization, and mutual coupling are quite interesting and being carried out from the last two decades. The ultimate aim of this article is to (i) give an overview of different techniques adopted in context to gain, CP, and mutual coupling reduction; (ii) give a compressive review of notable research carried out targeting to these three characteristics; and (iii) find out the research gap concentration for furtherance of the same. [ABSTRACT FROM AUTHOR]

This letter investigates an integrated antenna configuration for WLAN/WiMAX applications. The proposed composite antenna configuration is simply the grouping of ring dielectric resonator along with reformed square-shaped slot antenna. Three significant characteristics of proposed article are: (1) aperture act as magnetic dipole and excite HE11d mode in ring dielectric resonator antenna; (2) reforming of square aperture generates orthogonal modes in ring DRA and creates CP in lower frequency band; (3) annular-shaped Microstrip line along with reformed square aperture creates CP wave in upper frequency band. With the purpose of certifying the simulated outcomes, prototype of proposed structure is fabricated and tested. Good settlement is to be got between experimental and software generated outcome. Experimental outcomes show that the proposed radiating structure is operating over 2 frequency bands that is, 2.88-3.72 and 5.4-5.95 GHz. Measured 3-dB axial ratio bandwidth in lower and upper frequency band is approximately 9.52% (3.0-3.4 GHz) and 5.85% (5.64-5.98 GHz), respectively. These outcomes indicate that the proposed composite antenna structure is appropriate for WLAN and WiMAX applications. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we investigate an optically transparent broadband water antenna, which is composed of a cross‐shaped slot feeding structure and a thin layer of water supported by a transparent dielectric slab. This water antenna can be analyzed as an embedded stacked dielectric resonator (DR) antenna (DRA) mounted on a ground plane. Two distinct resonator modes—namely, DRA mode and dielectric‐loaded slot (DLS) mode—are excited to achieve a good impendence matching over a very wide frequency range. A prototype antenna is designed, fabricated, and measured. Measured results demonstrate that the designed water antenna exhibits a broad impedance bandwidth of about 37% from 1.07 to 1.56 GHz with antenna efficiency better than 65% and broadside radiation characteristics with low cross‐polarizations. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a coaxial probe fed wideband circularly polarized antenna has been designed and investigated using unequal and adjacent‐slided rectangular dielectric resonators radiating in broadside direction (Φ = 0°, θ = 0°). Wi‐Fi wireless network use radio signal either in 2.4 or 5 GHz band. Owing to high rush in 2.4 GHz band, the proposed antenna is designed for 5 GHz (5.15‐5.825 GHz) WLAN band. The proposed design uses fundamental orthogonal modes TE δ 11 X and TE 1 δ 1 Y excited in two individual rectangular dielectric resonators to achieve wide axial‐ratio bandwidth (below 3 dB). Measured input reflection coefficient (below −10 dB) and axial ratio bandwidth (below 3 dB) of 26.07% (5.27‐6.85 GHz) and 26.85% (5.32‐6.97 GHz) has been attained, respectively, in this proposed antenna. The measured far‐field patterns such as gain and radiation patterns are showing consistent performance throughout the working band. [ABSTRACT FROM AUTHOR]

In this article, a wideband circularly polarized half-split cylindrical dielectric resonator antenna (HS-CDRA) having two layers with different permittivity in radial direction is investigated. Designed antenna is excited by a new modified CPW fed which consists of signal line, helps to realization of circular polarization, half-split cylindrical dielectric resonator (HS-CDR), to confirm that circular polarization in proposed antenna. HS-CDR is made of two different materials which can supports to enhance the input impedance bandwidth and 3-dB axial ratio bandwidth. From the distributions of E-fields in HS-CDRA, it is observed that TM11 δ mode has been excited. To confirmed the circular polarization in proposed antenna, E-field distribution on different phases (φ = 0º, 90º, 180º, and 270º) have been plotted. This antenna provides measured −10 dB input impedance bandwidth of 25.94% (centered on 4.70 GHz) and 3-dB axial ratio bandwidth in broadside direction of 17.34% (centered on 4.90 GHz). The average gain and radiation efficiency in working band are 1.56 dBi and 93.43% in broadside direction, respectively. CP radiation pattern shows that the proposed antenna has left hand circular polarization and this developed antenna could be useful for wireless applications like WLAN/Wi-MAX bands. [ABSTRACT FROM AUTHOR]

This survey article outlines a comprehensive investigation of research carried out on dielectric resonator antennas (DRAs) in the last three and half decades, in an application-oriented approach. DRAs have created a remarkable position in antenna engineering for their adept characteristics like high efficiency, low loss, wide bandwidth, compact size, 3-dimensional modeling flexibility, etc. The use of DRAs for different commercial and defense applications associated with the wireless communication is highlighted in this article. To make a smooth and effective survey article, all the application-oriented DRAs available in the open literature are classified in five different categories like microwave bands, specific frequency, technology, millimeter-wave, and miscellaneous types. The ultimate aims of this review article are as follows: (i) highlights the usability of DRAs for different commercial and defense applications, (ii) helpful for the antenna industries/manufacturers to find out the best DRA for any specific application as per their requirement, and (iii) points out research gap in some application domains which will be quite helpful for future antenna researchers. In the authors' opinion, this survey may be helpful to DRA researchers as such a survey process is not available in the open literature. [ABSTRACT FROM AUTHOR]

A novel dual-band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications is designed and investigated. The proposed antenna operates at 3.5 and 5.25 GHz bands. High port isolation is achieved using hybrid feeding mechanism that excites two orthogonal modes at each frequency bands. The measured impedance bandwidth of the proposed antenna covers the entire WiMAX (3.4-3.7) GHz and WLAN (5.15-5.35) GHz bands. The scalable behavior along with the frequency ratio of the antenna has also been investigated in this work. The measured isolation between antenna ports is −52 dB at the lower band and −46 dB at the upper band, respectively. Envelope correlation coefficient, diversity gain and mean effective gain have also been investigated. Moreover, measured results are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

This article presents a comparative analysis for the performance of single, 2 × 2, and 4 × 4 dielectric resonator (DR) and patch circularly polarized (CP) antenna subarrays at 30 GHz. In order to enhance the CP bandwidth, the subarray elements are fed by two kinds of sequential feeding techniques using parallel and hybrid ring feeds. The 4 × 4 patch antenna subarrays fed by parallel and hybrid ring feeding networks are fabricated and tested. Measurements show acceptable agreement with simulation results. The experimental results show a bandwidth of 36.9% for both (−10 dB) impedance matching and (3 dB) axial ratio CP patterns for the patch subarray antenna with hybrid ring feeding. For the parallel feeding, the corresponding bandwidth is 28.81%. The proposed antennas combine desirable features such as wide impedance and AR bandwidths, low profile, and easiness of fabrication and therefore is a good candidate for millimeter wave systems around 30 GHz. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a novel coupling method which could easily change the coupling nature between two TE01 δ-mode dielectric resonators (DRs) is presented. This method is based on electric field orientation of DR operating in TE01 δ-mode, through altering the direction of the coupling structure in one DR, the coupled electric field orientation in the other DR would be changed along with the coupling nature between two resonators. To prove this method, two filters using cascaded quadruplet coupling structure have been designed, fabricated and measured. The coupling strength is enhanced due to the employ of two grounded mental cylinder on both sides of the copper sheet. In addition, a tuning screw is introduced between two DRs to adjust the coupling strength after mounting expediently. Measured results confirmed the predicted performance, showing that the coupling nature and coupling strength are controllable between two DRs. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:226-231, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a hybrid two segments ring dielectric resonator antenna with partial ground plane, for ultrawideband application is described. The proposed antenna structure consists of annular shape microstrip line along with two ring dielectric resonators having different permittivity. By applying the combination of shifted annular shape microstrip line (used as a radiator as well as to convert TM01 δ mode to TE01 δ mode) and two segments ring dielectric resonator, ultra wide bandwidth has been achieved. Prototype of proposed structure has been fabricated and tested. Measured results show good agreement with the simulated ones. The proposed antenna structure operates over a frequency range of 3.45-10.9 GHz with a fractional bandwidth of 103.83% and having better gain and radiation characteristics. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:47-53, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the design of a six pole Chebyshev filter and a cascaded quadruple dielectric resonator (DR) filter using space mapping technique. Implicit space mapping technique is used throughout and the design emerges within few iterations in both the cases. Finite element method based HFSS is used in constructing the fine model and Agilent ADS is used in constructing the coarse model. Fine details such as tuning screws are included in the fine model. The same technique is also applied to a DR-based diplexer and is explained. In all the cases, the results obtained with the hardware match well with the analyzed results. The same procedure can be applied in designing much more complex structures such as multiplexers. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:204-216, 2014. [ABSTRACT FROM AUTHOR]

ABSTRACT The modulation of a microwave-scale Mach-Zehnder interferometer coupled to a dielectric resonator (DR) tunes the DR resonance frequency. We report on a theoretical study to develop an understanding of the intrinsic tuning properties of an Mach-Zehnder interferometer ring-DR-microstrip line system and present an experimental verification. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:229-236, 2014. [ABSTRACT FROM AUTHOR]

A miniaturized dual-band C-shaped dielectric resonator antenna (DRA) with partial ground plane is presented for IEEE 802.16d fixed WiMAX applications at 3.5 and 5.8 GHz. The design starts with dimensioning a single band cylindrical DRA, which has been transferred to get a dual-band ring-shaped DRA. One portion of the ring-shaped DRA is removed for forming a C-shaped DRA to get a more compact antenna. For easy fabrication, the compact DRA dimensioned as 60 × 50 × 6.6 mm3 is excited by a microstrip line feeding. The design parameters are inner and outer radii of the C-shaped antenna and air gap (between DR and ground) to control both the resonating frequency and the quality factor. The result shows peak gain around 3.26 and 5.55 dBi at 3.5 and 5.8 GHz, respectively. The obtained results indicate very good agreement between the simulated and measured results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 682-689, 2012. [ABSTRACT FROM AUTHOR]

This article presents a novel compact circularly polarized antenna with wideband operation. The proposed antenna consists of a microstrip-line-fed printed monopole, a finite truncated ground, and a dielectric resonator (DR). Compared to the printed monopole antenna, the proposed DR-loaded antenna has an increased impedance bandwidth, a large axial ratio bandwidth, and a good realized gain across the desired frequency range. An antenna prototype is fabricated and experimentally tested. The measured antenna impedance match is better than −10 dB over 90% from 4.5 to 11.8 GHz frequency band and the 3-dB axial-ratio bandwidth is better than 35% covering the 5.4-7.65 GHz frequency band. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012. [ABSTRACT FROM AUTHOR]

In this article, a modified fractal rectangular curve (FRC)-shaped dielectric resonator antennas (DRA) with two different functionalities is reported. These antennas are split in the middle into two halves and are excited by a coaxial probe. In first configuration, the fractal geometry is used to achieve wide bandwidth from 3.5 to 5.0 GHz covering the body area network frequencies as well as the IEEE 802.11a WLAN frequencies. The average peak gain within the band is about 7 dBi. The second investigation involves miniaturization of rectangular DRA by using FRC along the cross-sectional boundary. By this, a DRA at 3.2 GHz could be realized using second iteration of modified rectangular curve fractal geometry resulting in a 50% size reduction by maintaining same radiation characteristics. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. [ABSTRACT FROM AUTHOR]

An innovative technique of neural network optimization of substantially less computational cost is presented as a procedure suitable for viable computer-aided design of complex microwave systems. The number of necessary full-wave simulations in this optimization procedure is dramatically reduced because of a special objective function (OF) and constrained optimization response surface (CORS) sampling in the dynamic training of the decomposed radial-basis-function network. A high rate of convergence to an optimization objective is shown to be dependent on the combined effect of the OF and CORS technique. Performance of the algorithm is illustrated by its application to a waveguide band-pass filter, a loaded microwave oven, and a dielectric resonator antenna; their optimal designs are found from five-parameter optimizations requiring as little as 167, 177, and 99 analyses, respectively. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. [ABSTRACT FROM AUTHOR]

A novel approach for shape optimization of dielectric resonators is presented with an objective of improving their unloaded quality factor. Shape (level-set) and topology (topology gradient) optimization methods coupled with finite element method are utilized together, which as a result, relaxes the traditional trade-off made between the spurious-free band (isolation) and the high unloaded quality factor of the resonators. The defined cost function is minimized by the proposed iterative coupling between the level-set method and the topology gradient method. The optimized resonator, which improves the unloaded quality factor of about 65% compared with the reference, is then approximated for fabrication. The reference, optimized, and approximated resonators are fabricated and measured. Results from the simulated and the fabricated resonators validate the optimization approach presented in this work. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. [ABSTRACT FROM AUTHOR]

In this article, a freeware tool for computer-aided design and analysis (resonant frequency and unloaded Q-factor) of dielectric resonators for antenna applications is presented. Several resonator shapes, including hemispherical, cylindrical, cylindrical ring, and rectangular cross-section, are supported. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2010. [ABSTRACT FROM AUTHOR]

Dielectric resonator antennas with fractal cross sectional areas have been investigated. Two main configurations of these novel types of dielectric resonator antennas have been examined. Analyses of these proposed dielectric resonator antennas are performed numerically using the finite element method and verified by the finite integration technique. Agreement between the methods is excellent. The effects of antenna parameters, such as fractal iteration level and tapering rate of dielectric resonator, are investigated. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [ABSTRACT FROM AUTHOR]