Wideband circular polarized cylindrical segmented dielectric resonator antenna for ISM band applications

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 r_1, 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.     

Hybrid cylindrical dielectric resonator antenna with HE11δ and HE12δ mode excitation for wireless applications

In this article, dual mode triple band hybrid cylindrical dielectric resonator antenna (CDRA) for different wireless applications is investigated. It is seen that annular ring shaped patch along with T‐shaped printed line behaves as a magnetic and electric dipole concurrently and create HE_11δ and HE_12δ mode in the proposed CDRA. Both of the hybrid modes radiate in broadside direction. The concept of hybrid antenna (the combination of annular ring patch and CDRA) is used to achieve triple‐band feature in the proposed antenna. Ansoft HFSS‐EM simulator is used to optimize the proposed antenna. Optimized simulated results have been practically confirmed by using the archetype of proposed antenna. The proposed radiator is applicable in three different frequency bands, that is, 2.24‐2.56 GHz, 3.28‐4.18 GHz, and 5.36‐5.8 GHz. It is appropriate for WLAN (2.4/5.8 GHz) and WiMAX (2.5/3.3/5.5 GHz) applications.     

Dual segment rectangular dielectric resonator antenna with metamaterial for improvement of bandwidth and gain

The simulation and experimental studies of an aperture‐coupled wideband dual segment rectangular dielectric resonator antenna with metamaterial for C‐band applications are presented in this paper. The antenna consists of Alumina (Al₂O₃) ceramic as upper segment and Teflon as lower segment. The combination of circular‐shaped coplanar split‐ring resonator and conducting strip has been used as metamaterial superstrate. With the use of metamaterial superstrate, the bandwidth of the antenna is increased by 48% through simulation and 22% experimentally. The broadside radiation pattern of the antenna is converted into directive radiation pattern with reduced beamwidth when metamaterial superstrate is used. The peak gain of the antenna is also enhanced by 33% through simulation and 31% experimentally with the use of metamaterial superstrate. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:646–655, 2014.     

Wideband high gain conical dielectric resonator antenna: An experimental study of superstrate and reflector

A physically feasible new hybrid geometry for gain improvement with wideband characteristics is designed and validated experimentally in a conical shaped dielectric resonator antenna (DRA). It comprises of one superstrate and one reflector, with simple slot coupling technique for excitation. The reflector beneath the ground plane mainly accountable for significant gain improvement (～109%) by reducing the back radiation, whereas the superstrate dedicates for maintaining wideband (12.65%). The demonstrated result shows S ₁₁ < ?10 dB band between 7.4 GHz and 8.4 GHz, with 11.25 dBi peak gain, which are well matched with their simulated counter parts. It also gives high co‐pol to cross‐pol difference (～40 dB) in broadside direction. This new geometry can be eligible for X‐band applications as well can usher the DRA researchers for further innovations.     

Wideband circularly polarized concentric cylindrical dielectric resonator antenna excited by helix

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 (HE_11δ) 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.     

High‐gain compact rectangular dielectric resonator antenna using metamaterial as superstrate

A compact high‐gain rectangular dielectric resonator antenna (RDRA) using metamaterial (MTM) as superstrate for C‐band applications is proposed in this article. The proposed antenna consists of coaxial‐fed RDRA with 50 unit cells of MTM arranged in 5 × 10 layout as superstrate. Each unit cell is constructed of two parallel eight‐shaped copper strips printed over both faces of a dielectric substrate to provide negative refractive index from 7.3 to 8.1 GHz covering the maximum bandwidth of RDRA. The extracted lumped equivalent circuit model of unit cell of MTM shows concurrence with electromagnetic simulations. The use of MTM superstrate increases the peak gain of the antenna by 89% through simulation and 86% experimentally. The measured results show that the proposed antenna achieves an impedance bandwidth of 16.1% over a band of 7.18‐8.44 GHz, with a peak gain of 14 dBi at 7.8 GHz.     

Dual‐band circularly polarized dielectric resonator antenna for wireless applications

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 HE_11δ 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.     

Investigations on modified rectangular fractal curve shaped dielectric resonator antenna

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.     

Electrically coupled dual semicylindrical dielectric resonator antenna with inverted arrangement for wideband applications

In this article, an electrically coupled dual semicylindrical dielectric resonator antenna (SC‐DRA) is presented and discussed for wideband applications. The two SC‐DRAs are placed in an inverted arrangement and fed by a coaxial probe to excite the fundamental mode TM _11δ and higher order mode TM _21δ. In the proposed design, wideband performance is obtained by combining the fundamental and higher order mode. Proposed wideband antenna is showing simulated and measured input impedance bandwidth (|S₁₁| ≤ ?10 dB) of 57.94% (3.8‐6.9 GHz) and 64.4% (3.38‐6.6 GHz), respectively. The far field radiation patterns are found to be consistent and 3‐dB beamwidth of 49° and 30° has been achieved at 4.11 and 6.48 GHz, respectively within the working band. This design attains an average gain of 5.65 dBi and radiation efficiency of 97%, respectively.     

Dielectric resonator array antenna for triple band WLAN applications with enhanced gain

An H‐shaped dielectric resonator array antenna is presented for wideband applications. The proposed antenna is excited by slot feed mechanism and investigated experimentally. The antenna covers the frequency ranges from 1.41 to 2.59 GHz, and 4.73 to 6.06 GHz with the corresponding impedance bandwidth of 59% and 24.65%, respectively. The simulation results fulfill the bandwidth requirements of IEEE 802.11a/b/g (2.4‐2.484 GHz/5.15‐5.35 GHz/5.725‐5.825 GHz) for Wireless local area network (WLAN) applications. The proposed antenna has simple structure, easy to fabricate and its measured radiation pattern shows a reliable performance in the desired operating bands.     

A broadband inverted umbrella shaped cylindrical dielectric resonator antenna for “WLAN” and “C” band applications

The main objective of the present article is to improve the bandwidth of a low profile Cylindrical Dielectric Resonator Antenna (CDRA) and operate it for WLAN and “C” band applications. An inverted umbrella shaped CDRA excited by a microstrip feedline with single stub is proposed here. Efficient coupling has been achieved by means of a single stub microstrip feed between DRA and the feed. The new shape of DRA and a single stub microstrip feed improves the bandwidth significantly as high as 28% from 5 to 6.67 GHz which is quite useful for both WLAN and “C” band applications. The proposed antenna is simple in construction, easy to fabricate, low profile and thickness of CDRA is only 5 mm. A parametric study is performed using Ansoft HFSS simulation software to optimize the antenna performance. The proposed CDRA is fabricated and the characteristics of the antenna are measured.     

Wideband circularly polarized dielectric resonator antenna loaded with partially reflective surface

A wideband circularly polarized (CP) dielectric resonator antenna (DRA) loaded with the partially reflective surface for gain enhancement is presented in this article. First, the DRA is excited by a microstrip line through modified stepped ring cross‐slot to generate the circular polarization. Four modified parasitic metallic plates are sequentially placed around the DRA for greatly widening the axial‐ratio bandwidth. Then, a partially reflective surface is introduced for enhancing the gain performance and further improving the CP bandwidth as well. Finally, an optimized prototype is fabricated to verify the design concept. The measured results show that the proposed DRA achieves 54.3% impedance bandwidth (VSWR<2) and 54.9% 3‐dB AR bandwidth. Besides, its average and peak gains are 10.7 dBic and 14.2 dBic, respectively. Wide CP band and high gains make the proposed DRA especially attractive for some broadband wireless applications such as satellite communication and remote sensing.     

Switched beam dielectric resonator antenna array with six reconfigurable radiation patterns

A single feed, four element rectangular Dielectric Resonator Antenna (DRA) array, with beam switching capability is proposed. A wide impedance bandwidth of more than 25% at the center frequency of 1.95 GHz is achieved. Each DRA has two excitation strips and four parasitic patches. The six cases are discussed; each case corresponds to a diverse radiation pattern. The antenna beam is switched in azimuth (θ = 45°) at Φ = 0°, 60°, 120°, 180°, 240°, and 300°. The antenna gain is found to be more than 7 dB in most of the frequency band of interest. A passive prototype is developed and tested to validate simulation results. The comparison between the simulated and measured reflection coefficients and the radiation patterns for the six cases is presented. A good agreement between the measured and simulated results is observed. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:519–530, 2016.     

A wideband stacked dielectric resonator antenna for 5G applications

A wideband stacked dielectric resonator antenna with stable patterns is proposed for fifth‐generation of mobile technology in this paper. With the help of inserted air gaps to reduce the radiation Q factor, the stacked structure with two thin high permittivity sheets and two hollow low permittivity slabs can provide four adjacent resonant modes to form a wide bandwidth. Measured results demonstrate that the antenna obtains an impedance bandwidth of 54% for |S₁₁| < ?10 dB and a peak gain of 9.2 dBi. The radiation patterns remain stable and symmetrical over the entire operating band.     

Wideband circularly polarized hybrid dielectric resonator antenna with bi‐directional radiation characteristics for various wireless applications

In this article, a wideband circularly polarized (CP) dielectric resonator (DR) over an asymmetric‐slot radiator based hybrid‐DR antenna is proposed with bi‐directional radiation characteristics. Bi‐directional CP radiation of the dual sense is obtained using a rectangular‐DR over asymmetric‐rectangular‐slot radiator with L‐shaped feed line. The asymmetric‐slot radiator feed by L‐shaped stub with the coplanar waveguide is used for generating two orthogonal modes, namely TE ^x _δ11 and TE^y_1δ1 in the combined (rectangular‐DR and asymmetric‐slot radiator) hybrid‐DR antenna, which is verified by the distribution of electric field inside the rectangular DRA. The measured reflection coefficient bandwidth (S₁₁ < ?10 dB) and axial ratio (AR) bandwidth (AR < 3 dB) of the hybrid‐DR antenna are 80.5% (1.87‐4.39 GHz) and 43.8% (1.75‐2.73 GHz), respectively. The antenna radiation is in the broadside (θ = 0°, ? = 0°) direction as well as in the backside (θ = 180°, φ = 0°) direction with equal magnitudes in both the directions. Right‐handed and left‐handed CP waves are achieved respectively, in the boresight (+Z) and the backside (?Z) directions. The proposed CP hybrid‐DR antenna gives an average gain of 3.55 dBic and radiation efficiency of 95.0% in both directions. The proposed antenna covers various wireless useful bands such as ISM 2400 band, Wi‐Fi, Bluetooth, and Wi‐MAX (2.5‐2.7 GHz).     

Rod-ring dielectric resonator antenna

A dielectric resonator combining two cylindrical dielectrics of different material and height and excited by a coaxial probe is considered. The effect of the antenna parameters, such as the ratio of the height and radius of the dielectrics and the effect of the probe length, are investigated. Analysis of the antenna is performed numerically using the method of moments (MoM) and verified by the finite-difference time-domain (FDTD) method. Agreement between the two methods is excellent. The performance of the antenna on a cellular-communication system is also considered. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 441–446, 2004.     

Variation of permittivity in radial direction in concentric half‐split cylindrical dielectric resonator antenna for wideband application

Design and development of wideband concentric half‐split cylindrical dielectric resonator antenna (CDRA) using permittivity variation in radial direction has been proposed in this article. The homogeneous, two‐layer and three‐layer concentric half‐split CDRAs have been discussed separately. The effect of antenna parameters such as layer arrangement, geometrical parameters, and probe length are investigated. To validate the results, two‐layer and three‐layer concentric half‐split CDRA have been fabricated using commercially available microwave laminates. In each case, the input reflection coefficient, radiation pattern, and antenna gain are simulated and measured. Good agreements between simulated and measured results have been obtained. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:321–329, 2015.     

Tri‐band composite cylindrical dielectric resonator antenna with hybrid mode excitation and cross‐polarization suppression

This communication investigates composite cylindrical dielectric resonator antenna (CDRA) for various wireless applications. Three important features of proposed antenna design are (i) realization of two different hybrid modes, that is, HEM_11δ and HEM_12δ mode in CDRA with the help of modified annular ring printed line (work as both magnetic dipole and electric dipole), both the hybrid modes support broadside radiation characteristics (ii) suppression of HEM_21δ mode, in order to reduce the cross‐polarization level in H‐plane of other hybrid modes (HEM_11δ and HEM_12δ mode) by an amount of 8‐10 dB (iii) creation of triple‐band attribute using the concept of composite antenna. The proposed antenna design has been fabricated and practically tested. Simulated outcomes show good agreement with measured outcomes. It works in three frequency bands, that is, 2.25‐2.79 GHz, 3.1‐4.0 GHz, and 5.05‐5.6 GHz. The designed antenna structure is appropriate for WLAN and WiMAX applications.     

Design of a dual‐band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications

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.     

Investigation on novel wideband fractal antenna design based on cylindrical shape dielectric resonator

This article explains a novel approach for achieving wideband characteristics in case of dielectric resonator antenna (DRA). Wideband characteristic has been realized by uniting the concept of vastu purusha mandala (VPM)‐based fractal geometry with dielectric resonator antenna. VPM is Hindu religion‐based fractal geometry, which provides the advantage of decrease in volume to surface area of the radiator. This concept is useful to enhance impedance bandwidth of proposed antenna. For the purpose of validation, prototype of proposed antenna design has been fabricated as well as tested. After experimental testing, it is confirmed that the proposed radiator functions over the frequency range 2.6‐4.34 GHz with a percentage bandwidth of 46.52%. The proposed radiating arrangement provides peak gain of 6.3 dBi and stable far‐field characteristics. All these features make it applicable for WiMAX application (3.3 GHz).