Wideband circularly polarized square dielectric resonator antenna for WLAN/WiMAX applications

In the present article, a novel single fed square dielectric resonator antenna (SDRA) is presented and two orthogonal modes ( ${\mathrm{TE}}_{111}^{\mathrm{x}}\text{and}{\mathrm{TE}}_{111}^{\mathrm{y}}$) of SDRA are utilized to produce the wideband circular polarization. To generate circular polarization over a broad frequency band, a new technique known as hybrid DRA has been proposed in this article. In this technique, the feeding circuit act as a radiator and also provides feeding to the dielectric resonator which enhances the impedance and axial ratio bandwidth. A 3‐dB axial ratio bandwidth of 26.66% is achieved by the SDRA excited through a rectangular patch united with 50 Ω microstrip line. In order to further increase the axial ratio bandwidth from 26.66% to 48%, a notch is truncated from the rectangular patch. The design antenna prototype has been fabricated and experimentally tested. Experimental results illustrate that the proposed structure has broad impedance and axial ratio bandwidth of 75.86% and 43.75%, respectively, and the entire axial ratio bandwidth fully matched with the impedance bandwidth. The proposed antenna produces a right handed circularly polarized (RHCP) field. By taking the mirror image of the proposed microstrip feeding, the RHCP field is converted into left handed circularly polarized (LHCP) field. This antenna is preferred for wireless applications such as indoors communication, remote sensing, wireless sensor systems and WLAN/WiMAX applications.     

A new dual‐mode wideband circularly polarized rectangular dielectric resonator antenna coupled with stubs and asymmetric ground plane for WiMAX applications

In this article, a new radiating stub microstrip feed has been investigated with asymmetrical ground plane for generation of circular polarization (CP) in a dielectric resonator antenna (DRA). Here, asymmetrical ground plane and 3 radiating stubs with microstrip feed line are used for generation of 2 different modes namely TE_11δ and TE_12δ in rectangular DRA. By using mode matching concepts, these modes are responsible for enhancing the impedance bandwidth (TE_12δ ie, and ) and axial ratio (AR) bandwidth (TE_11δ ie, and ) in proposed antenna. Designed antenna offers measured input impedance bandwidth (|S₁₁| < ?10 dB) and AR bandwidth (AR < 3‐dB) of 44.78%, ranging from 4.6 to 6.9 GHz and 23.32%, ranging from 4.6 to 6.9 GHz, respectively. It has been observed that proposed antenna shows left‐handed CP fields in boresight direction with average gain of 3.15 dBic and radiation efficiency of 90.54%. Designed antenna is suitable for Wi‐MAX (3.3‐3.7 GHz) applications.     

Wideband circularly polarized rectangular DRA fed with dual pair of right‐angled microstrip line

In this article, design and development of wideband circularly polarized (CP) rectangular dielectric resonator antenna (RDRA) is presented. To generate wideband CP in proposed antenna, different feeding mechanism have been studied. Three antenna configurations based on different feeding have been discussed using single and dual pair of microstrip lines aligned perpendicular to each other to generate orthogonal modes resulting in circular polarization. It has been claimed here that excitation of RHCP/LHCP field and its direction of radiation could be controlled using height of microstrip feed lines. Finally antenna configuration‐3 is fabricated and measured which shows 36.8% of input impedance bandwidth (3.48–5.05 GHz) and axial ratio bandwidth of 14.46% (3.67–4.24 GHz) in broadside direction (at Φ = 0°, θ = 0°). The final proposed structure exhibits consistent far‐field characteristics with average LHCP gain of 6.4 dB and almost stable radiation efficiency in entire operational frequency range. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:713–723, 2016.     

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.     

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.     

Hybrid wideband dual‐cylindrical circularly polarized dielectric resonator antennas excited with S‐shaped microstrip feed for sub‐6 GHz frequency range

In this article, a hybrid microstrip fed dual‐cylindrical dielectric resonator antenna (dual‐CDRA) has been proposed for the sub‐6 GHz band application with a wide circular polarization band. The proposed hybrid microstrip feed cylindrical dielectric resonator antenna utilizes an S‐shaped microstrip feed line to excite fundamental HE_11δ like mode and hybrid mode in dual‐CDRAs. The presented antenna structures are acting as monopole antenna separately with 48.75% (3.88‐6.38 GHz) bandwidth whereas both radiators called dual‐CDRAs enhances the bandwidth up to 93.06% (2.16‐5.92 GHz) in addition with an axial ratio bandwidth of 15.2% (3.52‐4.1 GHz). The proposed antenna is applicable for WiMAX (3.4‐3.69 GHz), and WLAN application of 802.11d and 8.02.11e IEEE standard. For validation of simulated results, an antenna prototype has been fabricated and experimentally verified. A good agreement between simulation and measured results are obtained. The simulation results have been carried out by using Ansys HFSS 14.0 version software.     

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.     

A coaxial probe fed wideband circularly polarized antenna using unequal and adjacent‐slided rectangular dielectric resonators for WLAN applications

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 and 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.     

Circularly polarized rectangular dielectric resonator antenna fed by a cross aperture coupled spiral microstrip line

In this article, a circularly polarized rectangular dielectric resonator antenna fed by a cross‐aperture coupled spiral microstrip line is investigated. A quarter wavelength section of microstrip line is positioned between each arm of the cross slot in a spiral form to generate the circular polarization. The prototype of proposed antenna is fabricated and tested. The measured |S₁₁| and 3‐dB axial ratio frequency range is 31.74%, (2.65–3.65) GHz and 20%, (3.12–3.74) GHz, respectively and the measured total gain and left handed circularly polarized gain are 4.5 and 3.1 dB, respectively. The proposed antenna may be suitable for WiMAX applications.     

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.     

A novel millimeter‐wave dual‐band circularly polarized dielectric resonator antenna

In this article, a novel dual‐band circularly polarized (CP) dielectric resonator antenna (DRA) for millimeter‐wave (MMW) band is presented. The rectangular dielectric resonator with layered truncated corners is excited by a microstrip‐coupled cross‐slot. CP radiations in the lower band are realized by utilizing two quasi‐TE₁₁₁ modes operating at 21.7 GHz and 23.8 GHz, while CP radiations in the upper band are obtained by exciting a quasi‐TE₁₁₃ mode at 28.2 GHz. The dual‐band DRA is fabricated and measured. Due to the higher order mode, the average gain of the DRA in the upper band is about 3 dB higher than that in the lower band. The measured impedance bandwidths (|S₁₁| < ?10 dB) are 17.0% (20.5‐24.3 GHz) and 15.2% (26.1‐30.4 GHz), while the measured axial ratio (AR) bandwidths (AR < 3 dB) are 12.8% (21.2‐24.1 GHz) and 5% (27.4‐28.8 GHz). In addition, the peak gain values are 5 and 8 dBic.     

Stacked rectangular dielectric resonator antenna with different volumes for wideband circular polarization coupled with step‐shaped conformal strip

This paper presents a wideband circularly polarized broadside radiation characteristics by using stacked rectangular dielectric resonator antenna (DRA) with different volumes. In this designed antenna, the wide input impedance‐ and axial ratio (AR)‐bandwidths come from three factors: stacked rectangular DR with different volumes, stepped‐shaped conformal strip associated with microstrip line as a feed and different type of partial ground plane. Here, the orthogonal TE^x_δ11 and TE^y_1δ1 modes have been responsible for the generation of CP radiation in stacked rectangular DRA. Measured results show that the proposed stacked rectangular DRA with different volumes achieves input impedance bandwidth of 54.84% while AR bandwidth has been found to be 11.53%. The proposed antenna provides broadside right‐handed CP radiation pattern with gain ranges from 2.27–5.80 dBic and offers an average radiation efficiency of 89.48%, across the entire working bandwidth, respectively. Therefore, this antenna is very much useful for the ISM 2400 band applications.     

Tri‐band and quad‐band dual L‐slot coupled circularly polarized dielectric resonator antennas

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.     

A dual‐band circularly polarized antenna with aid of dual cylindrical dielectric resonator blocks

In this communication, a dielectric resonator based circularly polarized antenna is designed and investigated. A modified aperture is used to excite dual cylindrical dielectric resonator (CDR) blocks. Two important characteristics of the proposed radiator that makes it all the more attractive are as follows: (i) excitation of dual radiating modes that is, HEM_11δ and TE_01δ mode in cylindrical DR along with the support of dual‐band circularly polarized (CP) waves; (ii) arrangements of dual CDR blocks to reduce the Q‐factor which is useful to enhance the impedance bandwidth of both frequency bands. Fabrication as well as experimental measurement of the antenna prototype has been done for verifying simulation outcomes. This antenna design operates over dual frequency bands, that is, 5.01‐6.41 GHz and 7.3‐7.9 GHz with the fractional bandwidth of 24.73% and 9.39%, respectively. It supports CP waves over the frequency range 6.1‐6.5 GHz and 7.4‐7.8 GHz. The proposed antenna backs right‐hand circularly polarized (RHCP) radiation with an average gain of 4.5 dBi. These characteristics make it well fitted for WLAN, WiMAX (5.2/5.5/5.8 GHz), and downlink defense purpose satellite communication (7.2‐7.7 GHz).     

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).     

Miniaturized dual‐band dielectric resonator antenna for IEEE 802.16d fixed WiMAX applications

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.     

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.     

A wideband circularly polarized slot antenna with antipodal strips for WLAN and C‐band applications

A single‐fed circularly polarized square shaped wide slot antenna with modified ground plane and microstrip feed has been presented. The field in the slot is perturbed by introducing an antipodal strips section attached with a microstrip line to produce circular polarization in a wide band of frequencies. The antipodal strip section consists of a group of four strips of unequal length and separation. The presence of asymmetric perturbations in the slot is mainly responsible for exciting two orthogonal modes in the slot having equal magnitude and 90° phase difference which results in circular polarization. A wide bandwidth of 3.3 GHz (4.4 GHz‐7.7 GHz) has been achieved for an axial ratio value AR < 3 dB with the minimum axial ratio value being 0.3 dB. The impedance bandwidth for |S₁₁| < ?10 dB ranges from 4.3 GHz to 8 GHz, and therefore covers most of the C‐band communication systems. The antenna exhibits stable radiation patterns throughout the circular polarization bandwidth with a gain around 6 dBi in entire operational bandwidth. A prototype of antenna was fabricated and measured. The antenna has a planar size 0.40λ₀ × 0.40λ₀ and thickness of 0.02λ₀ where λ₀ is the wavelength in free space at the lowest frequency. With its compact size and low profile, the antenna is a favorable choice for WLAN (5.15‐5.85 GHz) and a wide variety of C‐band wireless applications.     

A new modified CPW‐fed wideband circularly polarized half‐split cylindrical dielectric resonator antenna with different permittivity of two layers in radial direction

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 TM_11δ 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.     

Dual‐port MIMO dielectric resonator antenna for WLAN applications

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.