Dual‐band dual‐polarized hybrid aperture‐cylindrical dielectric resonator antenna for wireless applications

A dual‐band dual‐polarized hybrid aperture‐cylindrical dielectric resonator antenna (CDRA) is examined in this article. Inverted regular pentagon shaped aperture is not only used to launch two radiating hybrid modes (HEM_11δ and HEM_12δ mode) in CDRA but also act as a radiator. Out of two frequency bands, the lower frequency band is linearly polarized while upper frequency band is the combination of both circular and linear polarization. A circular polarization (CP) characteristic in upper frequency band is created by loading quarter annular stub with microstrip line. LHCP/RHCP can easily be controlled by alternating the position of quarter annular stub. It is operating over two frequency ranges i.e. 2.48‐2.98 GHz and 4.66‐5.88 GHz with the fractional bandwidth 18.31% and 23.14% respectively. Axial ratio bandwidth (3‐dB) is approximately 8.78% (4.9‐5.35 GHz) in upper frequency band. The proposed antenna design is suitable WiMAX (2.5/5.5 GHz) and WLAN (2.5/5.5 GHz) applications.     

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).     

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.     

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.     

Complementary meander‐line‐inspired dielectric resonator multiple‐input‐multiple‐output antenna for dual‐band applications

The communication presents a simple dielectric resonator (DR) multiple‐input‐multiple‐output (MIMO) dual‐band antenna. It utilizes two “I”‐shaped DR elements to construct an “I”‐shaped DR array antenna (IDRAA) for MIMO applications. The ground plane of the antenna is defected by two spiral complementary meander lines and two circular ground slots. In the configuration, two “I”‐shaped DR elements are placed with a separation of 0.098λ. The antenna covers dual‐band frequency spectra from 3.46 to 5.37 GHz (43.26%) and from 5.89 to 6.49 GHz (9.7%). It ensures the C‐band downlink (3.7‐4.2 GHz), uplink (5.925‐6.425 GHz), and WiMAX (5.15‐5.35 GHz) frequency bands. Each DR element is excited with a 50‐Ω microstrip line feed with aperture‐coupling mechanism. The antenna offers very high port isolation of around 18.5 and 20 dB in the lower band and upper band, respectively. The proposed structure is suitable to operate in the MIMO system because of its very nominal envelope correlation coefficient (<0.015) and high diversity gain (>9.8). The MIMO antenna provides very good mean effective gain value (±0.35 dB) and low channel capacity loss (<0.35 bit/s/Hz) throughout the entire operating bands. Simulated and measured results are in good agreement and they approve the suitability of the proposed IDRAA for C‐band uplink and downlink applications and WiMAX band applications.     

A new dual C‐shaped rectangular dielectric resonator based antenna for wideband circularly polarized radiation

This article presents a new dual C‐shaped rectangular dielectric resonator (DR) based antenna for generation of wideband circularly polarized (CP) radiation. The proposed antenna comprises of a pair of C‐shaped rectangular dielectric DR and a metal strip with a coaxial probe. By utilization of a metal strip at the side surface of C‐shaped rectangular DR, the wideband CP radiation is achieved from the proposed dielectric resonator antenna (DRA). Fundamental orthogonal modes (TE^x_δ11 and TE^y_1δ1) are excited using the rectangular DRA with a metal strip for the generation of CP fields. The proposed antenna with dual C‐shaped rectangular CP DRA provides the measured ?10 dB reflection coefficient bandwidth of 30.07% (3.22 GHz‐4.36 GHz) with measured 3‐dB axial ratio bandwidth of 14.81% (3.25 GHz‐3.77 GHz) at the boresight. The proposed antenna covers the useful Wi‐MAX band.     

Dual port aperture coupled MIMO cylindrical dielectric resonator antenna with high isolation for WiMAX application

In this article, a dual port aperture coupled MIMO cylindrical dielectric resonator antenna with enhanced isolation is proposed. Dual feeding techniques are used to excite dielectric resonator. These feeding structures are oriented in such a way so that they can produce orthogonal mode in the dielectric resonator. High isolation is observed by generating two orthogonal modes, that is, and in the dielectric resonator. The fractional bandwidth for port 1 and port 2 is 17.8% (3.1‐3.68 GHz) and 18.4% (3.1‐3.7 GHz), respectively, and isolation between the two ports exceeds ?25 dB within the required band. The proposed antenna is simulated, fabricated, and experimentally tested. Good agreements between measured and simulated results are observed. The various diversity performance parameters are also lie within their acceptable limits. Based on presented results, it can be concluded that the presented MIMO antenna is suitable for WiMAX (3.3‐3.6 GHz) applications.     

Hybrid two segments ring dielectric resonator antenna for ultrawideband application

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 TM_01δ mode to TE_01δ 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.     

Design approach for dual element hybrid MIMO antenna arrangement for wideband applications

This communication explains the designing of two‐port based hybrid radiator for multiple‐input‐multiple‐output (MIMO) applications. Hybrid radiator includes U‐shaped printed line and ring dielectric resonator antenna (ri‐DRA). Wideband characteristics have been achieved by exciting both the U‐shaped printed line along with ri‐DRA. The U‐shaped metallic line acts as a magnetic dipole and helps to excite fundamental hybrid mode (HE_11δ) in the ri‐DRA. Dual L‐shaped and a rectangular defect have been created in ground plane for achieving wideband isolation over the working frequency band. Optimized Scattering parameters and far‐field results are verified by fabricating and testing of antenna prototype. Experimental outcomes confirm that the proposed MIMO antenna gives wider impedance bandwidth (80%), improved port isolation (better than 18 dB), stable gain (~ 4 dB), and radiation pattern. Various MIMO performance factors are analyzed and instituted in the tolerable boundaries.     

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.     

Low profile four‐port super‐wideband multiple‐input‐multiple‐output antenna with triple band rejection characteristics

A quad‐port planar multiple‐input‐multiple‐output (MIMO) antenna possessing super‐wideband (SWB) operational features and triple‐band rejection characteristics is designed. The proposed MIMO configuration consists of four modified‐elliptical‐self‐complementary‐antenna (MESCA) elements, which are excited by tapered co‐planar waveguide (TCPW) feed lines. A radiator‐matched complementary slot is present in the ground conductor patch of each MESCA element. The proposed MIMO antenna exhibits a bandwidth ratio of 36:1 (|S₁₁| < ?10 dB; 0.97‐35 GHz). Further, a step‐like slit‐resonator is etched in the radiator to eliminate interferences at 3.5 GHz. A hexagonal shaped complementary split ring resonator (CSRR) is also loaded on the MESCA radiator to remove interferences at 5.5 and 8.5 GHz. The MIMO antenna is fabricated on FR‐4 substrate of size 63 × 63 mm² and experimental results are found in good agreement with the simulated results. The MIMO antenna exhibits inter‐element isolation >17 dB and envelope correlation coefficient (ECC) <0.01 at all the four ports.     

A high‐isolation dual‐polarized quad‐patch antenna fed by stacked substrate integrated waveguides for millimeter‐wave application

A high‐isolation dual‐polarized quad‐patch antenna fed by stacked substrate integrated waveguide (SIW) that is suitable for millimeter‐wave band is proposed in this paper. The antenna consists of a quad‐patch radiator, a two‐layer SIW feeding structure and two feeding ports for horizontal and vertical polarization. The two‐layer stacked SIW feeding structure achieves the high isolation between the two feeding ports (|S₂₁| ≤ ?45 dB). Based on the proposed element, a 1 × 4 antenna array with a simple series‐fed network is also designed and investigated. A prototype working at the frequency band from 38 to 40 GHz is fabricated and tested. The results indicate that the proposed antenna has good radiation performance at 38 GHz that covers future 5G applications.     

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).     

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.     

CSRR‐loaded T‐shaped MIMO antenna for 5G cellular networks and vehicular communications

This article proposes a multiple input multiple output (MIMO) antenna for 5G‐based vehicular communication applications. The designed MIMO antenna consist of two element iterated T‐shape antenna with defected ground structure (DGS) and split ring resonator. The antenna providing reflection coefficient S₁₁ s₁₁ ≤10 dB and bandwidth of 6.3 and 3.96 GHz over the frequency range of 26.83 to 33.13 GHz and 34.17 to 38.13 GHz, respectively. For the suitable future vehicular millimetric wave communications, this antenna achieved resonant frequencies at 28, 33, and 37 GHz. The designed antenna has achieved peak gain of 7.11 dB in operating band. It is fabricated on 12 x 25.4 x 0.8 mm³ Rogers RT duroid 5880 substrate with dielectric constant (ε_r) of 2.2. The antenna is placed on vehicle in virtual environmental using ANSYS SAVANT tool and the simulated results are showing good matching with the measured results of proposed MIMO antenna.     

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.     

Compact planar frequency reconfigurable multiple‐input‐multiple‐output antenna with pattern and polarization diversity characteristics for WiFi and WiMAX standards

A compact planar frequency reconfigurable dual‐band multiple‐input‐multiple‐output (MIMO) antenna with high isolation and pattern/polarization diversity characteristics is presented in this article for WiFi and WiMAX standards. The MIMO configuration incorporates two symmetrically placed identical antenna elements and covers overall size of 24 mm × 24 mm × 0.762 mm. Reconfiguration of each antenna element is achieved by using a PIN diode which allows antennas to switch from state‐1 (2.3‐2.4 GHz and 4.6‐5.5 GHz) to state‐2 (3.3‐3.5 GHz and 4.6‐5.5 GHz). In state‐1, the configuration offers isolation ≥18 dB and 20 dB in lower band (LB) and upper band (UB) respectively; whereas, in state‐2, isolation ≥21 dB and 20 dB in LB and UB respectively is achieved. The same decoupling circuit provides high isolation in dual‐band of two states, which makes overall size of the proposed design further compact. The antennas are characterized in terms of envelope correlation coefficient, radiation pattern, gain, and efficiency. From measured and simulated results, it is verified that the proposed frequency reconfigurable dual‐band multi‐standard MIMO antenna design shows desirable performance in both operating bands of each state and compact size of the design makes it suitable for small form factor devices used in future wireless communication systems.     

Compact four‐port MIMO antenna on slotted‐edge substrate with dual‐band rejection characteristics

A compact ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO) antenna with dual band elimination characteristics is presented. The proposed MIMO antenna is comprised of four identical elliptical shaped monopole radiators located orthogonally to each other. A second order Koch fractal geometry is applied on the edges of the ground planes of the radiating elements; to reduce the overall size of the MIMO antenna, without compromising the lower frequency response. Further, in order to eliminate the undesired resonant bands (3.5 and 5.5 GHz) from UWB, an elliptical complementary split ring resonator is introduced in the monopole radiator. For reducing inter‐element coupling in the proposed MIMO antenna, a different approach (of slotted edge substrate) is used, as a substitute of traditional decoupling stub/elements. In the entire operating band of 3 to 13.5 GHz, inter‐element isolation more than 22 dB and envelope correlation coefficient less than 0.008 are obtained. The measured parameters of the fabricated prototype antenna are found in good agreement with the simulated results.     

Compact dual‐band ring dielectric resonator antenna with moon‐shaped defected ground structure for WiMAX/WLAN applications

In this article, compact ring‐shaped dielectric resonator antenna (DRA) along with moon‐shaped defected ground structure (DGS) was studied. The proposed antenna was fed by microstrip line shifted from center position, which excited TE_01δ mode in ring DRA. Moon‐shaped DGS was acting as a radiator and also reduced the size of proposed antenna by an amount of 14.87% (lower frequency band) and 48.77% (upper frequency band). The proposed antenna was designed to resonate at two different frequencies namely 2.24 and 5.82 GHz with a fractional bandwidth of 30.17% and 22.14%, respectively. Based on optimized design parameters, archetype of antenna structure has been constructed and measured successfully, which shows good agreement with simulated ones. The proposed antenna design was suitable for WLAN (2.4/5.2/5.8 GHz); WiMAX (2.5/5.5 GHz); AMSAT (5.6/5.8 GHz); and WAVE (5.9 GHz) bands. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:503–511, 2016.     

Design and its state‐of‐the‐art of different shaped dielectric resonator antennas at millimeter‐wave frequency band

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 (ε_r1 = 4 and ε_r2 = 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.