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.     

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).     

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.     

Dielectric resonator based two‐port dual band antenna for MIMO applications

This article investigates a dual band multiple input multiple output (MIMO) cylindrical dielectric resonator antenna (cDRA) for WLAN and WiMAX applications. It consists of two symmetrical orthogonally placed radiators. Each radiator is excited through a narrow rectangular aperture with the help of a microstrip line. For higher mode excitation, the proposed structure uses dual segment DRA which apparently looks like stacked geometry. The aperture fed dielectric resonator works as a feed for upper cDRA to generate higher order mode. The presented radiator covers the band between 3.3‐3.8 GHz and 5‐5.7 GHz. The measured isolation is better than 20 dB in the desired band. The average gain and radiation efficiency achieved for the proposed antenna is 6.0 dBi and 85%, respectively at the operating frequency band. In the proposed geometry, broadside radiation patterns are achieved by exciting HEM_11δ and HEM_12δ modes in a stacked geometry. Different MIMO performance parameters (ECC, DG, MEG, and CCL) are also estimated and analyzed. The prototype of proposed antenna is fabricated and tested. The measured outcomes are in good accord with the simulated one.     

Dual‐band reconfigurable circularly polarized monopole antenna

A microstrip antenna with dual‐band reconfigurable circular polarization (CP) characteristics in Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) bands is presented in this article. The proposed antenna has a symmetrical U‐shaped slot with PIN diodes on the ground plane. The slotted ground generates a resonant mode for broad impedance‐band width, and excites contrary CP state at 2.45 GHz for WLAN and 3.4 GHz for WiMAX, respectively. Because switching the states of PIN diodes on the slot can redirect the current path, the CP state of the proposed antenna can be simply switched between the right‐handed CP and left‐handed CP. The proposed antenna has a low profile and a simple structure. Measured results of the fabricated antenna prototype are carried out to verify the simulation analysis. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:109–114, 2015.     

Compact triple‐band stacked monopole antenna for USB dongle applications

In this article, a novel compact triple‐band stacked monopole antenna for USB dongle applications is proposed. The antenna consists of an e‐shaped monopole connected directly to the feedline and a square patch‐shaped monopole at another layer connected to feedline by a metallic pin. The e‐shaped monopole is used to obtain WLAN band (2.4‐2.48 GHz) and WiMAX band (3.4‐3.69 GHz). On the other hand, square patch‐shaped monopole is introduced to get WLAN bands (5.15‐5.35 and 5.725‐5.825 GHz) and WiMAX band (5.25‐5.85 GHz). The antenna is compact with the dimension of 17 × 13 mm².     

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.     

Broadband circularly polarized printed falcate‐shaped monopole antenna

In this study, a simple broadband circularly polarized (CP) printed monopole antenna for S/C‐band applications is proposed. The CP antenna is composed of a falcate‐shaped monopole with a right‐angle trapezoid stub, then wide impedance and axial ratio (AR) bandwidths are achieved. By placing one rectangular split‐ring resonator above the stub for generating upper CP mode, both of impedance and CP performances are further improved. The proposed antenna is fabricated on a FR4 substrate and measured. The measured ?10‐dB impedance bandwidth is 107%, ranging from 2.4‐7.9 GHz, and the measured 3‐dB AR bandwidth is 94% (2.4‐6.6 GHz), covering the entire wireless local area network (WLAN) and WiMAX bands.     

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.     

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.     

Circularly polarized D‐shaped slot antenna for wireless applications

A multiband circularly polarized slot antenna for wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) applications is designed, studied, and fabricated. Using modified ground plane structure, circular polarized characteristics are realized. An open rectangular loop is introduced on the ground plane to generate orthogonal modes at middle resonance frequency. At higher resonance frequency to improve axial ratio bandwidth, a D‐shaped radiator is used. Thus, the cooperation of modified ground plane, open loop resonator, and D‐shaped radiator improves performance of the antenna at all the required bands. The proposed microstrip antenna generates separate impedance bandwidths to cover frequency bands of WLAN and WiMAX applications. The realized antenna is relatively small in size 40 × 54 mm² or 0.26_ × 0.36_ where _ is the free‐space wavelength at the desired first resonant frequency 2.0 GHz and operates over frequency ranges 26% (2.0‐2.6 GHz), 8.9% (3.21‐3.51 GHz), and 50.6% (3.8‐6.38 GHz). In addition, the antenna exhibits 5% (2.32‐2.44 GHz), 5.8% (3.3‐3.5 GHz), and 5.2% (5.61‐5.91 GHz) Circular Polarization bandwidth, making it suitable 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.     

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.     

A vertex‐fed hexa‐band frequency reconfigurable antenna for wireless applications

Present article embodies the design and analysis of an octagonal shaped split ring resonator based multiband antenna fed at vertex for wireless applications with frequency‐band reconfigurable characteristics. The proposed antenna is printed on FR4 substrate with electrical dimension of 0.4884 λ × 0.4329 λ × 0.0178 λ (44 × 39 × 1.6 mm³), at lower frequency of 3.33 GHz. The antenna consists of SRR based vertex fed octagonal ring as the radiation element and switchable reclined L‐shaped slotted ground plane. Antenna achieves six bands for wireless standards viz: upper WLAN (5.0/5.8 GHz), lower WiMAX (3.3 GHz), super extended C‐band (6.6 GHz), middle X band (9.9 GHz—for space communication), and lower K_U band (15.9 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The proposed design achieves hexa band characteristics during switching ON state of PIN diode located at reclined L‐shaped slot in the ground plane. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.     

Coplanar waveguide‐fed electrically small dual‐polarized short‐ended zeroth‐order resonating antenna using Ω‐shaped capacitor and single‐split ring resonator for GPS/WiMAX/WLAN/C‐band applications

This work explains the design and analysis of a triple‐band electrically small (ka = 0.56 < 1) zeroth‐order resonating (ZOR) antenna with wideband circular polarization (CP) characteristics. The antenna compactness is obtained due to ZOR frequency of composite right/left‐handed (CRLH) transmission line (TL) and wideband CP radiation are achieved due to the introduction of single‐split ring resonator and asymmetric coplanar waveguide fed ground plane. The proposed antenna obtains an overall electrical size including the ground plane of 0.124 λ₀ × 0.131 λ₀ × 0.005 λ₀ at 1.58 GHz and physical dimension of 23.7 × 25 × 1 mm³ are achieved. The antenna provides a size reduction of 44.95% compared to a conventional monopole antenna. The novelty behind the ohm‐shaped capacitor is the generation of extra miniaturization with better antenna compactness. The antenna provides dual‐polarized radiation pattern with linear polarization radiation at 1.58 and 3.54 GHz, wideband CP radiation at 5.8 GHz. The antenna measured results shows good impedance bandwidth of 5%, 6.21%, and 57.5% for the three bands centered at 1.58, 3.54, and 5.8 GHz with a wider axial ratio bandwidth (ARBW) of 25.47% is obtained in the third band. The antenna provides a higher level of compactness, wider ARBW, good radiation efficiency, and wider S₁₁ bandwidth. Hence, the proposed antenna is suitable for use in GPS L1 band (1.565‐1.585 GHz), WiMAX 3.5 GHz (3.4‐3.8 GHz) GHz, WLAN 5.2/5.8 GHz (5.15‐5.825 GHz), and C‐band (4‐8 GHz) wireless application systems.     

A metamaterial hepta‐band antenna for wireless applications with specific absorption rate reduction

Present article embodies the design and analysis of slotted circular shape metamaterial loaded multiband antenna for wireless applications with declination of SAR. The electrical dimension is 0.260 λ × 0.253 λ × 0.0059 λ (35 × 34 × 0.8 mm³) of proposed design, at lower frequency of 2.23 GHz. The antenna consists of circular shape rectangular slot as the radiation element loaded with metamaterial split ring resonator (SRR) and two parallel rectangular stubs, etched rectangular single complementary split‐ring resonator (CSRR) and reclined T‐shaped slot as ground plane. Antenna achieves hepta bands for wireless standards WLAN (2.4/5.0/5.8 GHz), WiMAX (3.5 GHz), radio frequency identification (RFID) services (3.0 GHz), Upper X band (11.8 GHz—for space communication) and Lower K_U band (13.1 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The SRR is responsible for creating an additional resonating mode for wireless application as well as provide the declination in SAR about 13.3%. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.     

A compact double‐layer wideband circularly polarized microstrip antenna with parasitic elements

In this article, a new broadband circularly polarized (CP) microstrip patch antenna (MPA) with a sequential phase (SP) square‐loop feeding structure is proposed. The presented antenna is composed of a square‐loop feeding structure, four L‐shaped parasitic patches with L‐shaped slots, four parasitic square patches, and a corner‐truncated square patch. At first, a SP square‐loop is designed as a feeding structure. Then, four L‐shaped parasitic patches with L‐shaped slots are utilized to generate one CP mode by a capacitive coupled way. At last, four parasitic square patches and a corner‐truncated square patch are together placed above the SP feeding structure to broaden the circularly polarized bandwidth (CPBW). The presented antenna has a wide 3‐dB axial ratio bandwidth (ARBW) of 16.7% (5.4 GHz, 4.95‐5.85 GHz), and a wide 10‐dB return loss bandwidth of 25.5% (5.5 GHz, 4.8‐6.2 GHz). The proposed antenna features compact structure and broad 3‐AR bandwidth which could completely cover the WLAN (5.725‐5.85GHz) band. Therefore, the proposed antenna is suitable for circular polarization applications in C band.     

Design and development of enhanced bandwidth multi‐frequency slotted antenna for 4G‐LTE/WiMAX/WLAN and S/C/X‐band applications

A multi‐frequency rectangular slot antenna for 4G‐LTE/WiMAX/WLAN and S/C/X‐bands applications is presented. The proposed antenna is comprised of rectangular slot, a pair of E‐shaped stubs, and an inverted T‐shaped stub and excited using staircase feed line. These employed structures help to achieve multiband resonance at four different frequency bands. The proposed multiband slot antenna is simulated, fabricated and tested experimentally. The experimental results show that the antenna resonates at 2.24, 4.2, 5.25, and 9.3 GHz with impedance bandwidth of 640 MHz (2.17‐2.82 GHz) covering WiMAX (802.16e), Space to Earth communications, 4G‐LTE, IEEE 802.11b/g WLAN systems defined for S‐band applications. Also the proposed antenna exhibits bandwidth of 280 MHz (4.1‐4.38 GHz) for Aeronautical and Radio navigation applications, 80 MHz (4.2‐4.28 GHz) for uncoordinated indoor systems,1060 MHz (5.04‐6.1 GHz) for the IEEE 802.11a WLAN system defined for C‐band applications and 2380 MHz (7.9‐10.28 GHz) defined for X‐band applications. Further, the radiation patterns for the designed antenna are measured in anechoic chamber and are found to agree well with simulated results.     

Compact dual wide‐band four/eight elements MIMO antenna for WLAN applications

A compact four and eight elements multiple‐input‐multiple‐output (MIMO) antenna designed for WLAN applications is presented in this article. The antenna operates in IEEE 802.11b/g WLAN (2.4 GHz), IEEE 802.11 ac/n WLAN (5.2 and 5.8 GHz) and WiMAX (5.8 GHz) bands. The resonated mode of the antenna is achieved by two unequal Reverse‐L shaped, line‐shaped slots on top and parasitic element on the ground layer. The single antenna provides wide bandwidth of about 29% (2.3‐3.1 GHz) in lower and 22% (4.9‐6.1 GHz) in the upper band. The compactness of the single element antenna is found about 95% with respect to the patch and 61% in overall dimension. Thereafter an investigation is carried out to design two, four, and eight elements MIMO antennas. All of the multi‐element structures provide compact configuration and cover entire WLAN frequency ranges (2.4‐2.48 and 5.15‐5.85 GHz). The dimension of the proposed eight element MIMO antenna is 102 × 52 × 1.6 mm³. It covers the frequency (measured) from 2.4 to 3.1 GHz and 5 to 6.1 GHz. The diversity performance of the proposed MIMO antenna is also assessed in terms of the envelope correlation coefficient (ECC), diversity gain (DG), and total active reflection co‐efficient (TARC). The ECC is found <0.5 whereas the DG >9.0 is obtained for the desired bands.