Integrated circular polarized microstrip antenna with dual‐mode‐polarization insensitive characteristics

A dual‐mode circularly polarized compact antenna with integrated left‐hand and right‐hand circular polarization (LHCP and RHCP) is presented in this work. A multilayer arrangement of a square patch and square ring structure with an irregular transmission line is analyzed for dual‐band, dual‐CP operation. To realize dual mode propagation the proposed structure is excited using electromagnetic coupling technique. Succeeding proximity feeding with T‐stub match is analyzed, which conveys impedance bandwidth of 180 and 300 MHz within |S₁₁| < ?10 dB at 3.5 and 5.5 GHz. The designed CP elements is suitably arranged with feed line for generating two orthogonal polarization of equal amplitude and a 90° phase difference at both the resonant modes (TM₁₀ and TM₀₁). Alterable LHCP and RHCP performance is realized by altering the compensated position and peculiar angle. Having both LHCP and RHCP polarization this design shows polarization insensitive characteristic. Each LHCP and RHCP antenna element accomplished a 3‐dB AR of 70 and 120 MHz with a gain up to 6 dBi. With a low profile of 0.27λ₀ × 0.27λ₀ × 0.04λ₀, the CP antenna is fabricated, and the performance is validated through experimental analysis. With all the viable characteristics, the antenna is proposed for Wi‐MAX/WLAN communication.     

Double triangular monopole‐like antenna with reconfigurable single/dual‐wideband circular polarization

A polarization and frequency reconfigurable circularly polarized (CP) antenna is proposed based on a novel bilateral switching mechanism. Two triangular monopole antennas are connected to each other in an L‐shaped form by a narrow link to produce a CP operation. In the proposed technique, 4 PIN‐diode‐based switches are designed with desired insertion loss and isolation, and only 2 DC‐voltage controllers. These switches are located on the links and the feed lines to realize a polarization reconfigurable feature including both right‐hand CP (RHCP) and left‐hand CP (LHCP) modes. Moreover, 2 CP states, a single wideband operation and a dual‐band operation, can be supported by this mechanism. In a special performance of the switches, CP reconfigurability can be obtained in a narrow‐band mode around 2.45 GHz. Two general simulations are performed based on the simple microstrip links and a diode‐circuit model. The measured results exhibit a wide overlapped bandwidth (AR < 3 dB and VSWR < 2) of 44.4% (1.63–2.56 GHz) with a peak gain of 2.88 dBi in the first state and 5.5% (1.22～1.29GHz) and 20.6% (2.12–2.61 GHz) with the peak gains of 0.52 and 3.0 dBi in the second state, respectively. A wide beamwidth is obtained more than 75°. This work is appropriate for L‐ and S‐band CP diversity applications.     

Dual‐band dual‐sense circularly polarized antenna based on crossed dipole structure for WLAN/WiMAX applications

This paper presents a new approach to design dual‐band antenna with dual‐sense circularly polarized (CP) operation. A principle for CP radiation is the use of two orthogonal dipoles and properly choosing their lengths can produce either right‐hand CP (RHCP) or left‐hand CP (LHCP) operation. In the proposed structure, the lower frequency band at 2.4 GHz is designed with RHCP radiation and LHCP is the operating mode of the higher band at 3.5 GHz. For verification, an antenna prototype is fabricated and measured. Measured data indicate that good performances over the RHCP and LHCP bands can be obtained with usable bandwidths of 2.9% (2.36‐2.43 GHz) and 1.7% (3.48‐3.54 GHz). Along with this, it also observes good unidirectional radiation patterns and the measured broadside gains are around 7.7 and 7.4 dBic across these frequency ranges.     

Frequency tunable circularly polarized antenna with branch line coupler feed network for wireless applications

In this article, frequency tuning and circularly polarized concentric circular microstrip antenna is investigated. The proposed antenna consist of varactor diode for frequency tuning and branch line coupler (BLC) feed network to achieve the circular polarization (RHCP/LHCP). By changing the varactor diode capacitance between 12.33 pF (0 V) to 1.30 pF (15 V) attain the frequency tuning (2.34‐2.68 GHz). The right hand circular polarization (RHCP) and left hand circular polarizations (LHCP) are realized in the antenna through BLC feed network output ports. The impedance bandwidth (2.05‐3.13 GHz) of BLC feed network is well‐matched with the circular microstrip antenna frequency tunable bandwidth. The proposed antenna is fabricated, and simulated results are verified using the mathematical modeling and experimental verification.     

Annular ring slot antenna design with reconfigurable polarization

A microstrip‐fed conventional annular ring slot (ARS) antenna with linear polarization (LP) is initially studied. To generate two orthogonal degenerate modes for circular polarization (CP) radiations, two identical meandering perturbation slots (MPS) are symmetrically loaded into the ARS. By further incorporating a PIN diode switch across each MPS, the proposed antenna can switch between left‐hand CP (LHCP), right‐hand CP (RHCP), and LP. All three polarizations have shown good impedance bandwidth and broad CP bandwidth that can satisfy the wireless local area network (WLAN) 2.4‐GHz operating band (2400–2480 MHz). Furthermore, desirable gains of 1.8–2.0 dBi and 2.40–2.84 dBic are also exhibited at LP and LHCP/RHCP, respectively. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:110–120, 2016.     

A low‐profile antenna with circularly polarized reconfigurable and omnidirectional radiation patterns

A low profile circularly polarized (CP) antenna with reconfigurable polarization is designed and presented, which can radiate omnidirectional patterns that can be switched between left‐hand circularly polarized (LHCP) and right‐hand circularly polarized (RHCP). A pair of arc‐shaped complementary dipoles is acted as reconfigurable elements by bridging four pin diodes at the dipole arced arms. A meander phase shift line is employed to connected the arc dipole arms and plate cavity to adjust the phase relationship of two sources. The proposed antenna exhibits the omnidirectional radiation pattern by combining six identical elements placed in a circular array configuration. 24 p‐i‐n diodes are exploited to six elements, by manipulating the dc bias voltage across the diodes, the polarization state of the antenna can be switched. The patterns of the antenna are similar to that of a dipole, but its size is only about Φ0.87 × 0.029λ₀ at 5.8 GHz. The overlapped bandwidth of measured 3‐dB axial ratio (AR) and 10‐dB return loss is 5.724‐5.87 and 5.738‐5.91 GHz for two polarization states, which are right on the target of ISM band. It can be well adapted to medical diagnosis systems.     

Design and implementation of a low profile polarization‐reconfigurable transmitarray with linear polarized feed

A novel polarization‐reconfigurable transmitarray with linear polarized feed is presented in this letter. Each element in the proposed transmitarray consists of two cascaded cross dipoles to achieve more than 310° of linear phase with transmission magnitude equal to or better than 0.8 dB. The proposed unit cell has a thickness of 0.22λ₀, which leads to a low profile transmitarray compared with those conventional designs. The element behavior of low transmission loss has resulted in higher antenna efficiency. By properly rotating the feed antenna around the center and selecting the x‐ and y‐dimension of each element, the proposed transmitarray can generate radiation patterns with different polarization states, including left‐handed circular polarization (LHCP), right‐handed circular polarization (RHCP), and linear polarization(LP). For the purpose of validation, a double‐layer center‐fed 11 × 11‐element transmitarray prototype is manufactured and tested at X‐band. Measurement results demonstrate the designed transmitarray realize both high gain performance and multiple polarization operation.     

Wideband polarization reconfigurable circularly polarized antenna with omnidirectional radiation pattern

This paper presents a wideband reconfigurable circularly polarized (CP) antenna with omnidirectional radiation pattern. The antenna is based on a shorted monopolar patch surrounded by multiple curved branches and it is proximity‐fed by a disk‐loaded coaxial cable. The polarization reconfigurability is realized by introducing PIN diodes on junctions between the patch and the branches to alter the current direction flowing on the branches. By properly controlling the ON/OFF states of the diodes, the antenna's polarization can be switched between right‐hand circular polarization (RHCP) and left‐hand circular polarization (LHCP). A reconfigurable prototype has been fabricated and measured. The experiments show that the prototype has wide overlapped bandwidth from 2.3 to 3.1 GHz, in which the reflection coefficient and the axial ratio (AR) are less than ?10 dB and 3 dB for both polarization states. Besides, the antenna radiates dipole‐like patterns with the realized gain of around 0.6 dBic across this operating band.     

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.     

Circularly polarized rectangular DRA coupled through orthogonal slot excited with microstrip circular ring feeding structure for Wi‐MAX applications

In this article, a wideband circularly polarized rectangular dielectric resonator antenna (RDRA) coupled through orthogonal slots and excited with a new microstrip circular ring has been investigated. Circular polarization has been achieved by using plus shaped (+) slot on the ground plane and excited through a new microstrip circular ring feed. TE_11δ mode has been excited in the RDRA which has been confirmed through the distribution of E ‐field and dielectric waveguide model (DWM) method of RDRA. Circularly polarized (CP) RDRA offering measured ?10 dB input impedance bandwidth of 20.79% (centered at 3.27 GHz) and 3 dB axial ratio bandwidth in broadside direction of 12.09% (centered at 3.39 GHz), respectively. From the CP radiation pattern, proposed design confirms that right ‐ handed CP (RHCP) in broadside direction. The difference between RHCP field and left ‐ handed CP (LHCP) field are above ?26 dB in operational band. In addition, the proposed CP antenna offers stable gain and radiation efficiency in working bands and it is suitable for IEEE 802.16e/d Wi‐MAX (3.3‐3.7 GHz) band.     

Substrate integrated waveguide dual‐frequency dual‐sense circularly polarized cavity‐backed slot antenna

A novel design of dual‐frequency dual‐sense circularly polarized (CP) substrate integrated waveguide (SIW) cavity‐backed slot antenna is presented for dual‐band wireless communication systems. The proposed antenna consists of square SIW cavity, asymmetrical bow‐tie‐shaped cross slot and probe feed. Due to use of asymmetrical bow‐tie‐shaped cross slot, circularly polarized wave radiates at two different frequencies with opposite sense of polarizations. The RHCP radiation occurs at (10.45‐10.54) GHz (Lower band) and LHCP occurs at (11.26‐11.34) GHz (Upper band). Moreover, in each band, sense of polarization can be change by changing the feed position. The front to back radiation ratio (FTBRR) is more than 10.5 dB and cross polarization level is lower than ?20 dB in both the bands.     

Single layer CPSSA array with change polarization diversity in broadband application

The present study proposes a novel broadband circularly polarized (CP) multiple‐input multiple‐output antenna array designed for C‐band applications. The first step was the introduction of a reconfigurable circularly polarized square slot antenna (CPSSA) capable of changing polarization diversity, which could cover impedance bandwidth (BW) from 4.48 to 8.21 GHz with 1.9 GHz of ?3 dB axial ratio (AR) BW. Then, a feed network composed of 90° and 180° couplers, a crossover, and delay lines was presented. The CPSSA with two metalized via‐holes adopted with two ports polarization diversity fed the networks. A number of reconfigurable CP array antennas using the polarization diversity technique have been presented so far. However, given that the proposed layout designed in a single layer had advantages of reduced antenna size and increased antenna gain and ARBW, this approach has received due attention over recent years. Another promising feature of this approach is its capability to change the polarization diversity by rotation of phases in the array feed network using PIN diodes.     

Wideband circularly polarized dielectric resonator antenna coupled with meandered‐line inductor for ISM/WLAN applications

A new meandered‐line inductor fed wideband circularly polarized rectangular dielectric resonator antenna (DRA) with partial ground plane has been developed in this work. Meandered‐line inductor feed and partial ground plane are used for generation of orthogonal modes, hence circular polarization (CP) in DRA. By controlling the length of meandered‐line inductor, three different CP DRA have been designed for different wireless applications such as Wi‐MAX and WLAN/ISM 2400 band. Distribution of electric field inside rectangular DRA shows that all three antenna having TE_11δ mode. Finally, a lower frequency band application at 2.4 GHz (ISM) called here as Proposed Antenna, has been considered for fabrication. This designed antenna shows measured ?10 dB input impedance bandwidth of 20.67% and 3‐dB axial ratio bandwidth of 27.95% in broadside direction. All these three CP antennas (Antenna‐1 to Proposed Antenna) are showing stable gain and right hand circular polarization in broadside direction.     

Tilted bi‐sense circularly‐polarized antenna and its application for radio frequency identification system

A tilted bi‐sense circularly polarized (CP) antenna and its application for UHF radio frequency identification (RFID) system is proposed. A planar concial monopole working as the electric dipole is designed at first. When a shorting pin is added, a loop radiator would be generated, and thus a pair of orthogonally oriented complementary dipoles is realized. In this way, both right‐handed circularly polarized (RHCP) and left‐handed circularly polarized waves (LHCP) are generated simultaneously in tilted directions within one hemisphere. Then, closed‐form formulas are derived to reveal the tunability mechanism of bi‐sense property and provide a design guideline for system application. It is demonstrated that flare angle of conical monopole has a linear relationship and sine function to CP beam direction and 3‐dB axial ratio (AR) beamwidth, respectively. Finally, antenna prototypes are fabricated and tested for validation. It is also demonstrated that at the tilted direction of θ = ± 45°, a 3‐dB AR bandwidth of 4.9%, and gain up to 5 dB are realized. Comparing with conventional microstrip patch antenna, an enhanced reading range over 5 m can be obtained in the tilted range from 40° to 75° and ? 75° to ?40° in UHF RFID sytem application.     

Circularly polarized V‐shaped dielectric resonator antenna

In this article, a probe fed V‐shaped dielectric resonator antenna (DRA) loaded with circular patches, is proposed for X band applications. A prototype was fabricated to validate the results. Circular polarization is achieved by the geometry of DRA integrated with the circular patches on its surface. These circular patches behave as a monopole antenna. To achieve circular polarization two orthogonal fields have been excited in the DRA, which are in time phase quadrature. Due to the symmetry of design, it shows dual polarization, both Left Hand Circular Polarization (LHCP) and Right Hand Circular Polarization (RHCP), in two orthogonal directions. The fabricated prototype exhibits wide impedance bandwidth of 7.85‐10.1 GHz (25%) and circular polarization (CP) Bandwidth (BW) of 8.35‐8.7 GHz (4%). Maximum measured gain of 4.8 dBi has been obtained in comparison with the simulated gain of 5.6 dBi. Applications of the proposed antenna include satellite communication, telemetry tracking and control, Synthetic aperture radar (SAR), weather radar, and military radar in X band. Directional CP performance is useful in designing a smart antenna and multiple input multiple output (MIMO) antenna.     

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).     

Metasurface cavity antenna for broadband high‐gain circularly polarized radiation

The article presents a microstrip patch (MSA) fed high gain circularly polarized metasurface cavity (CP‐MSC) antenna using a planar progressively‐phased‐reflector and a transmissive linear to circular polarization conversion metascreen. The bottom metasurface reflector consists of a remodeled Jerusalem cross to obtain 2π reflection phase variation. Linear to circular polarization conversion is achieved by a hexagonal ring based meta‐element with high transmission and bellow 3 dB axial ratio from 9.5 to 10.5 GHz. Simulated and measured results of assembled CP‐MSC antenna with MSA are in good agreement. The gain of the proposed cavity antenna with 10 and 10.5 GHz MSA are 14.9 and 16.3 dBi, respectively. Below 3 dB AR throughout the operating band denotes significant circular polarization performance of the proposed antenna.     

A CPW‐fed band notched wideband circularly polarized ZOR antenna based on CRLH‐TL approach

This article presents design and analysis of three wide band zeroth‐order resonance antennas (antennas I, II, and III) using composite right and left‐handed transmission line (CRLH‐TL) approach. Coplanar waveguide technology, single layer via‐less structures are used to have the design flexibility. The bandwidth characteristics are analyzed by using lumped parameters of CRLH‐TL. By introducing a simple slot in the ground plane of antenna I both bandwidth enhancement and circularly polarization characteristics are achieved in antenna II. Another quarter wave L‐shaped slot has been introduced in the ground plane of antenna II to introduce a notch band in the frequency response of antenna III. Achieved measured 10 dB return loss bandwidth of antenna I and antenna II are 960 (3.3‐4.26 GHz) and 2890 MHz (2.77‐5.66 GHz), respectively. Antenna III offers measured 10 dB return loss bandwidth of 3220 MHz (2.32‐5.54 GHz) with a band notch from 2.39 to 2.99 GHz that isolates the 2.4 GHz WLAN and 3.5 GHz WiMAX band. Antenna II and antenna III have circular polarization property with measured axial ratio bandwidth of 440 MHz. The measured peak realized gain of antennas II and III is around 1.53‐2.9 dBi.     

Dual circularly polarized loop antenna using a pair of resonant even‐modes

Conceptual design of dual circularly polarized (CP) square loop antennas using a pair of resonant even‐modes for wireless sensor application is presented. A pair of even‐modes is simultaneously excited within a single, nonuniform square loop element and employed to realize a dual circular polarization characteristic. When the natural boundary conditions of the even‐modes and the feed lines are matched, respectively, a bidirectional dual CP loop antenna can be attained at first. Then, a unidirectional dual CP loop antenna is designed by introducing a simple metallic reflector. Both bidirectional and unidirectional designs exhibit dual CP performance with available operation bandwidth of 10.0% and 8.5%. The design approach is expected to get applications in dual CP antenna designs for wireless sensor systems.     

Design of a compact wideband CP metasurface antenna

In this article, a new compact metasurface circularly polarized (CP) antenna is presented, where the rotating 45° periodic ellipse patch is used to achieve polarization conversion from linearly polarized to CP. The meta‐surface is composed of 4 × 4 ellipse patches with 45° rotation, which are etched on the top layer of upper substrate. A slot ground plane and a coplanar waveguide structure are printed on both sides of bottom substrate, and the bottom substrate is directly connected to the upper substrate, which can make the antenna profile lower. As demonstrated in this article, the presented antennas have good characteristics of excellent 3‐dB axial ratio bandwidth of 17.4% (5.25‐6.25 GHz), and wide 10‐dB impedance bandwidth of 20.6% (5.0‐6.15 GHz).