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Summary: In today's intricate wireless communication environment, ensuring system quality demands the use of a reliable and versatile antenna system. This research article introduces a polarization reconfigurable antenna integrated with a 4 × 4 Artificial Magnetic Conductor (AMC) surface. The AMC unit cell exhibits a triple‐band reflection phase response at 1.8GHz, 4.5GHz, and 5.5GHz, demonstrating double negative metamaterial behavior. The antenna features two distinct C‐shaped metal strips connected to two PIN diodes, enabling dynamic current distribution adjustment. Consequently, the proposed antenna offers three reconfigurable states, facilitating seamless switching between dual circular polarization (left and right‐hand circular polarization) and linear polarization. With a frequency coverage ranging from 1.29 to 2.52GHz and 3.59 to 6.15GHz, the antenna boasts a maximum axial ratio (AR) bandwidth of 31.96%. Additionally, it achieves a maximum peak gain of 5.5 dB and maintains front‐to‐back ratio (FBR) values exceeding 25 dB, while recording a minimum specific absorption rate (SAR) value of 0.1059 W/kg. The integration of the AMC surface ensures enhanced performance of the antenna. Experimental results from constructed prototypes closely align with simulation outcomes, validating the effectiveness of the proposed antenna. Consequently, this antenna holds significant promise for next‐generation wireless applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A monopole antenna with dual (linear/circular) polarization reconfigurability for X-band applications is presented in this paper. The antenna consists of a bent arm cross-shaped (BACS) slot created on the inverted triangular staircase fractal (ITSF) shaped patch. Two PIN diodes are embedded on the opposite side of the horizontal arm of the BACS slot for electronic switching between two different polarization states. By varying the biasing conditions of PIN diodes, the measured antenna’s 3 dB axial ratio (AR) operational band for left-hand circular polarization (LHCP) is observed from 9.88 GHz to 11.06 GHz, whereas linear polarization (LP) is achieved from 7.95 GHz to 12.64 GHz. The measured peak gain of the antenna is 5.71 dBi, whereas the average peak gain is obtained as 4.97 dBi. The size of the antenna is $1.57\mathrm {\lambda }_{\mathrm {g}}\times 1.25\mathrm {\lambda }_{\mathrm {g}}$ where, $\mathrm {\lambda }_{\mathrm {g}}$ is guided wavelength at the lowest cutoff frequency, 7.95 GHz. The proposed monopole antenna’s progressive design steps, an equivalent lumped circuit model analysis, and a comparative study between electromagnetic (EM) simulation and measured results are carried out to validate the antenna’s performance.

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polarization reconfigurable antennas at millimeter-wave (mm-wave) frequencies are important technologies for 5G and beyond wireless communications systems. This article presents an mm-wave multi-linear polarization (LP) reconfigurable antenna. It employs a resonant TM510-mode air-filled cavity as the base, and a circular array of slots is uniformly etched on its top surface to provide a rotationally symmetrical “excitation” for the multi-LP antenna. An upper substrate printed with engineered patch layers is introduced above the slots for an in-phase high-gain composition, and it is mechanically rotated to facilitate the multi-LP reconfiguration. Each slot radiation is separately monitored and analyzed by using single-slot cavity models. A final multi-LP antenna that can switch among five LP states at mm-wave band was constructed. To overcome the classic high sidelobe problem associated with circular arrays, a modified bottom layer is introduced to the multi-LP antenna. The measured overlapped bandwidth of the optimized multi-LP antenna ranges from 28.58 to 28.99 GHz. For all of the five LP states, the simulated and measured sidelobe levels are −13 and −10 dB, respectively. The measured realized gains are varied from 15.5 to 16.8 dBi in the overlapped operating bandwidth. This is the first time to report an mm-wave multi-LP reconfigurable antenna. [ABSTRACT FROM AUTHOR]

In this article, a novel polarization‐reconfigurable antenna based on the theory of linearly polarized (LP) modes combination is proposed. The antenna can electronically alter its polarization states between left‐hand circular polarization, right‐hand circular polarization and continuous linear polarization. A corner‐truncated square patch with two isolated aperture‐coupling feeds is used as the main radiator. By independently exciting the two feeding ports, the proposed antenna can work in two isolated orthogonal LP modes at 2.45 GHz, respectively. By simultaneously exciting the two feeding ports with different combination of amplitudes and phases, two circularly polarized (CP) modes and LP modes polarized at arbitrary azimuth can be obtained. The simulated and measured gains for all the polarization states are 7.3 dB at 2.5 GHz. The –10 dB impedance bandwidth ranging from 2.35 to 2.58 GHz is fully overlapped for all the polarization states. [ABSTRACT FROM AUTHOR]

A circularly-polarized-reconfigurable patch antenna based on fluidic control method is proposed in this paper. A liquid dielectric, ethyl acetate, is introduced to change the substrate of a patch antenna from homogeneous to inhomogeneous. Two orthogonal fundamental transverse magnetic (TM) modes are excited with a 90° phase difference in order to produce circularly polarized (CP) radiation. Then, the polarization of the proposed patch antenna is switchable between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) through the injection of the liquid dielectric to different channels in the substrate. For demonstration, the proposed antenna is designed at 2.4 GHz for radio frequency identification (RFID) application. According to the measured result, the proposed circular-polarization-reconfigurable patch antenna has a stable circularly polarized (CP) gain of 8 dBic and an efficiency of 90 % across the effective frequency band. Additionally, the measured overlapped impedance bandwidth of two polarization state is from 2.24 to 2.52 GHz which can fully cover the measured overlapped 3-dB axial ratio (AR) bandwidth from 2.38 to 2.43 GHz.

This paper presents a novel polarization-reconfigurable antenna based on the combination of circularly polarized (CP) modes, which is capable of changing its polarization states among arbitrary linear polarizations (LPs), left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). A truncated square patch with two isolated aperture-coupling feeds is used as radiation element operating at 2.45 GHz, which can operate in two orthogonal CP modes with low crosstalk. By exciting one of the two feeding microstrip lines, LHCP or RHCP mode can be independently generated. Meanwhile, by simultaneously exciting the two feeding microstrip lines with identical amplitudes but with different initial phases, LP mode with polarization plane oriented in any desired azimuth direction can be obtained. The simulated and measured peak gain of the proposed antenna remains at about 6.8 dBi at 2.45 GHz and the impedance matching bandwidth ranging from 2.25 to 2.60 GHz is fully overlapped for all the polarization states. Experimental results show a good performance of the proposed antenna.

A design for reconfigurable circularly polarized (CP) microstrip antennas with frequency agility is described. The main radiating element of the antenna is a suspended patch, and it is connected with two vertical feed probes. When one feed probe is used as a signal input port, the other probe can serve as a perturbation element of the microstrip antenna resonant at the fundamental mode, and consequently a CP radiation is generated. Because the dual probes are arranged in an orthogonal fashion, the antenna can be operated in right‐handed and left‐handed circular polarization modes. To vary the CP operation frequency, four varactors are mounted on the ring slot embedded on the radiating patch. Simulated results indicate that the CP frequency can be continuously tuned from 1.2 to 1.9 GHz with decreasing the capacitance of the varactors. A prototype is also fabricated, and only one DC bias is required to realize the reconfigurable antenna. The design concept of the proposed antenna is shown, and CP performances at different frequencies are also presented. [ABSTRACT FROM AUTHOR]

A combined frequency and polarization reconfigurable textile based wearable disc monopole antenna is proposed in this paper. The antenna consists of a disc monopole as the radiator and four PIN diodes for realizing the agility property. By varying the different switching combination of the PIN diodes, frequency reconfigurability is achieved between the GSM and ISM band. Two circular polarization states, right hand circular polarization (RHCP) and left hand circular polarization (LHCP) are also realized in each operating frequency band. The upper band polarization state is controlled by a L shaped stub introduced in the ground plane whereas the lower band polarization agility depends on the length of the parasitic arc placed around the main radiator. The antenna is fabricated and its performance is measured to validate the proposed design.

In this paper, a penta-polarization reconfigurable antenna with mushroom-type metamaterial loading is proposed, which can operate in x-direction linear polarization (x-LP), y-LP, 45°-LP, left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). In order to realize polarization reconfigurability, a dual-port dual LP mushroom antenna excited by crossed H-shape slot is designed by characteristic mode analysis (CMA). Through shifting the states of PIN diodes on the reconfigurable feeding network, the amplitude and phase distributions of two ports of the dual LP antenna can be dynamically controlled and the five polarization modes can be achieved. A prototype with a profile of 0.06λ0 at 5.2 GHz (λ0 is the operated wavelength in free space) is simulated and measured. The measurement results exhibit a wide impedance bandwidth over 33.2% for LPs and over 38.7% for CPs. In addition, the measured axial ratio bandwidths are 28.0% for LHCP and 30.3% for RHCP, and the maximum measured boresight gains of all modes are higher than 8.2 dBi. The simulated and measured results verify that the proposed antenna can achieve a balance between low-profile and broadband on the basis of penta-polarization reconfigurability. The proposed antenna can be applied to polarization diversity and C band satellite communication.

A compact antenna with tri‐polarization switching is presented. The antenna is mainly composed of a monopole slot and a shorted loop, and the two radiating elements are connected in series and placed in a metallic box filled with dielectrics. To realize polarization switching, four PIN diodes are introduced into the antenna structure, and they cannot only suppress the excitation of the loop antenna but also vary the direction of the current flowing on the loop. Both simulated and measured results indicate that the proposed antenna can be operated in one linear polarization and dual circular polarization modes within an impedance bandwidth of around 15%; moreover, the aperture size of the antenna is about 0.09 λ02. Based on the polarization reconfigurable antenna, a 1 × 8 phased array with an aperture size of 0.3 λ0 × 2.8 λ0 is then developed. Simulated results show that the phased array operating in each polarization mode can give a gain fluctuation of smaller than 1.5 dB and a side lobe level of less than −10 dB when the beam is scanned from −60° to 60°. Experiments are also carried out, and their results have good agreements with the simulated data. [ABSTRACT FROM AUTHOR]

In this article, designs of high gain polarization reconfigurable antenna arrays are proposed. A reconfigurable single‐layer polarization converter working in transmission mode is integrated with 1 × 4 and 2 × 2 patch array antennas to arrive at the design of polarization reconfigurable antennas. The antenna arrays with the polarization converter radiate linearly or circularly polarized waves depending on the bias state of PIN diodes used in the converter. LP wave is obtained if the diodes are forward biased while the reverse bias state of the diodes provides a circularly polarized wave. The 1 × 4 patch array integrated with the polarization converter exhibits an operating bandwidth of 6.12% (14.5‐15.4 GHz) with an average gain of 14.3 dB for the linear/circular polarization states. The operating bandwidth of 6.75% (14.3‐15.3 GHz) and an average gain of 12.6 dB are obtained for the 2 × 2 patch array with the converter. The prototypes of the antenna arrays with the polarization converter are fabricated and their performance characteristics are measured. The simulated and measured results are found to be in close agreement. [ABSTRACT FROM AUTHOR]

In this paper, a microstrip single feed circular radiating patch loaded with two parasitic stubs to achieve diversity for antenna polarization is presented. The primary antenna is a circular metallic patch with a rectangular slotted Defected Ground Structure (DGS) and it resonated at 5.5 GHz for Linear Polarization (LP). To achieve Left and Right Hand Circular Polarization (LHCP and RHCP) two-quarter wavelength metallic stubs are attached with a radiating patch through two PIN diodes. The antenna reconfigures its polarization states between LP, LHCP, and RHCP by diodes switching configurations. The proposed antenna is printed on a 0.8 mm thick RT/Duroid 5880 substrate and it provided satisfactory agreement between measured and simulated results. It has an impedance bandwidth of 5.23–5.75 GHz (9.45%) for S11 less than −10 dB and Axial Ratio Bandwidth (ARBW) for 3 dB is approximately 5.4%. [ABSTRACT FROM AUTHOR]

Based on characteristic mode theory (CMT), a quad-polarization reconfigurable antenna with suppressed cross polarization is proposed in this article. The proposed antenna is composed of the radiator, excitation units, and feeding network. A square conductive slab (SCS) is used as the main radiator, which is designed elaborately by characteristic mode analysis (CMA). Different modes of the radiator are stimulated selectively by four groups of balanced inductive exciters (BIEs) to realize horizontal polarization (HP), vertical polarization (VP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Two p-i-n diodes are embedded into the feeding network to switch the excitation states of the four groups of BIEs, thereby achieving quad-polarization reconfiguration. More importantly, a novel method exploiting the CMA is adopted for achieving low cross polarization. By means of introducing the orthogonal mode, the cross-polarization component of the fundamental mode can be canceled out by the co-polarization component of the orthogonal mode, which greatly reduces the cross polarization from −10 to −40 dB in the two principal planes. The measurement results demonstrate that the quad-polarization agility and a cross-polarization level around −30 dB under all polarization states are achieved simultaneously, verifying the functionality and reliability of the proposed method. [ABSTRACT FROM AUTHOR]

A 2 × 2 array with reconfigurable pattern and polarization is presented. The element of the array is a circularly polarized (CP) antenna, which is mainly composed of a monopole slot, a dipole, and a cylindrical copper tube. By manually moving the dipole arms, the element can be operated at right‐handed and left‐handed circular polarization states; besides, each CP element can be electrically rotated with a servo motor, whereby the phase of its radiated fields is varied with rotation angle. Based on such a mechanically reconfigurable element, the resultant array at each CP state can be operated in different radiation modes, including broadside mode, conical mode, and steerable beam mode. In addition, the array operated in the broadside mode can also provide a linearly polarized radiation with 360° polarization scanning. Simulations for typical radiation modes of the proposed array are performed, and they are validated with experiments. [ABSTRACT FROM AUTHOR]

A combined frequency and polarization reconfigurable textile based wearable disc monopole antenna is proposed in this paper. The antenna consists of a disc monopole as the radiator and four PIN diodes for realizing the agility property. By varying the different switching combination of the PIN diodes, frequency reconfigurability is achieved between the GSM and ISM band. Two circular polarization states, right hand circular polarization (RHCP) and left hand circular polarization (LHCP) are also realized in each operating frequency band. The upper band polarization state is controlled by an L shaped stub introduced in the ground plane whereas the lower band polarization agility depends on the length of the parasitic arc placed around the main radiator. The antenna is fabricated and its performance is measured to validate the proposed design. [ABSTRACT FROM AUTHOR]

This paper presents a low-profile wideband omnidirectional antenna with reconfigurable tri-polarization. The proposed antenna is composed of a center-fed circular patch part that generates vertically polarized electromagnetic (EM) waves and a bent-branch connected patch part at the bottom that generates horizontally polarized EM waves. By loading PIN diodes on the symmetrical curved branches, the directions of the current flows on the antenna can be controlled to achieve reconfiguration between left-hand circular polarization (LHCP), right-hand circular polarization (RHCP) and linear polarization (LP). Measurement results show that the overlap bandwidths of − 10-dB impedance and 3-dB axial ratio (AR) of the antenna are 10.87% (2.35–2.62 GHz) and 10.91% (2.34–2.61 GHz) for LHCP and RHCP modes, respectively. Under the LP mode, the − 10-dB impedance bandwidth is 13.44% (2.29–2.62 GHz). The peak gains of the antenna are 4.8 dBic, 4.7 dBic, and 4.9 dBi for the LHCP, RHCP, and LP modes, respectively. Measurement results agree well with the simulation results, verifying the effectiveness of the antenna. [ABSTRACT FROM AUTHOR]

A polarization and band reconfigurable cross-slot antenna for multiband applications is presented in this paper. The antenna consists of four p–i–n diodes embedded in the cross-shaped slot in a ground plane and excited by a microstrip feed line. The p–i–n diodes are placed in such a way that they produce multiple bands, with linearly and circularly polarized (CP) radiation. By switching the states of the p–i–n diodes, the sense of rotation of the electric field in CP radiation can be reconfigured. The proposed structure can be configured to produce two bands that radiate linearly polarized waves or three bands, where, two are linearly polarized and one is CP. The proposed design concepts are validated bythe CST studio suite as well as measurementsare carried out on fabricated prototypes. [ABSTRACT FROM AUTHOR]

This paper describes a novel helical antenna made of pure water. The water helical antenna is realized by replacing the metallic arm of a conventional helical antenna with a plastic tube of circular cross section filled with pure water. The axially symmetric TM01 mode is excited along the water arm and accounts for the wave propagation and radiation. Circular polarization (CP) is achieved by choosing a proper dimension of the water helix. The measured results show that the proposed water helical antenna has an overlapping impedance bandwidth ($\vert \text{S}_{11}\vert < -10$ dB) and an axial ratio (AR) bandwidth from 1.27 to 2.13 GHz, or 50.6% fractional bandwidth. A water helix antenna with polarization reconfigurability is also designed and demonstrated. The measured results show that the proposed helix antenna exhibits polarization-reconfigurable capability over a wide frequency band. [ABSTRACT FROM AUTHOR]

A design for quad‐polarization‐agile antenna is described. A multiport crossed dipole that can provide dual orthogonal linear polarizations is used as the radiating element of the design. When the crossed dipole is fed with a tunable power divider, the two linear polarization radiations can be simultaneously excited with same amplitudes and difference phases. The resultant polarization modes include ±45° linear polarizations, right‐handed circular polarization, and left‐handed circular polarization. The overlapped operation bandwidth of the four polarization modes is about 49%, and the antenna operating in each polarization mode has almost the same radiation patterns. These patterns are also stable against frequency. Moreover, the occupied area of the polarization reconfigurable antenna is about 0.43λ0 × 0.43λ0. [ABSTRACT FROM AUTHOR]

A linearly polarized (LP) wave with an arbitrary polarization plane is generated by combining left-handed circularly polarized (LHCP) and right-handed circularly polarized (RHCP) waves radiated from a dual-circularly polarized patch antenna. The polarization plane of the LP wave is continuously controlled by changing the phase difference between the LHCP and RHCP waves by using variable phase shifters composed of a quadrature hybrid and varactor diodes. Experimental results show that the polarization plane rotates continuously from −95° to 107° with a cross-polarization discrimination kept better than 22 dB in the boresight direction at 5.2 GHz. [ABSTRACT FROM AUTHOR]

A novel circular polarization (CP) reconfigurable antenna is proposed. The CP antenna consists of two folded off‐center‐driven dipoles. By switching four PIN diodes in the off‐center‐driven dipoles, the senses of CP can be changed between the left‐handed CP and the right‐handed CP. Two parasitic rectangular loops are added to the folded off‐center‐driven dipoles to improve the bandwidth. A T‐shaped microstrip probe line is used to feed the antenna. Experimental results show that the CP reconfigurable antenna achieves an impedance bandwidth of 31% (2.05–2.8 GHz) for return los >10 dB and a CP bandwidth of 16% (2.3–2.7 GHz) for axial ratio <3 dB. The measured gain of the CP reconfigurable antenna is about 7 dBi. Plain Language Summary: Polarization reconfigurable antenna technology has been proposed as a promising solution to the situation of crowded frequency spectrum nowadays. The polarization reconfigurable antenna can be reconfigured to feature more than one polarization characteristic in the same operation frequency; thus, frequency reuse is realized. Polarization reconfigurable antennas have been attracting lots of attention due to its unique features in enhancing the system capacity, increasing the transmission rate, and improving the stability and quality of communication. In this paper, a circular polarization reconfigurable antenna with a simple planar configuration is proposed, which may find wide applications in wireless and satellite systems. Key Points: A circular polarization reconfigurable antenna that consists of two folded off‐center‐driven dipoles is presentedOperating principle and experimental results of the circular polarization reconfigurable antenna is discussedThe CP reconfigurable antenna features a simple planar configuration and thus may find wide applications in wireless and satellite systems [ABSTRACT FROM AUTHOR]

This paper reports a novel polarization-reconfigurable antenna array based on the theory of mode combination (MC), which can electronically alter its polarization states between left-hand circular polarization (LCP) mode, right-hand circular polarization (RCP) mode, and two combined linear polarization (LP) modes. The array element is adopted as the L-probes fed circularly-polarized antenna reported by Luk et al. [1]. To verify the concept, a prototype of 2×2 antenna array is manufactured and tested. By properly exciting the feeding probes, four polarization modes can be switchable. Measurement results show that the proposed antenna has an overlapped −10 dB impedance bandwidth around 34 % for both CP modes and LP(2) mode, and an overlapped 3 dB axial-ratio bandwidth around 22.0 % of the CP modes. The average realized gains are around 12.4 dB for CP modes and LP(1) mode, which remain stable in the axial-ratio bandwidth. [ABSTRACT FROM AUTHOR]

In this paper, a Fabry–Pérot resonator antenna (FPRA) with a metamaterial-loaded cavity is presented. The proposed antenna preserves the simplicity from single resonant cavity and linearly polarized (LP) feed. A 3-D-printed all-dielectric metamaterial structure with hybrid locally periodic patterns is placed between the superstrate and the ground plane. The loaded metamaterial provides a new configuration for achieving self-generated circular polarization (CP) for the FPRA. Owing to the fact that the generation of CP relies solely on the anisotropy of the metamaterial, independent control of the axial ratio (AR) and directivity becomes possible, thus avoiding potential tradeoffs to be made between the AR bandwidth and the directivity increment. In addition, further polarization agility between CP and LP states can be obtained by employing different angular rotations of the metamaterial with respect to the feed antenna. The proposed concept is verified through a design example carried out at around 10 GHz showing an overlapped impedance and AR bandwidth of 6.7% (from 9.6 to 10.27 GHz). The design considerations are given with the help of performing the ray-tracing analysis. The agreement between the measurement and full-wave simulation justifies the validity. [ABSTRACT FROM AUTHOR]

A rectangular dielectric resonator antenna (DRA) with multiple polarization modes is proposed in this study. The antenna is fed by adjustable feed network composed by Wilkinson power divider and tunable phase shift elements. On this reconfigurable design, it can operate in left‐handed circular polarization, right‐handed circular polarization, and linear polarization (LP) modes. The 3‐dB axial ratio bandwidth of 30.2% for CP modes and impedance bandwidth of 33.3% for CP states are obtained. The maximum gains are 5.7 dBic and 6.34 dBi for CP and LP states. A prototype is built on the FR4 substrate with ideal switches and tested to validate the design. Simulated and measured results showed good agreement on the polarization reconfigurable performances of interest. The proposed DRA can be applied to modern wireless system with polarization diversity requirements. [ABSTRACT FROM AUTHOR]

In this paper, an electronically polarization reconfigurable circular patch antenna with fixed resonant frequency operating at Wireless Local Area Network (WLAN) frequency band (2.4-2.48 GHz) is presented. The structure of the proposed design consists of a circular patch as a radiating element fed by coaxial probe, cooperated with four equal-length slits etched on the edge along x-axis and y-axis. A total of four switches was used and embedded across the slits at specific locations, thus controlled the length of the slits. By activating and deactivating the switches (ON and OFF) across the slits, the current on the patch is changed, thus modifying the electric field and polarization of the antenna. Consequently, the polarization excited by the proposed antenna can be switched into three types, either linear polarization, left-hand circular polarization or right-hand circular polarization. This paper proposes a simple approach that able to switch the polarizations and excited at the same operating frequency. Simulated and measured results of ideal case (using copper strip switches) and real case (using PIN diode switches) are compared and presented to demonstrate the performance of the antenna.

Abstract In this paper, a polarization and frequency reconfigurable antenna with double layer metasurface, responsible for frequency and polarization reconfiguration respectively, is proposed. This antenna could operate in linear polarization in 4 GHz and circular polarization in 5 GHz band. By rotating the frequency reconfiguration metasurface, the linear polarization (LP) operating frequency can be continuously changed from 4 GHz to 4.35 GHz (8.4%) with circular polarization operating frequency around 5 GHz unchanged. Moreover, polarization of the whole antenna at 5 GHz can be reconfigured to linear polarization (LP), right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) by rotating polarization reconfiguration metasurface, the 3 dB axial ratio bandwidth is 5.0–5.2 GHz (4%). In all states, gain of the antenna achieves 5 dBi. [ABSTRACT FROM AUTHOR]

Abstract: A coplanar waveguide fed polarization reconfigurable monopole antenna is proposed in this letter. The proposed antenna consists of L‐shaped stubs placed on either side of a monopole, two p‐i‐n diodes and a slot in the ground plane. In the proposed antenna structure, the switching element is not directly connected to the feed line. Depending on the switching state of the p‐i‐n diodes, the antenna either radiates left/right circular polarization or linear polarization. To validate the proposed design, the antenna was fabricated and its performance was measured. Since the ground plane is electrically small, the effect of the cable and SMA connector on the performance of the antenna is also investigated. The measured impedance bandwidth is 66.78% (3.67 GHz to 7.35 GHz) and the axial ratio bandwidth is 13.62% (4.24‐4.86 GHz) for circular polarization and 23.61% (3.81‐4.83 GHz) impedance bandwidth for linear polarization. [ABSTRACT FROM AUTHOR]

A novel cuboid quadrifilar helical antenna (QHA) with polarization and pattern reconfigurabilities is presented. The proposed antenna consists of a reconfigurable radiator and a switchable feeding network. The radiator combines two individual QHAs in a cuboid, which can be alternatively activated. The feeding network provides switchable quadrature excitations to the radiator. By controlling the p-i-n diodes on the radiator and the feeding network, four working states including both polarization and pattern agilities are achieved. The polarization of the antenna can be switched between two orthogonal circular polarizations, and the radiation pattern can be changed between broadside and backfire modes. A prototype designed to operate at 0.9 GHz band is developed and measured. The measured results validated that the antenna achieved the four working states with stable wide-beam radiation patterns. Moreover, the proposed antenna obtained wide impedance and axial-ratio bandwidths (36.2% and 22%, respectively) in a compact size ( $0.26\lambda _{0}\times 0.26\lambda _{0}\times 0.25\lambda _{0}$ ). The proposed antenna which has attractive electrical characteristics can be applied to various wireless communications, e.g., RFID readers, subway, and railway communications. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel multi-linear polarization (multi-LP) reconfigurable unidirectional circular patch antenna is proposed, which can switch among four LPs at every 45° rotation. The patch antenna is fed in the center and shorting posts are used to excite TM11 mode with LP. By controlling the connections between the four shorting posts and the ground plane using p-i-n diodes, four reconfigurable polarization states at \phi =0 ^\circ , \phi =45 ^\circ , \phi =90 ^\circ , or \phi =135 ^\circ can be realized. The size of this antenna is about $0.57\lambda \times 0.57\lambda \times 0.07\lambda $ at 2.45 GHz. It can be easily fabricated and has a simple biasing network. The measured overlapping impedance bandwidth for different polarizations under the condition |\text{S}11| \leq -10 dB is from 2.33 to 2.50 GHz, which agrees well with the simulated one. Moreover, the antenna maintains stable radiation patterns and the measured realized gains range from 5.3 to 5.9 dBi. [ABSTRACT FROM PUBLISHER]

A novel partially reflective surface (PRS) antenna is proposed, which can electronically alter its polarization between linear polarization, left-hand circular polarization (CP), and right-hand CP. The antenna consists of a shorted annular patch antenna as the source, a PRS structure to enhance the gain, and a reconfigurable Wilkinson power divider as the feed network. Four p-i-n diodes are inserted into each branch of the power divider to change its electrical length. By switching the p-i-n diodes ON and OFF, a phase difference of 0°, 90°, or −90° can be realized at the two output ports of the feed network, hence enabling the antenna to radiate either a linearly polarized signal or left/right-handed circularly polarized signal. A prototype antenna with the biasing network is designed, fabricated, and measured. Good agreement between the simulated and measured results is achieved. Measurement results show that the proposed antenna has an overlapped 10-dB impedance bandwidth and 3-dB axial-ratio bandwidth of 4.7–5.36 GHz (13.1%). The average realized gains are $\sim 9$ dBi/dBic, which remain reasonably stable for different polarizations. The proposed antenna outperforms most of the reported polarization reconfigurable antennas for its wide bandwidth and relatively high gain. [ABSTRACT FROM PUBLISHER]

In the paper, a singly fed circular patch antenna with polarization diversity is proposed, and its binary array for MIMO application is explored as well. The air substrate and aperture-coupled feed structure are adopted to increase bandwidth and simplify the bias circuit of PIN diodes. By controlling the states of four PIN diodes on the patch, the proposed antenna can produce linear polarization (LP), left- or right-hand circular polarization (LHCP or RHCP). For each polarization sense, the antenna exhibits wide impedance bandwidth, high gain and low cross-polarization. Two antennas are orthogonally placed to form a binary array for MIMO application, which has high isolation and low envelope correlation. The antenna and its array have advantages of simple biasing network, easy fabrication and adjustment, which can be widely applied in wireless communication systems. [ABSTRACT FROM AUTHOR]

A novel polarization-reconfigurable mechanism based on a polarization-rotation artificial magnetic conductor (PRAMC) structure is proposed. A new polarization-reconfigurable antenna is designed by combining a PRAMC-based multipolarized dipole antenna with a RFIC switch-based network, in which three polarization states of right-handed, left-handed circular polarization (RHCP, LHCP) and +45^\circ linear polarization (LP) can be realized by controlling the dc bias of the switches accordingly. The multipolarization antenna is well designed for offering three polarization states. A large 3-dB axial ratio (AR) bandwidth of 15.5%, a wide 3-dB AR beamwidth for CP states and a large cross-polarization isolation of more than 50 dB for LP state together with a broad impedance bandwidth of 20.5% are obtained. A switch network is used to generate three feeding modes, and the performance of the RF-integrated circuit (RFIC) switches is experimentally verified. A prototype of the proposed polarization-reconfigurable antenna is fabricated and tested. Good agreements between the measured and simulated results are observed, which indicates good performances of the proposed antenna. [ABSTRACT FROM PUBLISHER]

This communication introduces a polarization reconfigurable wideband circularly polarized (CP) antenna, which consists of four radiating arms connected to a reconfigurable feeding network. The four radiating arms excited by the feeding network are able to generate wideband CP waves with bidirectional radiation patterns in free space. In order to increase the gain and obtain a broadside radiation pattern, the proposed antenna is placed above a metallic reflector with the distance of quarter wavelength at the center frequency. In addition, polarization reconfigurability is realized by utilizing PIN diodes in the feeding transmission lines such that left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) modes can be selectively excited by controlling the on/off states of the PIN diodes. The proposed antenna exhibits a wide impedance bandwidth of 80% and an overlapped axial ratio (AR) bandwidth of 23.5% for both modes. The antenna gain is stable across the operating bandwidth with the peak gain of 4.8 dBic. The antenna has a wide AR beamwidth of 90°. The presented work is suitable for GPS, CNSS, or RFID applications. [ABSTRACT FROM PUBLISHER]

A polarization reconfigurable patch antenna with electric current disturbance is proposed in this paper. The proposed antenna mainly consists of a rhombus-shaped patch with a single feed, two conductive pads with a via hole, and two PIN diodes. The antenna can produce the linear polarization (LP), right-hand circular polarization (RHCP), and left-hand circular polarization (LHCP) by adjusting bias state of two PIN diodes. Besides, positions of the PIN diodes help that a bias circuit can be simply designed. The fabricated antenna provides a 10-dB bandwidth of 50 MHz in the two-off state of PIN diodes (LP, 2.635–2.685 GHz), 60 MHz in the two-on state of PIN diodes (LP, 2.625–2.685 GHz), 100 MHz in the RHCP and LHCP (2.57–2.67 GHz). Besides, it has −3 dB axial ratio bandwidth of 55 MHz in the circular polarization states. Details of the antenna design are shown, and the simulated and measured results for the constructed prototype are also presented and discussed. [ABSTRACT FROM AUTHOR]

This paper proposes a reconfigurable square-patch antenna with polarization diversity. The proposed antenna consists of a square radiating patch and a Y-shaped feed structure with two PIN diodes. The shape of the feed structure can be changed by adjusting the bias states of the two PIN diodes, which helps switch between two orthogonal linear polarizations. The polarization diversity characteristic is validated by the simulated current distribution and the measured radiation pattern. [ABSTRACT FROM AUTHOR]

This paper introduces a polarization reconfigurable wheel-shaped antenna with wide bandwidth and conical-beam radiation pattern. A wideband circular-monopolar patch surrounded by eight reconfigurable coupling loop stubs can generate conical-beam radiation patterns with different polarizations. This polarization reconfigurable characteristic is realized by controlling PIN diodes on the coupling loop stubs. The center-fed circular patch operates with the vertically-polarized conical-beam radiation and the coupling loop stubs radiate the horizontally-polarized wave propagation. With choosing proper magnitudes and phase differences between the two orthogonal radiations from the monopolar patch and the loop stubs, a circularly-polarized conical-beam radiation can be obtained. In addition, the presence of a back reflector yields a wide axial ratio bandwidth, enhances the front-to-back ratio of the radiation pattern, and avoids EM interferences between DC biasing lines and the antenna. This proposed antenna can generate three types of polarizations with the conical-beam radiation pattern including vertical polarization, left-handed circular polarization, and right-handed circular polarization by controlling the PIN diodes. Measured impedance and axial ratio bandwidths are 28.6% (3.45 to 4.6 GHz) and 15.4% (3.6 to 4.2 GHz), respectively, for the two CP modes. The maximum CP gain is 4.4 dBic. Furthermore, a dual-band operation (3.35 to 3.44 GHz and 4.5 to 4.75 GHz) can be observed for the LP mode. The antenna can operate at the downlink of standard C band (3.625 to 4.2 GHz) for geostationary satellite communication. [ABSTRACT FROM PUBLISHER]

A design of stacked square-ring patch antennas with quadri-polarization diversity is proposed. The polarization switching is realized with a 1-to-4 reconfigurable feeding network composed of a quasi-lumped coupler and PIN diodes. The size of the feeding network is less than 0.01\lambda0^{2}, where \lambda0 is the free-space wavelength of the operating frequency. In addition, by controlling dc voltages, the operation of the feeding network can be varied among four different modes. The performances of the stacked patch antenna and the reconfigurable feeding network are respectively exhibited. A prototype that integrates the feeding network into the inner slot of the lower square-ring patch of the stacked patch antenna is designed and constructed. The prototype can provide dual orthogonal linear polarizations and dual orthogonal circular polarizations at 1.98 GHz. Details of the experimental results for the prototype are shown. [ABSTRACT FROM PUBLISHER]

ABSTRACT In this article, we present a low profile polarization reconfigurable dipole antenna using a tunable electromagnetic band-gap (EBG) structure as ground plane. The EBG structure can be dynamically modulated by tuning the loaded PIN diodes through bias voltage circuit. The EBG-based antenna is fabricated and measured. Experimental results show that the tunable EBG structure can make the dipole antenna work at four states. For the state 1 and state 2, the emitted waves with left-hand and right-hand circular polarization are produced at 4.6 GHz, and the axial ratio is 1.2 and 0.3 dB, respectively. For the state 3 and state 4, the dipole antenna radiates the linearly polarized waves with the gains of about 6 dB at 4.6 and 4.25 GHz, respectively. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1281-285, 2014 [ABSTRACT FROM AUTHOR]

A four-element microstrip antenna array excited with a tunable feeding network is described.The feeding network is composed of three quasi-lumped couplers and a 90° phase delay line. By controlling one dc bias, the network can provide the same amplitude and two different phase combinations, including (0°, 0°, 180°, 180°) and (0°, 90°, 180, 270°), for the four array elements. With the tunable feeding network, the excitation method of the array can be switched between sequentially rotated feed mechanism and differential-feed mechanism. A reconfigurable array prototype is constructed. Experimental results show that the array has a broadside radiation and it can provide good linear and circular polarization performances at one frequency. Simulated results are also provided to validate the designs of the microstrip antenna array with switchable polarization. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1653-1657, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27660 [ABSTRACT FROM AUTHOR]

The performances of a quasilumped coupler with a pair of capacitors are first described. By varying the capacitance value of the capacitors, the coupler can operate at three different modes, including uncoupled-line mode, quadrature hybrid mode, and T-junction power divider mode. Based on the coupler design, a microstrip antenna with switchable polarization is developed and implemented. Experimental results demonstrate that the reconfigurable antenna can provide two linear polarizations and one circular polarization at one frequency. In addition, the antenna operating at each polarization state has good impedance matching and broadside radiation with low cross polarization. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:471-474, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27374 [ABSTRACT FROM AUTHOR]