Reconfigurable antenna feeding network for switchable circular and linear polarizations

In this paper, the reconfigurable annular ring slot antenna with circular polarization diversity is proposed for SDMB(satellite digital multimedia broadcasting) system. The proposed antenna consists of a ring slot with tuning stubs. Four PIN diodes are attached to achieve circular polarization diversity. By switching the diodes on or off, the proposed antenna can be operated either RHCP(right hand circular polarization) mode or LHCP(left hand circular polarization) mode. The experimental result shows that the proposed antenna has an impedance bandwidth( VSWR les 2 ) of 2.47~3.04 GHz(570 MHz) at LHCP mode, an impedance bandwidth( VSWR les 2 ) of 2.45~3.01GHz(560 MHz) at RHCP mode, a maximum gain of 3.1dBi at RHCP mode, 4.76dBi at LHCP mode. The 3dB CP bandwidth of about 100 MHz at both RHCP and LHCP mode is achieved at the center frequency 2.63 GHz. The proposed antenna is suitable for application such as mobile satellite communications, WLAN(wireless local area networks), and broadband wireless communication systems.

A novel single-feed design of a patch antenna with polarization reconfigurability is proposed in this paper. Four identical notches with parasitic elements are embedded into the design. The antenna can switch between linear polarization (LP), left hand circular polarization (LHCP) and right hand circular polarization (RHCP). The results show that the proposed antenna demonstrates an impedance bandwidth of 50 MHz (S11 <;-10 dB), and a polarization bandwidth of 44.3 MHz (axial ratio <; 3 dB). Also, the axial ratio is obtained in a broad angular range when the antenna is in LHCP and RHCP mode. The structure of the proposed antenna is simple and suitable for antenna array applications that require circular polarization and polarization diversity properties.

ABSTRACTIn this study, we propose a novel leaky wave antenna (LWA) based on half mode substrate integrated waveguide (HMSIW) technology etched on spoof surface plasmon polaritons (SSPPs) structure, which is able to switch the polarization property over four states with continuous scanning performance in the upper half space. The antenna is structured into two layers: the lower layer consists of two side‐to‐side HMSIWs, while the upper layer is composed of two sets of radiating elements. By changing the excitation ports, multiple polarization states—horizontal linear polarization (HLP), vertical linear polarization (VLP), right‐hand circular polarization (RHCP), and left‐hand circular polarization (LHCP)—are switchable in the same frequency range from the backward region to the forward region. To ensure continuous scanning property, the intrinsic open‐stopband (OSB) problem for HLP and VLP of LWA is solved by a set of metal vias in the lower layer and extra narrow metal‐stubs in the upper layer, respectively. The proposed antenna integrates multiple polarization in one set of frequency‐scanning antenna to satisfy the requirements of multi‐scenario application in the modern wireless communication system. The proposed antenna is manufactured and measured. Measured results reveal that the beams can scan from backward to forward under four polarizations, which verifies the correctness of design theory and simulation result.

In this article, a circular microstrip tunable wideband frequency and polarisation reconfigurable antenna are investigated. The wideband tunability is achieved by placing the four varactor diodes between circular microstrip patch and circular ring. The impedance bandwidth of 2.09–2.96 GHz (34.52%) is realised by tuning the capacitance value from 4.15 pF (0 V) to 0.94 pF (6 V). Both frequency tunability and polarisation reconfigurability are controlled in the antenna using the proposed cascaded branch line coupler feed network. The four single pole double throw and two dual in‐line package switches are used in the feed network to control the tunable impedance bandwidth of the antenna over a wideband from 1.25 to 2.95 GHz. The vertical linear polarisation and horizontal linear polarisation (H‐LP) are achieved by any one of the feed port excited in the antenna. Similarly, the right‐hand circular polarisation and left‐hand circular polarisation are realised by exciting both the feed ports in the antenna with±90° phase difference. The impedance bandwidth of proposed feed network is well matching with the tunable bandwidth of the patch antenna. Simulated and experimental verification results show good agreement.

본 논문은 UHF RFID 시스템을 위해 편파를 선택할 수 있는 리더 안테나를 설계 및 구현하였다. 제안된 리더 안테나는 두 개의 급전부를 가지는 마이크로 스트립 패치 안테나와 두 개의 SPDT 스위치와 하나의 SP4T 스위치와 3dB hybrid coupler로 구성되어 있다. 각각의 스위치 전압을 조절하여 수직 방향의 선형 편파와 수평 방향의 선형 편파, 좌수 원형 편파와 우수 원형 편파를 선택할 수 있다. 제안된 안테나는 902MHz~928MHz 대역에서 VSWR 2:1 기준으로 UHF RFID 주파수 대역인 902MHz~928MHz를 만족한다. 안테나의 최고이득은 X-Y Plane을 기준으로 선형 편파가 선택되어질 때 7.71dBi, 7.55dBi 로 측정되었고 원형 편파가 선택되어질 때 7.31dBic, 7.81dBic 로 측정되었다. 또한 원형 편파(LHCP, RHCP)가 선택 되어질 때 축비는 각각 2.01~2.83dB, 2.02~2.60dB로 측정되었고 이는 3dB 이하의 축비를 만족한다. TIn this paper, it is designed the polarization selective antenna for UHF RFID system. The proposed antenna is consist of microstrip patch antenna with dual feeding and two SPDT switches and a SP4T switch and 3dB hybrid coupler. Through control of voltage of switches, the proposed reader antenna can select horizontally linear polarization, vertically linear polarization, left-hand circular polarization (LHCP) and right hand circular polarization (RHCP). The proposed reader antenna satisfied 2:1 VSWR at 902MHz~928MHz. and it has under 3dB AR(axial ratio). Peak gain of antenna is 7.71dBi, 7.55dBi with linear polarization and 7.31dBic, 7.81dBic with circular polarization at x-y plane. Also Axial ratio of antenna is 2.01~2.83dB and 2.02~2.60dB respectively. It is satisfied 3dB axial ratio.

A wideband circularly polarized reconfigurable microstrip patch antenna fed by L- shaped probes is proposed. The L-shaped probes are connected to a matching network underneath the ground plane, which two polarizations, right hand circular polarization (RHCP) or left hand circular polarization (LHCP), could be excited. With the use of PIN diodes and some biasing/RF components, an electrical switch has been designed. The antenna is capable to radiate either RHCP or LHCP by a single feeding port, with suitable biasing voltage on the switches. Preliminary study found that the antenna attains a bandwidth of about 20% with VSWR<2 and axial ratio<3 dB.

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.

A new broadside and conical beam reconfigurable dielectric resonator antenna (DRA) with three orthogonal linear polarizations (LPs) and two orthogonal circular polarizations (CPs) agility is presented. It consists of a quad-strip-fed DRA element and a reconfigurable feeding network. First, the DRA element is designed to make unidirectional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm{HEM}}_{11 \delta }$ </tex-math></inline-formula> mode and omnidirectional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm{TM}}_{01 \delta }$ </tex-math></inline-formula> mode operate in the same wide band by tactfully removing a concentric annular column from its interior. Furthermore, a center-loaded metal post helps to improve the impedance matching of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm{TM}}_{01 \delta }$ </tex-math></inline-formula> resonance significantly. Afterward, the switchable feed network is designed to implement diverse phase distributions of four output ports, i.e., providing the quad-port in-phase excitation, dual-port differential excitations, and quad-port sequentially rotated phase excitation strategies for a vertical LP, ±45° slant horizontal LPs, and two CPs, respectively. Finally, a fully functional prototype is designed, fabricated, and measured to validate the design. The measured results show that the overlapping impedance bandwidth of 36.8% for all the states and the axial-ratio bandwidth of 33.8% for the CPs are obtained.

A novel dual-sense polarization reconfigurable dual-band microstrip antenna

In this letter, a hexa-polarization reconfigurable fixed-frequency beam scanning leaky-wave antenna (LWA) operating in the millimeter-wave band is developed. Two parallel gap waveguides (GWs) are used as the basic transmission structure, and wide serrated ridges are adopted to produce quasi-TEM mode and slow-wave transmission in the GWs. A square patch array excited by the GWs is designed to generate radiation with desired polarization. A control structure loaded with PIN diode is applied to tune the working state of each patch unit. Then based on the holographic theory, the hologram on the antenna aperture can be manipulated by controlling the states of all the patch elements. In this way, six polarizations can be obtained (±45° linear polarizations, horizontal polarization, vertical polarization, left-hand circular polarization and right-hand circular polarization), and independent fixed-frequency beam scanning for each polarization can be achieved. In the measurement, a beam-scanning range of 100° is realized for each polarization state, and the property of two circular polarizations is also verified by the measured axial ratios. Therefore, this LWA shows potential in the millimeter-wave applications that demand polarization agility and fixed-frequency beam scanning.

Polarization reconfigurable annular ring slot antenna design

In this paper, a framework of a novel communication system based on circular polarization modulation called Offset Circular Polarization Modulation (OCPM) is proposed which not only increases the channel capacity but also provides data security against eavesdropping. In conventional circular polarization modulation (CPM), only one bit of data (1 or 0) can be transmitted at one time by using either left hand circular polarization (LHCP) or right hand circular polarization (RHCP), limiting it to only 2-states polarization modulation scheme. However, the proposed OCPM scheme provides eight-fold increase in the polarization states. In OCPM, typical CPM constellations (LHCP or RHCP) can be shifted to different quadrants using an offset vector in order to increase the number of polarization states. In addition to switching the swing of circular polarization (CP) in OCPM, quasi-dc offset vectors are added to the horizontal and/or vertical components of the CP wave with different combinations. The reason why quasi-dc offset vectors have been used is because pure dc offsets cannot be wirelessly transmitted. The quadrant of the modulation is determined by the offset vectors. For instance, in order to shift a CP constellation (LHCP or RHCP) in the first quadrant, two positive offset vectors are required: one along horizontal-axis and the other along vertical-axis of the EM wave. Thus, OCPM is a dual dimension CPM scheme with polarization state as well as offset state. The eavesdropper would require both dimensions (i.e. Polarization state and offset state) to correctly determine the overall state of the OCPM scheme.

A novel reconfigurable microstrip antenna that can switch operating polarization states among vertical and horizontal linear polarization, left- and right-hand circular polarization is proposed in this paper. The original square patch is fed by two orthogonal ports, which excite horizontal and vertical linear polarizations. Two opposite corners are slotted on the patch with a diode being loaded on every slot. By controlling PIN diodes and using different feed ports, the polarization sense alternates among four states. The antenna's performances of the four polarization states are simulated and measured. This polarization agile antenna has good radiation characteristics, concise structure and low cost.

A reconfigurable antenna with a compact size and quad-polarization reconfigurability is presented. By employing a switchable feed scheme, the antenna can operate at single-fed and dual-fed modes. At single-fed mode, the feed structure allows output ports switching to produce the excitations for either slant +45° or -45° linear polarization (LP). At dual-fed mode, it serves as a switchable phase-shifting power splitter for generating left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP). To realize a simple and space-saving configuration, the antenna makes efficient use of the proposed feed structure, which is highly shared among the four polarization states. Measured results show that the antenna exhibits operating bandwidths of 230 and 260 MHz at circular polarization CP and LP states, respectively. Moreover, stable broadside radiation patterns as well as moderate gains could also be obtained.

Concentric circular compound reconfigurable microstrip patch antenna for wireless applications