A ring antenna for dual-sense circular polarization

A new reconfigurable single-feed circular microstrip antenna with polarization diversity is proposed. The simple structure of this antenna contains a radiating circular patch, four switches (PIN diode), and a 50 Ω microstrip feed line. It can be switched between four different states: two states for linear polarization (LP), one state for left hand circular polarization (LHCP) and one for right hand circular polarization (RHCP). Simulation and experimental results show that the proposed antenna demonstrates a good impedance bandwidth, and axial ratio in the circularly polarized states.

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.

In this letter, a compact, planar circularly polarized (CP) sub-GHz slot-based multiple-input-multiple-output (MIMO) antenna with dual sense CP along with polarization bandwidth reconfigurability is presented. The pentagonal reactively loaded slot is fed by two folded tapered feedlines to achieve CP. The antenna offers left-hand-circular polarization (RHCP) with the as well as right hand circular polarization (LHCP). The antenna exhibit linearly polarization (LP) by exciting two ports simultaneously. Moreover, the antenna CP resonance can be reconfigured by varying the capacitance of the varactor diode. The antenna has a wide −10 dB operating frequency band from 578–929 MHz. while the axial ratio (AR) bandwidth ranges from 490–810 MHz. Moreover, the two elements MIMO are optimized and placed on compact dimensions 100 × 100 × 0.76 mm3 to realize pattern diversity. The antenna’s key characteristics are compact size, wide-band sub-GHz operation, dual sense CP, polarization bandwidth reconfigurability and good MIMO performance. Thus, it is a suitable candidate to be utilized in CubeSats applications in sub-GHz bands.

A single-feed circular microstrip antenna with reconfigurable polarization capability is proposed. This antenna has a simple structure, which consists of a radiating circular patch, five switches (PIN diode), three matching stubs, and a 50 microstrip feed line. It can be switched between 4 different states: two states (low-frequency and high-frequency) for linear polarization (LP), one state for left hand circular polarization (LHCP) and one for right hand circular polarization (RHCP) by controlling the bias voltage of two PIN diodes. At the same time, three switchable matching stubs are used for matching every polarization state. Simulation results and experimental results show that the proposed antenna demonstrates a low cross polarization level, good impedance bandwidth, and a very good axial ratio in the circularly polarized states.

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.

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 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.

This article presents a circular polarized enclosed dielectric resonator antenna (DRA), operating at 5.8 GHz. The design consists of a twist DRA, which is enclosed in a box to give stability to the structure. The circular polarization of the antenna depends on the sense of twisting the top with respect to its base to achieve Left Hand Circular Polarization (LHCP) or Right Hand Circular Polarization (RHCP). The antenna was manufactured using 3D printing and low-loss dielectric filament. The measurement results show the two resonance frequencies and an axial ratio below 3 dB at the operational frequency, while exhibiting a bandwidth and gain compatible for unmanned aerial vehicle (UAV) applications.

This letter presents a dual-sense circularly polarized (CP) microstrip patch antenna with a dual-coupled line. The rectangular patch antenna operating in TM01 mode is utilized as a basic design, and a single-coupled line is introduced to excite the TM10 mode with a phase difference of 90°, generating CP operation. As different polarizations can be obtained by changing the position of the single-coupled line, a dual-coupled line is introduced to the rectangular patch antenna to excite two CP modes with different polarizations. The prototype of the dual-band dual-sense CP antenna is fabricated and measured. The measured results illustrate that the dual-sense CP antenna obtains a wide impedance bandwidth of 7.95% and dual axial ratio (AR) bandwidth of 0.33% for the left-hand circular polarization (LHCP) and 0.72% for the right-hand circular polarization (RHCP). Furthermore, the antenna has a wide 3 dB axial-ratio beamwidth and a small frequency ratio of 1.04.

In this paper, a circular polarized corrugated horn fed nonuniform reflectarray antenna of dual sense i.e left hand circular polarization (LHCP) and right hand circular polarization (RHCP) is presented for X band applications. The antenna consists of only a grounded dielectric layer 2.4 permittivity with variable thickness h from 0.5 to 10 mm. Design is completed within the 3D CST environment. The feeding unit having the circularly polarized characteristic is achieved by exciting two modes in a circular waveguide simultaneously and feeding the X-band Corrugated Horn Antenna (CHA). It can be concluded that all the simulated 3D CST radiation characteristics have shown that based on the feed port excitated the antenna can radiate LHCP or RHCP fields in a good performance.

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.

In this paper, two low profile, single fed cavity backed slot antennas for producing circular polarization (CP) wave are introduced. One of the structures presents right handed CP (RHCP), while the other one offers left handed CP (LHCP). A single layer of low cost printed circuit board (PCB) is employed for both antennas providing low cost, light weight and also easy integration with planar circuits. An inset microstrip line is used to excite two orthogonal modes, TE120 and TE210, with 90° degree phase difference for generating CP wave. Antenna structure is numerically evaluated using High Frequency Structure Simulator (HFSS) and results including reflection coefficient, gain, and axial ratio (AR), and radiation patterns are reported.

We present the integration of Germanium Telluride (GeTe), a phase change material (PCM), within a conventional patch antenna operating in the millimeter wave domain (~ 30 GHz). The GeTe is integrated within the four corners of a metallic patch antenna, which is excited by a microstrip line. The phase changes between the insulating (OFF) and metallic (ON) states of GeTe will be controlled using shorts ultraviolet (UV) laser pulses. That allows the reconfigurability of the device between a linear polarization (LP), a left hand circular polarization (LHCP) and a right hand circular polarization (RHCP). Simulated results of antenna show total efficiencies up to 75 % for the circular polarization (CP) and a 3 dB bandwidth of axial ratio (AR) over 350 MHz around 29.5 GHz.

This article presents the circularly polarized antenna operating over 28 GHz mm-wave applications. The suggested antenna has compact size, simple geometry, wideband, high gain, and offers circular polarization. Afterward, two-port MIMO antenna are designed to get Left Hand Circular Polarization (LHCP) and Right-Hand Circular Polarization (RHCP). Four different cases are adopted to construct two-port MIMO antenna of suggested antenna. In case 1, both of the elements are placed parallel to each other; in the second case, the element is parallel but the radiating patch of second antenna element are rotated by 180°. In the third case, the second antenna element is placed orthogonally to the first antenna element. In the final case, the antenna is parallel but placed in the opposite end of substrate material. The S-parameters, axial ratio bandwidth (ARBW) gain, and radiation efficiency are studied and compared in all these cases. The two MIMO systems of all cases are designed by using Roger RT/Duroid 6002 with thickness of 0.79 mm. The overall size of two-port MIMO antennas is 20.5 mm × 12 mm × 0.79 mm. The MIMO configuration of the suggested CP antenna offers wideband, low mutual coupling, wide ARBW, high gain, and high radiation efficiency. The hardware prototype of all cases is fabricated to verify the predicated results. Moreover, the comparison of suggested two-port MIMO antenna is also performed with already published work, which show the quality of suggested work in terms of various performance parameters over them.

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.