New Proximity Coupled Feeding Method for Reconfigurable Circularly Polarized Microstrip Ring Antennas

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.

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 spiral antenna is a broadband element exhibiting circular polarization: right-hand circularly polarized (RHCP) or left hand circularly polarized (LHCP) depending on its winding. An array of spirals with dual polarization must therefore have spirals winding both right and left. A simple configuration alternates every other RHCP element with a LHCP element. In that case, the spacing is such that the frequency at which the grating lobes appear (so the maximum frequency of the array) is lower than the minimum frequency of the spiral (and, so, of the array, with a return loss less than −10dB).

A wideband dual-sense circularly polarization helical antenna with axial dual-beam operation mode is proposed in this paper. The proposed antenna is composed of two-arm helical wires with opposite sense of rotation, which produces left-hand circularly polarization (LHCP) wave and right-hand circularly polarization (RHCP) wave from each helical arm respectively. By adjusting the geometry parameters of the helical wire, the axial dual-beam radiation is realized. The antenna, fed at the center of these two helical wires with seven turns, is simulated, and good performance is achieved. In the frequency range from 1.7 GHz to 3.05 GHz, the gain of LHCP and RHCP is about 8 dBi, along with axial ratio below 3 dB in beam-width from 30 to 120 degrees. The cross polarization is lower than −20 dB in both two boresight directions at 2.8 GHz.

A design of dual circularly polarized antenna is proposed. By two dual L-shaped probe structure, dual-sense circular polarization (CP) for radio astronomy is achieved. The dual L-shaped probes are place in the radial direction of a circular ring to obtain both right hand circular polarization (RHCP) and left hand circular polarization (LHCP). According to our simulation results, the proposed antenna element could achieve −10dB-level of |S 11 | and more than −20dB-level of isolation in frequency range of 1.4 – 1.7 GHz. The antenna element broadside gain is approximately 8.5 dBic. The axial ratio (AR) below 3dB is more than 300 MHz in each circular polarization state. The details of simulation results for the proposed design are presented and discussed.

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.

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.

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.

A circular polarization (CP) antenna that can switch between right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP) modes has been designed and introduced for 5G applications in the 3.5 GHz frequency band in this work. The proposed antenna comprises a crossed dipole fed by a 90° hybrid coupler. The axial ratio (AR) enhancement of 190 MHz is achieved by vertically stacking a substrate with a distance of λ / 4 from the ground plane, including an annular ring-shaped parasitic element above a circular-shaped disc. Consequently, by creating surface current rotation on the parasitic elements, the CP performance of the antenna is improved. According to the experiments, a wide impedance bandwidth of 930 MHz (3.19-4.12 GHz) and an overlapped AR bandwidth of 23.5% for both modes are achieved. The overall size of the antenna is 100 × 92.5 × 24 m m 3 , and the gain is stable across the operating frequency band with a peak value of 6.78 dBic.

In this manuscript, a compact circularly polarized MIMO antenna with 100% 3-dB axial ratio attributes has been conceived for 5G NR Sub-6 GHz frequency bands. The simulated and measured findings indicate that the suggested antenna has an impedance bandwidth (−10 dB) in the range of 2.88–3.88 GHz; nonetheless, the measurements show a range of 3.0–4.4 GHz, with a 3-dB Axial ratio Bandwidth (ARBW) in the area of 2.73–5.42 GHz (Simulated) and 2.75–5.45 GHz (Measured), respectively. With left-handed circular polarization (Port-1 and Port-2) and right-handed circular polarization (Port-3 and Port-4), the antenna spans the proposed 5G band spanning N77 (3.3 to 4.2 GHz) and N78 (3.3 to 3.8 GHz). The suggested MIMO antenna design consists of a singular structure including an L-shaped radiating element and a rectangular ring-shaped ground plane, both co-planar. A compact MIMO module with two ports is constructed by reflecting the L-Shape radiator across the x-axis, while a MIMO module with four ports can be generated by reflecting the two-port antenna image across the y-axis. The functionality of the proposed module as an antenna have been validated by simulation, including the calculation and analysis of various antenna and diversity characteristics. The modelling results are then corroborated by the measurement outcomes of the constructed antenna. The suggested design is deemed suitable for use as a MIMO antenna due to its optimum value of envelope correlation coefficient (ECC), diversity gain (DG), channel capacity Loss (CCL), total active reflection coefficient (TARC), mean effective gain (MEG) and its isolation between the antenna components, which exceeds 18 dB. The suggested design demonstrates a high degree of concordance between the simulated and measured outcomes.

Polarization reconfigurable annular ring slot antenna design

ABSTRACTIn this work, several techniques are presented to switch operated bandwidth and circularly polarized pattern of the coplanar waveguide (CPW)-fed monopole antenna. A fork-like conducted strip monopole is utilized for the radiating element. Two p-i-n (PIN) diodes are embedded in the antenna structure to realize the switchable capability of frequency band and circular polarization. By electronically turning on or off these diodes, a right-hand circularly polarized (RHCP) wave at 1.57 GHz for the global positioning system (GPS) is not only generated, but a left-hand circularly polarized (LHCP) wave at 2.33 GHz for satellite digital audio radio (SDAR) service system is also achieved. Measured results show that the 3-dB axial ratio (AR) bandwidths are 110 MHz (1.49–1.60 GHz, 7.1%) around 1.57 GHz and 70 MHz (2.29–2.36 GHz, 3.0%) around 2.33 GHz, whereas the impedance bandwidths are 430 MHz (1.38–1.81 GHz) and 670 MHz (2.05–2.72 GHz).

The frequency‐dependent circular dichroism is proposed to extend the wave manipulating capability of coding metasurfaces. As a proof of concept, the bispectral circular dichroic coding metasurfaces (CDCMs) are realized using circular dichroism resonators (CDRs) implemented via introducing loss resistors into the circular polarization conversion resonators. The CDRs are distinguished into left‐handed CDRs and right‐handed CDRs. Left‐handed CDRs absorb left‐handed circularly polarized (LCP) wave and convert right‐handed circularly polarized (RCP) wave into LCP wave. Conversely, they are defined as right‐handed CDRs. Two bispectral CDRs are designed with the left‐handed (right‐handed) and right‐handed (left‐handed) working bands in 7–8.5 and 22.2–22.5 GHz, respectively. And then, 1 bit bispectral CDCM with 0101…/1010… coding sequence is designed. Simulated results indicate that the designed CDCM strongly absorb the incident LCP (RCP) waves in the frequency region 7–8.5 GHz (22.2–22.5 GHz), but the incident RCP (LCP) waves are anomalously reflected into four beams of the LCP (RCP) waves with high efficiency. The measured results agree well with the simulations. The results in this work may provide an effective solution for the inverse and helicity‐dependent manipulation of the electromagnetic waves in two distinct frequency regions.

In In this paper, two low profile, single fed cavity backed slot antennas providing a circularly polarized (CP) wave are introduced. One of the antennas presents a right-handed CP (RHCP) wave, while the other one offers a left handed CP (LHCP) wave. The proposed antennas consist of a square shaped Substrtae Integrated Waveguide (SIW) cavity incorporatng two couples of radiating slots to radiate two field components with 90° phase difference far from the antennas. A single layer of printed circuit board (PCB) process is employed for both antennas to provide low cost, light weight and also to be compatible with planar circuits. An inset feed line is used to excite two orthogonal modes including TE120 and TE210 with suitable phase difference for generating CP wave. Antenna structures is numerically evaluated using High Frquency Structure Simulator (HFSS) and a prototype of RHCP antenna is fabricated and its radiation charateristics including reflection coefficient, gain, Axial Ratio (AR) and radiation patterns are reported.