Right-hand Circular Polarization Mode Research Articles

Gravitational wave constraints on spatial covariant gravities

The direct discovery of gravitational waves (GWs) from the coalescence of compact binary components by the LIGO/Virgo/KAGRA Collaboration provides an unprecedented opportunity for exploring the underlying theory of gravity that drives the coalescence process in the strong and highly dynamical field regime of gravity. In this paper, we consider the observational effects of spatial covariant gravities on the propagation of GWs in the cosmological background and obtain the observational constraints on coupling coefficients in the action of spatial covariant gravities from GW observations. We first decompose the GWs into the left- and right-hand circular polarization modes and derive the effects of the spatial covariant gravities on the propagation equation of GWs. We find that these effects can be divided into three classes: 1) frequency-independent effects on GW speed and friction, 2) parity-violating amplitude and velocity birefringences, and 3) a Lorentz-violating damping rate and dispersion of GWs. With these effects, we calculate the corresponding modified waveform of GWs generated by the coalescence of compact binaries. By comparing these new effects with the publicly available posterior samples or results from various tests of gravities with LIGO/Virgo/KAGRA data in the literature, we derive the observational constraints on coupling coefficients of the spatial covariant gravities. These results represent the most comprehensive constraints on the spatial covariant gravities in the literature.

Tri-polarization Reconfigurable Fabry-Perot Resonator Antenna in Ku-band

In this paper, a broadband tri-polarization reconfigurable antenna applied to polarization diversity is proposed. A partially reflective surface (PRS) is designed to form an air-filled resonator cavity. The reflection phase of the PRS has a positive phase gradient in order to achieve the characteristics of the proposed antenna gain enhancement in the wideband. A metal patch of a four-arm meander structure is used as the radiation structure and the feeding is realized through a four-channel rotating feeding network with equal amplitude and 90∘ phase difference. The feeding network is connected to the radiation structure through four metallized vias. In order to realize the polarization reconfigurability, the PIN diodes and the corresponding DC bias circuit are integrated in the rotating feeding network. The characteristics of horizontal polarization (HP), vertical polarization (VP) and right-hand circular polarization (RHCP) are realized by changing the ON/OFF states of PIN diodes integrated in the feeding network. In order to verify the performance of the proposed antenna, fabrication and testing were carried out. The measurement results show that the -10 dB impedance bandwidths of HP, VP, RHCP are 11% (12.5-14 GHz), 6.4% (13.7-14.6 GHz) and 20% (12.2-14.9 GHz), and the peak realized gains are 9.1, 9.2 and 11.5 dBi, respectively. For RHCP mode, the 3-dB axial ratio bandwidth reaches about 17% (12.35-13.4 GHz and 13.6-14.9 GHz).

Model-independent test of the parity symmetry of gravity with gravitational waves

Gravitational wave (GW) data can be used to test the parity symmetry of gravity by investigating the difference between left-hand and right-hand circular polarization modes. In this article, we develop a method to decompose the circular polarizations of GWs produced during the inspiralling stage of compact binaries, with the help of stationary phase approximation. The foremost advantage is that this method is simple, clean, independent of GW waveform, and is applicable to the existing detector network. Applying it to the mock data, we test the parity symmetry of gravity by constraining the velocity birefringence of GWs. If a nearly edge-on binary neutron-stars with observed electromagnetic counterparts at 40 Mpc is detected by the second-generation detector network, one could derive the model-independent test on the parity symmetry in gravity: the lower limit of the energy scale of parity violation can be constrained within mathcal {O}(10^4mathrm{eV}).

A wideband polarization reconfigurable antenna based on optical switches and C‐shaped radiator

AbstractA wideband polarization reconfigurable antenna based on optical switches and a C‐shaped radiator is proposed. The antenna can achieve three polarization modes, linear polarization (LP), left‐hand circular polarization (LHCP), and right‐hand circular polarization (RHCP). The proposed antenna consists of a simple C‐shaped patch, a modified ground plane, a feeding unit, and two parasitic stubs. Four slots are embedded in the C‐shaped patch properly to adjust the axial ratio (AR) performance for CP modes. And two silicon optical switches are inserted into each brand of the feeding unit. The measured results show that the proposed antenna has a 10‐dB impedance bandwidth of 86.8% (1.82‐4.61GHz) in LP mode, 81.8% (1.3‐3.1 GHz) and 14.1% (3.3‐3.81 GHz) for LHCP mode, and 81.8% (1.3‐3.1 GHz) and 19.2% (3.3‐4 GHz) for RHCP mode. The 3‐dB AR bandwidth is about 49.1% (2.38‐3.93 GHz) for LHCP and 51.4% (2.33‐3.94 GHz) for RHCP. The simulated and measured results show a pretty good agreement. Furthermore, in the range of operating bandwidth from 2.38 to 3.81 GHz, the proposed antenna can satisfy the 2.45 GHz WiFi, LTE 4G, and sub‐6 GHz 5G applications.

A polarization‐reconfigurable array design based on mode combination technique

This article reports a novel polarization-reconfigurable antenna array using the technique of mode combination (MC). It can electronically alter its polarization states between left-hand circular polarization mode, right-hand circular polarization mode, and linear polarization (LP) mode. The antenna array consists of 2 × 2 microstrip antenna elements with one L-slot on each square patch and two PIN diodes located in the slot region. Instead of degenerating circular polarization (CP) and LP modes by exciting different radiation parts of the antenna element, the LP one is combined by orthogonal CP modes generated by adjacent elements of the proposed antenna array. To verify the concept, a prototype is manufactured and tested. Experimental results show that the proposed antenna has an overlapped −10 dB impedance bandwidth of around 11.2% for both CP modes and the LP one. The realized maximum gains are around 7.5 dB for the CP modes and 5.6 dB for the LP mode, which are satisfactory for wireless local area network in wireless communication systems.

Wideband Polarization Reconfigurable Differential Circularly Polarized Antenna

This paper presents a polarization reconfigurable differential circularly polarized (PRDCP) antenna with wide impedance and axial ratio (AR) bandwidth for right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP). The antenna is composed of a bandwidth-improved radiator and a reconfigurable differential-to-single-ended sequential feeding network. The radiator consists of three patches, and four feeding lines to achieve the wide AR bandwidth and stable radiation patterns. The feeding network consists of two stepped coupled line couplers (SCLCs), and two switches that provide switchable quadrature excitations. By digitally controlling the inputs of the switches, the LHCP or RHCP mode can be selected. To verify the feasibility of the PRDCP antenna, a prototype is designed, fabricated, and measured. The measured results show that the bandwidths in the LHCP (RHCP) are 75.6% (81.8%) of a 10-dB matching, 66.7% (71.2%) of a 3-dB AR with stable radiation patterns of 7.4 dBi (7.4 dBi) peak gain.

Microfluidically Polarization-Switchable Metasurfaced Antenna

This letter reports a polarization-switchable metasurfaced antenna, which comprises a source antenna and a metasurface as a superstrate. The metasurface consists of a 4 × 4 microfluidic element array, and each element is designed with a rectangular loop with diagonals formed by microfluidic injection. The left-hand circular polarization (LHCP), right-hand circular polarization (RHCP), and linear polarization (LP) are achieved by microfluidic injection through different channel inlets on the metasurface. The performance of the proposed antenna in terms of polarization reconfigurability, axial ratio bandwidth (ARBW), impedance bandwidth, broadside gain, and radiation pattern is experimentally verified after fabrication. The experimental results show that the proposed antenna achieves a 3 dB ARBW from 2.47 to 2.55 GHz (i.e., fractional bandwidth of 3.18%) for LHCP and RHCP, with the realized peak gains of 5.86 and 5.84 dBi in boresight for LHCP and RHCP, respectively, at 2.51 GHz. The 10 dB impedance bandwidth of the antenna in LP mode is from 2.32 to 2.52 GHz and from 2.41 to 2.59 GHz in LHCP and RHCP modes, respectively (i.e., fractional bandwidth of 7.2%).

Research and design of multimode GNSS antenna technology

With the merits of wide coverage, huge capacity of communications, good transmission quality, etc., Global Satellite Navigation System (GNSS) plays a vital role in the fields, such as the aviation, marine, mapping, timing and information services. As the essential part of satellite navigation system, Antenna’s overall performance is good or bad which have a significant impact on Navigation and Positioning System. In this paper, a multi-mode circular polarization GNSS antenna with single-feed stacked patch combined stub technology is presented. By inserting different cross shape stubs, the top square patch performs GNSS high frequency multi-band circular polarization, and the right-hand circular polarization mode in the GNSS low frequency is achieved through inserting different cross shape stubs in the center of the lower square patch. Theoretical analysis and simulation results show that the proposed multi-mode circular polarization antenna can meet multi-system positioning needs of the terminal users of satellite navigation.