Circular Waveguide Polarizers Research Articles

Dual-Circularly Polarized Array Antenna Based on Gap Waveguide Utilizing Double-Grooved Circular Waveguide Polarizer

This article presents a dual-circularly polarized array antenna based on gap waveguide technology operating at E-band. Double-grooved circular waveguide polarizers that utilize two annulus grooves placed at 45° and 135° offset from both excitation ports are used in this work. The operating principles of the polarizer are analyzed. Multilayer design using gap waveguide is implemented on the basis of the polarizer. The antenna consists of six layers, including three layers for the feeding networks, one layer for the polarizer, one layer of back cavity, and another layer of radiating grid. A 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 unit cell is proposed first and employed to realize an 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 planar array. Corporate feeding networks that use compact E-plane T-junctions and H-plane T-junctions are proposed. The antenna has been fabricated and verified by measurements. The measured results of S-parameters agree well with the simulation and show that reflection coefficients are better than −10 dB for both circular polarizations (CPs) from 76 to 81 GHz. The measured isolation between the input ports is larger than 25 dB in the operating band. The far-field measurements show that the antenna has realized gain larger than 24 dBi and axial ratios less than 1.5 dB from 76 to 81 GHz at boresight direction.

Circular Waveguide Polarizer for Weather Radars and Satellite Information Systems

This research presents the design and main electromagnetic characteristics of the novel compact microwave waveguide polarizer. The developed device's structure is based on a circular waveguide and anti-phase conducting posts located in it. The application of a circular waveguide instead of a square one allowed simple integration of a polarizer with corrugated horn antennas. The obtaining of required phase difference using a posts-based design provides the possibility of fine tuning of the developed circular waveguide polarizer after its manufacturing process. In addition, simultaneous adaptive operation at orthogonal circular and linear polarizations is available in the antenna system including a polarizer with posts. An automatic control of posts height must be applied in a waveguide in order to provide this option. Numerical simulation, optimization, manufacture and measurements of the polarizer's characteristics were carried out in the operating band 7.4-8.5 GHz. Measured characteristics proved that the suggested circular waveguide polarizer provides good matching and polarization performance. Developed circular waveguide polarizer can be integrated in corrugated horn antenna systems and applied in modern weather radars and satellite information systems.

Broadband Septum Polarizer With Triangular Common Port

This article presents a novel broadband septum polarizer with a relative bandwidth (BW) of 37.8%. This is significantly more than the approximate 25% BW of square and circular waveguide polarizers. It is enabled by using an equilateral triangular common port waveguide, which guarantees the largest possible frequency range between fundamental and next higher order mode cutoff. The transition between the triangular section and the rectangular input waveguides, which includes the septum, is designed to accommodate this large BW. The simulation is validated using a polarizer designed for 75–110 GHz and fabricated by conventional precision milling. A second polarizer is realized for the 18-to-26 GHz range by employing additive manufacturing to demonstrate the advantages of this technology in this context. In both cases, the axial ratio remains below 1.3 dB, whereas the input port isolation and the input return loss exceed 17 and 15 dB, respectively.

A Ka-Band Circularly Polarized Substrate Integrated Cavity-Backed Antenna Array

A high-gain 4 × 4 substrate integrated waveguide (SIW) circularly polarized (CP) antenna array at a Ka-band with a quadruple-ridge waveguide polarizer is proposed in this letter. The antenna array consists of 16 cavity-backed slot antenna elements, quadruple ridge waveguide polarizers, and SIW T-type power dividers. Dominant resonant mode TE110 is excited in the cavity-backed slot antenna element. The measured impedance bandwidth ( S 11 < –10 dB) is from 35.3 to 35.55 GHz, and 3 dB axial-ratio bandwidth is from 35.24 to 35.57 GHz. In addition, the maximum measured gain of 18.14 dBi at the boresight is experimentally obtained at 35.42 GHz. The antenna prototype was fabricated by a multilayer printed circuit board technology. To the best of our knowledge, the quadruple-ridge waveguide is used as polarizer to produce CP signals for the first time. Compared with an aperture antenna with a conventional rectangle or a circular waveguide polarizer, this work has high aperture radiation efficiency as well as compact size. This design idea may open a new way for development of millimeter-wave high-efficiency arrays.

A New Design of Ka-Band Circularly-Polarized Antenna

A new ka-band circularly-polarized antenna is presented in this paper, in which a linearly-polarized wave is conversed into a circularly-polarized wave with a circular waveguide polarizer. After simulation and optimization with HFSS (High Frequency Structure Simulator), a compact circularly-polarized antenna is designed with a total height less than 25mm. More simple and easier structure is adopted to achieve a low-profile circularly-polarized antenna.

Circular TE11-based waveguide polarizer for efficient coupling to electron Bernstein wave

A circular waveguide polarizer for 2.45 GHz microwaves has been designed and produced for electron Bernstein (EB) wave heating and current drive experiments on the low aspect ratio Torus experiment (LATE) device. In the experiments the microwaves are injected obliquely to the toroidal field to drive current carrying fast electrons. In the LATE case of the oblique injection of long free space wavelength waves onto a small plasma the coupling to the EB waves from the injected electromagnetic waves is improved when the injected waves have appropriate elliptical polarizations depending on the injection angle and the density gradient at the upper hybrid resonance layer (Igami et al 2006 Plasma Phys. Control. Fusion 48 573). Any elliptically polarized mode can be generated from a circular TE11 mode by the combination of a half wave section and a quarter wave section of circular waveguide. The transformation of polarization arises from the difference in axial wave numbers between an orthogonal pair of modified circular TE11 modes, which is realized by the insertion of a Teflon plate in a circular waveguide made of aluminum. Such a polarized wave is launched from the open end of a circular waveguide toward the plasma. An elliptically polarized mode adjusted to a steep density gradient and injected obliquely to the toroidal field has been found to be effective to sustain a highly over-dense plasma.

A Novel Broadband Q-Band Polarizer with Very Flat Phase Response

We present a 33–50 GHz circular waveguide polarizer based on a broadband combination of retarders. The device was designed within the FP7 RadioNet APRICOT (‘All Purpose Radio Imaging Cameras on Telescopes’) consortium for the development of focal plane arrays for radiotelescopes. The device is based on a Pancharatnam recipe used in optics and behaves as a polarization transformer, from circular to linear and vice versa. This novel design of polarizer exhibits an unprecedented performance combining extremely flat differential phaseshift across the whole band, very low losses and very low Amplitude Unbalance (AU). It can be used in astronomical instruments or telecommunication antennas where very high purity circular polarization is required. The design was manufactured and then tested using a Vector Network Analyzer (VNA). Averaged across a 40% bandwidth the measured RL, IL, amplitude unbalance and differential phase-shift were respectively:−31.4/−35.3 dB, −0.09/−0.06 dB, 0.04 dB and 90.0 ± 0.4°.

Full-wave design and optimization of circular waveguide polarizers with elliptical irises

We describe the design and optimization of a new polarizer structure realized in circular waveguide with insertion of elliptical irises. The device is compact, showing a considerable reduction in size and weight when compared to previously known realizations. It requires manufacturing by milling techniques only and, since it is composed entirely by waveguides with separable cross sections, it is also well suited for electromagnetic modeling. Measured and theoretical results for a polarizer with a 90/spl deg//spl plusmn/1/spl deg/ differential phase shift and a return loss better than 35 dB for both polarizations over the operating frequency band confirm the validity of the proposed design.

A design of novel grooved circular waveguide polarizers

This paper presents novel types of polarizers that are composed of grooved circular waveguides. The presented polarizers are suitable for realizing high-performance and low-fabrication cost in the Ka-band and above because of simple structure. Accurate analysis and design of the polarizers are performed using full-wave mode-matching techniques applied to the circular-to-rectangular waveguide T-junctions and cross-junctions. Ka-band grooved circular waveguide polarizers fabricated with the aid of the analysis and design techniques have realized excellent performance without tuning elements.

Full-wave design of dual-band double-septum circular waveguide polarizers

A dual-band circular waveguide polarizer for TTC (telemetry, tracking, and command) applications is presented. The structure is composed of two corrugated metal sheets inside a circular waveguide allowing easy manufacturing and low cost. A rigorous CAD which combines the mode-matching and the finite-element techniques (MM–FEM) permits us to obtain the generalized scattering matrix (GSM) and to take into account the higher order mode interaction between the step discontinuities. The experimental polarizer results show excellent agreement with theory. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 99–103, 1999.