Circular Waveguide Polarizers: Types, Selection & Manufacturers

Introduction

Circular waveguide polarizers are essential components in RF and microwave systems. They are used for the conversion between linear and circular polarizations to ensure optimal signal transmission and reception. Their applications span across different domain areas which include satellite communications, weather radar systems and other high frequency technologies.

Circular waveguide polarizer selection guide

Selecting the appropriate polarizer involves considering factors such as frequency range, bandwidth, insertion loss and physical dimensions. Following are typical specifications or parameters to be considered for the selection of appropriate polarizer as per application usage.

• Operating frequency range : The range of polarizer should be as per your system frequency requirement.
• Bandwudth : Wider bandwidth allows polarizer to operate effectively over broad range of frequencies.
• Axial Ratio : It indiates purity of circular polarization. Lower the value better is the performance.
• Insertion loss : It represents signal loss introduced by the polarizer in the RF signal path.
• VSWR or Return Loss : VSWR or return loss indicates impedance matching. VSWR of 1:1 is ideal. Higher the return loss better is the impedance matching.
• Polarization Type : LHCP, RHCP, Dual
• Waveguide size and interface : Ensure compatibility with existing systems where it has to be mounted.
• Mechanical specifications : Consider factors like flange type, material and finish.
• Environmental conditions : Assess operating temperature ranges and other environmental factors as per application usage.

Circular Waveguide Polarizer

By carefully evaluating these specifications in relation to your system requirements, you can select a circular waveguide polarizer that ensures optimal performance and reliability.

Example : Model : SAS-233-39642-F1 from Eravant California, USA Features : It is linear to circular polarizer which operates at 22.5 GHz (K band) with +/- 2.5 GHz bandwidth. It offers insertion loss of about 1.0 dB, an axial ratio of about 1.1, and return loss of about 20 dB.

Circular polarizer Types

Following are common typs of circular polarizers based on their functions and unique structures.

1. Septum Polarizer : It converts linear polarization to circular polarization by introducing 90 degree phase shift between orthogonal modes. It utilizes stepped septum within square or circular waveguide to achieve required phase shift as desired.
2. Grooved circular waveguide polarizer : It facilitates polarization conversion by inducing anisotropy through periodic grooves. In its structure, it incorporates grooves or corrugations inside waveguide walls after modifying propagation characteristics to achieve polarization transformation.
3. Elliptical waveguide polarizer : It converts linear to circular polarization by exploiting anisotropic properties of elliptical waveguides. This waveguide polarizer type employs waveguide sections with elliptical cross sections. They are carefully designed to induce necessary phase shift between orthogonal modes.
4. Dielectric Insert Polarizer : This polarizer type achieves polarization conversion by introducing phase delay between orthogonal components using dielectric materials in the form of slabs or plates. They are appropriately placed to create desired phase difference to achieve polarization transformation.
5. Corrugated waveguide polarizer : It supports circular polarization over broad bandwidth by modifying mode propagation through corrugations. There are periodic ridges or teeth along the waveguide walls which alter impedance of waveguide and its mode structure to facilitate polarization conversion.

Leading waveguide polarizer manufacturers

Summary

In summary, circular waveguide polarizers play a pivotal role in modern RF and microwave communication systems by facilitating efficient polarization control. With a range of manufacturers providing diverse polarizer designs, engineers and system integrators have access to solutions that meet the stringent demands of communication infrastructures.