Terminology » Understanding waveguide phase shifting structures : septum, OMT, dielectric vane and corrugated waveguide

Understanding waveguide phase shifting structures : septum, OMT, dielectric vane and corrugated waveguide

septum polarizer omt polarizer dielectric vane corrugated waveguide waveguide phase shifting structures waveguide

Introduction

In high frequency RF and microwave systems, precise control over the phase of electromagnetic waves is essential for optimizing signal performance, beam steering, polarization and power handling. This is where waveguide phase shifting structures such as septum polarizers, orthomode transducers (OMTs), dielectric vane polarizers, and corrugated waveguides play a critical role. These components are widely used across satellite communications, radar systems and advanced test setups.

Waveguide phase shifting structures

Waveguide phase shifting structures are essential in microwave and millimeter wave (mmwave) systems for controlling the polarization and phase of electromagnetic waves. The following are key types of such structures.

1. Septum Polarizer

This polarizer has two input ports and single output port. Input ports have rectangular waveguide connectivity and output port has square waveguide connectivity. When signal is applied to one of the input port, it generates RHCP signal at output port. When the signal is applied to the other input, output is an LHCP signal. The main application of septum polarizer is to support two channels over single wireless communication link using shared common band.

2. OMT Polarizer

OMT (Orthomode Transducer) separates or combines two orthogonally polarized signals within waveguide. An OMT structure consists of two rectangular waveguide ports. These ports are coupled to square or circular common port. OMT enables simultaneous transmission and reception of the signals with orthogonal polarizations. OMT provides isolation between paths and also protects sensitive receiver from high power transmit signal. OMT polarizer devices are commonly used in radar, communication link, dual polarized VSATs etc.

Circular Waveguide Polarizer septum, OMT, dielectric vane & corrugated waveguide

3. Dielectric Vane polarizer

This polarizing device consists of thin dielectric slabs inserted into waveguide at 45 degree angle to the electric field. These vanes introduce phase delay in one component of the electric field which converts linear polarization to circular polarization or vice versa.

  • Benefit : Can operate over full waveguide band
  • Limitation : Can handle limited power due to thin dielectric material

4. Corrugated waveguide phase shifter

This structure contains periodic ridges or grooves on its inner surface. It introduces differential phase shifts between orthonal modes. With the proper design of corrugations, 90 degree phase shift can be achieved which helps in conversion of linear to circular polarization.

  • Benefit : Suitable for high power applications, can be optimized as per specific band requirements.

5. Adjustable polarizer

This device allows user to rotate polarizing structure. Hence polarization can be varied among LHCP, RHCP and linear types. The adjustable polarizers are found in antenna test ranges. These devices are used to match polarization of transmitted signal as per receiving antenna polarization.

ManufacturersProduct offerings
Custom Microwave Inc.The company offers waveguide phase shifters in high frequency range. Model numbers include VP12R, VP19R, VP28S and so on.
Fairview MicrowaveThe company offers these waveguide devices for various applications , model : SMW42PS1001 supports 18 to 26.5 GHz, 1.5 W , WR42, 0 to 180 degree phase shift, 1dB insertion loss etc.
Narda-MITEQModel no. 137-P150-360 supports WR137 WG, 360 degree phase shift, 5.85 to 8.2 GHz, 100 W CW Power, 0.9 dB insertion loss.
EravantThe company offers high frequency waveguide components including phase shifting structures. Model : STP-18-12-M2 supports 60 to 90 GHz, 0.6 to 0.8 W power, 0 to 180 degree shift, WR12 waveguide dimension and 0.5 dB insertion loss.
RF-LambdaThe company provides variety of waveguide phase shifters. Model number : RWPSHT19D180 supports WR19 dimension, 180 degree phase shift, 40 to 60 GHz, 10 to 20 Watt power and 0.3 dB insertion loss.
Pasternack Enterprises Inc.The company offers phase shifters for various waveguide dimensions and frequencies. Model : PE-W19PS1001, check website for more details.
Ferrite Microwave TechnologiesThe company offers high power waveguide phase shifters for different applications, check website for more.

Summary

Selecting the right waveguide phase shifting component requires a careful balance of performance metrics such as frequency range, insertion loss, power handling and physical form factor. The manufacturers listed above provide proven, high quality solutions trusted across industries.