Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras

Polarization-independent Frequency Selective Surfaces for Atmospheric Remote Sensing

Technology Category/Market

Category – Atmospheric Remote Sensing

Applications- Radiometers, Spatial filters, phase and control metasurfaces, Satellite based weather forecasting and monitoring

Industry- Remote Sensing, Radar Systems, Satellite Communication

Market The global remote sensing technology market size and is expected to hit around USD 55.36 billion by 2032, representing a CAGR of 11.79% from 2023 – 2032.


Problem Statement

  • Remote sensing radiometers require Frequency Selective Surfaces (FSS) to filter and demultiplex incoming electromagnetic (EM) waves within a wide frequency range (22–230 GHz) for weather monitoring.
  • FSSs need to be designed to be insensitive to the polarization and angle of incidence of the EM plane waves to effectively capture and route spectral emissions.
  • Current radiometers require FSS designs with characteristics such as insensitivity to polarization, wide operational bandwidth, and flexibility in accommodating various angles of incidence of EM plane waves.


  • The invention discloses frequency selective surface (FSS) unit cells that are capable of de-multiplexing the ultralow-power polarized plane wave from the earth’s atmosphere.
  • A miniaturized resonant FSS unit cell with angle and polarization stable frequency response is disclosed.
  • The unit cell includes a corner convoluted square ring that has parasitic patches on the four sides and is coupled to a cross dipole at the centre.
  • The unit cell rejects 50- 60 GHz and 170–195 GHz and transmits 87- 91 GHz. Further, a quadband millimeter wave frequency FSS unit cell that has a circular metal mesh loaded with a monopole integrated concentric ring on a quartz substrate is disclosed.
  • The unit cell is cascaded and is capable of rejecting bandwidths in the range 50–60 GHz, 87–91 GHz, and 148–151 GHz, and transmitting in the range 175–195 GHz. The FSS may be used in atmospheric remote sensing.

Key Features/Value Proposition

  • Miniaturized FSS Unit Cell: This invention presents a compact unit cell for Frequency Selective Surfaces (FSS) designed to manipulate millimeter wave signals.
  • Reflect and Transmit: The unit cell selectively reflects specific signal portions while substantially transmitting the rest of the incident millimeter wave signal.
  • Metal Ring Structure: It features a metal layer forming a connected four-sided ring structure with uniform trace widths.
  • Symmetric Dipole Structure: Inside the ring, a symmetric dipole structure with four arms is positioned at a specific distance from each side.
  • Mutual Coupling: When interacting with an incident millimeter wave signal, the unit cell allows mutual coupling between the ring and dipole structures, enabling precise signal reflection and transmission..
Questions about this Technology?

Contact for Licensing

Research Lab

Prof. Kavitha Arunachalam

Department of Engineering Design

Prof. C.V. Krishnamurthy,

Department Of Physics

Intellectual Property

  • IITM IDF Ref. 1669
  • IN 373105 – Patent Granted

Technology Readiness Level

TRL – 4

Technology validated in lab scale.

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