Printed Broadband Absorber for RF Co-site Interference Mitigation
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Solution Overview
Problem
Co-site interference between co-located radio frequency systems on airborne and sea-based platforms, such as electronic warfare and radar systems, adversely affects the performance of on-board RF systems due to strong signal reception by nearby receivers despite the main beam being aimed away from them.
Innovation Solution
Incorporating a transmitter (TX) signal absorber and a receiver (RX) signal absorber, each comprising a printed broadband absorber (PBA) with broadband dual-polarized array cells and a ground plane, to absorb energy induced by RF signals, thereby mitigating electrical co-site interference between transmitters and receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple RF systems are co-located on airborne and sea-based platforms, then the system functionality and coverage are improved, but co-site interference between transmitters and receivers adversely affects system performance
Solution Approach 1:
A printed broadband absorber (PBA) is introduced as an intermediary component between the transmitter and receiver antenna arrays. The PBA includes a ground plane with periodic array cells containing resistive elements that absorb electromagnetic energy and convert it to heat, acting as a mediator that prevents direct interference between co-located RF systems while allowing both systems to operate simultaneously
Solution Approach 2:
The absorber structure changes the electromagnetic parameter distribution in the space between transmitter and receiver by introducing lossy resistive elements with specific impedance characteristics. The periodic array cells are designed with specific geometric parameters (element width, spacing, height) that create frequency-dependent absorption characteristics, transforming the electromagnetic environment to reduce interference
2Power
If a transmitter antenna array operates with high power, then the transmission capability is improved, but strong signals are received by nearby receivers even when the main beam is aimed away
Solution Approach 1:
The printed broadband absorber serves as an intermediary that intercepts and absorbs stray electromagnetic energy from high-power transmitter operations. The resistive array cells provide a controlled impedance path that converts unwanted RF energy to heat, preventing it from reaching nearby receivers while allowing the transmitter to operate at high power levels
Solution Approach 2:
The absorber converts the harmful stray electromagnetic energy from high-power transmission into beneficial heat energy through resistive dissipation. By providing a controlled absorption mechanism, the system transforms what would be interference into a harmless thermal effect, enabling high-power operation without compromising receiver sensitivity
3Area of stationary object
If RF systems operate in close proximity, then space utilization is improved, but electrical co-site interference reduces system reliability
Solution Approach 1:
The printed broadband absorber is positioned as a planar intermediary structure between co-located transmitter and receiver systems, absorbing electromagnetic energy in the near-field region. This allows compact co-location of RF systems while maintaining signal integrity and system reliability through active interference mitigation
Solution Approach 2:
The absorber introduces a two-dimensional planar structure (ground plane with periodic elements) that provides interference mitigation across a spatial region. By distributing absorption elements across a surface area rather than using a single point absorber, the system effectively manages interference in multiple spatial dimensions while maintaining compact form factor
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces co-site electrical interference by absorbing energy, allowing for improved performance and simultaneous operation of neighboring multi-function RF systems with shared or overlapping frequency bands, with the absorbers providing wideband attenuation and increased electrical signal isolation.
Implementation Method 1
Each array cell includes a plurality of conductive elements... An electrically conductive signal layer is configured to establish a matched terminated impedance of the plurality of broadband dual-polarized array cells that mitigates co-site electrical interference
Implementation Method 2
A ground plane is in signal communication with the plurality of broadband dual-polarized array cells. The ground plane is electrically coupled to a ground potential.
Data Source
AI summary
A radio frequency (RF) system includes a transmitter and a receiver. The transmitter includes a transmitter (TX) antenna array and a TX signal absorber. The TX antenna array is configured to output a first RF signal. The receiver includes a receiver (RX) antenna array and a RX signal absorber. The RX antenna array is configured to receive a second RF signal. The TX signal absorber and the RX signal absorber are each configured to absorb energy induced by the RF signal thereby mitigating electrical co-site interference between the transmitter and the receiver.