Artificial Impedance Surface Antenna for Structural Blockage Mitigation
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Solution Overview
Problem
Conventional antennas on vehicles face interference and obstruction issues due to structural elements, which degrade radiation patterns and hinder RF reception and transmission, especially in areas with limited space for mounting and existing obstructions.
Innovation Solution
The use of artificial impedance surface antennas with spatially constant and non-constant impedance functions to mitigate obstruction effects by routing surface waves around interfering elements, utilizing a surface-wave waveguiding region to maintain radiation intensity and pattern integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional antenna is mounted on the vehicle body, then the antenna can transmit and receive RF signals, but structural elements (such as landing gear struts) block the radiation and degrade the radiation pattern
Solution Approach 1:
An artificial impedance surface is introduced as an intermediary between the conventional antenna and the obstructing structural element. This surface wave guide routes RF energy around the obstruction rather than allowing direct radiation that would be blocked, thereby maintaining reliable RF transmission and reception while avoiding radiation pattern degradation caused by the structural element
Solution Approach 2:
The patent replaces the conventional direct radiation mechanism with a surface wave propagation mechanism. Instead of relying on free-space radiation that is easily blocked by structural elements, the system uses guided surface waves that travel along the artificial impedance surface, substituting the radiation path to avoid mechanical obstructions
2Object-affected harmful factors
If the antenna position is moved to avoid obstructions, then radiation pattern may improve, but available mounting space is limited on the vehicle body
Solution Approach 1:
The patent segments the RF energy transmission path into two distinct regions: a first region with spatially constant impedance for surface wave propagation away from the antenna, and a second region with spatially non-constant impedance for radiating the surface waves into free space. This segmentation allows the antenna to remain in a limited mounting space while the artificial impedance surface extends the effective radiation path around obstructions
Solution Approach 2:
The patent transitions the RF energy transmission from a direct three-dimensional free-space radiation path to a two-dimensional surface wave propagation path along the artificial impedance surface. This dimensional change allows the system to work within the constrained mounting area while routing energy around obstructions in the third dimension through the surface guide
3Reliability
If the vehicle design is modified to remove obstructions, then RF reception may improve, but the vehicle structure cannot be changed after construction
Solution Approach 1:
The artificial impedance surface acts as a mediator that compensates for the inability to modify the vehicle structure. By introducing this passive surface wave guide, the system achieves improved RF signal reception around obstructions without requiring any changes to the existing vehicle design or structure
Solution Approach 2:
The patent changes the impedance parameters of the artificial impedance surface to create the desired surface wave propagation characteristics. By adjusting the spatial distribution of impedance values (constant in the first region, non-constant in the second region), the system optimizes surface wave guidance and radiation to mitigate obstruction effects without altering the vehicle's physical structure
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 minimizes attenuation caused by obstructions, maintaining radiation intensity and pattern consistency across a broad frequency range, with less than 1 dB reduction in radiation intensity even with significant obstructions like landing gear struts.
Implementation Method 1
emitting RF energy as surface waves on an artificial impedance surface from said feed point
Implementation Method 2
The artificial impedance surface has a first region with a first surface impedance function which supports said surface waves moving away from said feed point and a second region with a second surface impedance function which causes said surface waves to leak or launch off the artificial impedance surface
Implementation Method 3
a second region with a second surface impedance function which causes said surface waves to leak or launch off the artificial impedance surface as the radiation of said RF energy away from said artificial impedance surface
Data Source
AI summary
A method of and apparatus for mitigating adverse transmission and/or reception effects that an obstruction would otherwise have upon a RF signal to be transmitted or received, the RF signal being available at a feed point and wherein the obstruction is spaced from the feed point in a direction of desired transmission or reception. An artificial impedance surface is disposed adjacent the feed point and the obstruction, and the artificial impedance surface is designed (i) to have a spatially non-varying impedance function in a constant impedance region at least immediately adjacent the feed point and (ii) to have a non-constant impedance function in one or more regions spaced from the feed point and closer to the obstruction.