Artificial Impedance Surface Antenna Steering via Segmented Varactors
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Solution Overview
Problem
Current two-dimensional electronically-steerable artificial impedance surface antennas are costly and complex due to the need for complex voltage control networks and vias, which reduce operational bandwidth and limit tunability, making them less desirable for applications requiring low-cost and simple solutions.
Innovation Solution
An antenna system comprising a plurality of radiating elements with surface wave channels and switch elements on a dielectric substrate, where each radiating element includes impedance elements and tunable elements, allowing for electronic steering in two dimensions by controlling the surface wave impedance through voltage applied to varactors or switch elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex voltage control network is used to achieve two-dimensional electronic steering, then the steering capability is improved, but the device complexity and cost increase
Solution Approach 1:
The antenna surface is segmented into multiple independent impedance elements arranged in a two-dimensional array, where each element can be controlled by a simple voltage line. This segmentation allows the complex steering function to be achieved through simple individual element control rather than a complex interconnected control network.
Solution Approach 2:
Each impedance element in the array serves multiple functions: it contributes to the overall radiation pattern, enables electronic beam steering, and can be independently tuned. This multi-functionality allows a simple uniform array structure to achieve complex two-dimensional steering without requiring specialized control mechanisms for each element.
2Stability of the object's composition
If vias are used to connect patches to ground plane and voltage sources, then the structural integrity is improved, but the operational bandwidth is reduced
Solution Approach 1:
The harmful inductive effect of vias is extracted and eliminated by replacing the via-based connection system with a surface-mounted capacitor system. The capacitors are placed directly on the antenna surface between adjacent patches, removing the need for vias to pass through the substrate and thereby eliminating the bandwidth-limiting inductance while maintaining structural integrity through alternative mounting methods.
Solution Approach 2:
Capacitors are introduced as intermediary elements to provide the necessary electrical connections and impedance control between patches without requiring vias. These surface-mounted capacitors act as mediators that achieve the same electrical function as vias but without the harmful inductive side effects, thereby expanding operational bandwidth.
3Adaptability or versatility
If varactors are tuned to higher capacitance to control impedance, then the impedance tuning range is improved, but the surface wave bandgap frequency decreases
Solution Approach 1:
The invention changes the approach to impedance control by using fixed capacitors with carefully selected values rather than continuously variable varactors. By selecting specific capacitor values that provide the required impedance transformation, the system achieves the necessary impedance tuning range without the harmful effect of increasing overall capacitance that would lower the bandgap frequency.
Solution Approach 2:
Different fixed capacitor values are applied at different locations in the antenna array based on the specific impedance requirements of each position. This local optimization allows each element to achieve the required impedance matching without collectively increasing the total capacitance that would lower the surface wave bandgap frequency.
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 proposed solution enables efficient electronic steering in two dimensions with reduced complexity and cost, improving the operational bandwidth and tunability of the antenna system, making it more suitable for various applications.
Implementation Method 1
A varactor is a semiconductor element diode that has a capacitance dependent on the voltage applied to this diode
Implementation Method 2
An artificial impedance surface antenna may be implemented by launching a surface wave across an artificial impedance surface
Data Source
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AI summary
A method and apparatus for electronically steering an antenna system is provided. A surface wave is propagated along each of a number of surface wave channels formed in each of a plurality of radiating elements to form a radiation pattern. Each surface wave channel in the number of surface wave channels formed in each radiating element in the plurality of radiating elements is coupled to a transmission line configured to carry a radio frequency signal using a surface wave feed in a plurality of surface wave feed associated with the plurality of radiating elements. A main lobe of the radiation pattern is electronically steered by controlling voltages applied to a plurality of switch elements connecting a plurality of impedance elements in each of the number of surface wave channels.