Patch Antenna Cavity Reactance Surface Wave Suppression
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Solution Overview
Problem
Existing patch antennas face challenges in miniaturization due to the generation of surface waves, which are exacerbated by high permittivity substrates and the need for resonant cavities that restrict size reduction.
Innovation Solution
Incorporating a cavity with a reactance element that includes linear conductors connected to the ground conductive plate and extending towards the radiation electrode, allowing for electromagnetic resonance without requiring the cavity and radiation electrode to resonate together, thus suppressing surface wave generation and enabling size reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the permittivity of the dielectric substrate is increased to achieve size reduction, then the antenna size is reduced, but the bandwidth becomes narrow and surface wave generation is increased
Solution Approach 1:
A cavity structure is introduced as an intermediary between the radiation electrode and ground conductor plate. This cavity acts as a mediator that suppresses surface wave propagation while allowing the antenna to use high permittivity substrates for size reduction. The cavity walls reflect surface waves back into the cavity, preventing them from deforming the radiation pattern, thus resolving the contradiction between size reduction and maintaining reliable radiation characteristics.
Solution Approach 2:
The invention changes the electromagnetic parameters within the cavity by controlling the cavity dimensions and filling it with dielectric material. By adjusting the cavity height and introducing dielectric filling, the resonant frequency and impedance characteristics are modified to suppress surface waves at the operating frequency, thereby maintaining bandwidth and radiation pattern integrity while enabling high permittivity substrate usage.
2Reliability
If the thickness of the dielectric substrate is increased to widen the bandwidth, then the bandwidth is widened, but the possibility of surface wave generation is increased
Solution Approach 1:
The cavity structure serves as an intermediary that decouples the relationship between substrate thickness and surface wave generation. By introducing the cavity with conductive walls, surface waves are reflected and confined within the cavity region, preventing them from propagating along the substrate. This allows the substrate thickness to be increased for bandwidth widening without proportionally increasing surface wave generation, as the cavity walls act as barriers to surface wave propagation.
3Object-generated harmful factors
If a resonant cavity is used to suppress surface waves, then surface wave generation is suppressed, but the antenna size cannot be reduced due to cavity dimension constraints
Solution Approach 1:
The cavity structure is nested within the existing antenna architecture, utilizing the space between the radiation electrode and ground conductor plate. The cavity is formed by etching or removing material from the substrate, creating a recessed region that fits within the overall antenna footprint. This nested configuration allows the cavity to suppress surface waves without significantly increasing the external dimensions of the antenna, enabling miniaturization while maintaining surface wave suppression functionality.
Solution Approach 2:
The invention optimizes the cavity parameters (height, width, and dielectric filling) to achieve surface wave suppression at the operating frequency with minimal cavity volume. By carefully selecting the cavity height and dielectric constant of the filling material, the resonant frequency of the cavity is tuned to match the operating frequency, maximizing surface wave suppression efficiency while minimizing the cavity dimensions and overall antenna size.
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
This configuration effectively suppresses surface wave propagation, avoids bandwidth narrowing, and allows for flexible cavity dimensions, resulting in a smaller antenna size while maintaining good radiation characteristics.
Implementation Method 1
defining a cavity that causes electromagnetic resonance to occur
Data Source
AI summary
A surface-layer conductive plate having an opening is disposed on a first surface of a dielectric substrate. A radiation electrode is disposed inside the opening on the first surface of the dielectric substrate. A ground conductive plate is disposed on a second surface of the dielectric substrate, the second surface being opposite to the first surface. Interlayer connection members are disposed so as to surround the opening as seen in a plan view. The interlayer connection members electrically connects the surface-layer conductive plate to the ground conductive plate and defines a cavity that causes electromagnetic resonance to occur. A reactance element is configured to cause an impedance that a side face of the cavity exhibits with respect to an electromagnetic wave propagating in the cavity to include a reactance component.