Planar Antenna Surface Wave Reduction via Groove-Defined Virtual Walls
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Solution Overview
Problem
Classical patch antennas integrated into PCB structures suffer from substrate waves that interfere with neighboring antenna elements, degrading radiation performance due to sensitivity to the overall PCB structure and nearby objects.
Innovation Solution
A planar antenna structure with continuous grooves forming slots in the electrically conducting surface, creating a virtual electric wall that reduces surface wave propagation, thereby improving radiation performance by minimizing unwanted scattered fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If antennas are integrated into PCB structures, then integration density and compactness are improved, but surface wave propagation increases causing interference and degraded radiation performance
Solution Approach 1:
The patent introduces an electromagnetic bandgap (EBG) structure as an intermediary element between the antenna and the PCB ground plane. This EBG structure acts as a mediator that selectively blocks surface wave propagation while allowing the antenna to maintain its integrated PCB mounting. The EBG unit cells are positioned at specific locations on the PCB to create stopbands that prevent surface wave interference without compromising the compact integration.
Solution Approach 2:
The patent modifies the electromagnetic parameters of the PCB structure by introducing periodic EBG unit cells with specific geometric parameters (cell size, metal trace dimensions, substrate height). By carefully controlling these parameters, the EBG structure creates frequency-selective surface wave suppression. The periodic arrangement and dimensional parameters of the EBG cells are optimized to create stopbands at the operating frequencies, thereby changing the electromagnetic propagation characteristics of the PCB structure.
2Device complexity
If surface wave propagation is allowed, then antenna structure simplicity is maintained, but radiation performance deteriorates due to scattered field interference
Solution Approach 1:
The patent segments the continuous PCB ground plane by introducing periodic EBG unit cells that create discrete electromagnetic barriers. Instead of modifying the entire PCB structure uniformly, the EBG elements are strategically placed in specific regions where surface wave interference occurs. This segmentation approach maintains the overall simplicity of the PCB antenna structure while locally introducing complexity only where needed for surface wave suppression.
3Reliability
If EBG structures are added to suppress surface waves, then radiation performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the EBG surface wave suppression function with the existing PCB antenna structure by integrating the EBG unit cells directly into the PCB fabrication process. The EBG metal traces are formed using the same PCB manufacturing techniques (copper etching, lamination) as the antenna elements and ground plane, eliminating the need for separate manufacturing steps. This merging approach allows standard PCB manufacturing processes to produce both the radiating elements and the EBG suppression structures in a single fabrication run.
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 introduction of grooves significantly reduces surface wave propagation, enhancing antenna radiation performance and stability by creating a continuous electromagnetic wall that suppresses interference from nearby structures and objects.
Implementation Method 1
Each groove is defined by an at least virtual electric wall that is electrically connected to the surface structure and forms a continuous electromagnetic wall in the surface structure at the working frequency band such that propagation of surface waves via the at least one groove is reduced
Data Source
AI summary
The present disclosure relates to a planar antenna structure (100, 200, 800, 900) comprising at least one radiating aperture (101, 201 801, 901), adapted for a certain working frequency band, and an electrically conducting surface structure (102, 202, 802, 902) that is constituted by at least one surface part and is surrounding at least one radiating aperture (101, 201, 801, 901) and having a certain extension (T). The planar antenna structure (100, 200, 800, 900) comprises at least one continuous groove (103, 104; 203, 204; 803, 804; 903, 904) that forms a slot in the surface structure (102, 202, 802, 902), where each groove (103, 104) is defined by an at least virtual electric wall that is electrically connected to the surface structure (102, 202, 802, 902) and forms a continuous electromagnetic wall in the surface structure (102, 202, 802, 902) at the working frequency band. In this manner, that propagation of surface waves via the at least one groove (103, 104; 203, 204; 803, 804; 903, 904) is reduced.