Patch Antenna Feed Structure for Symmetric Radiation
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Solution Overview
Problem
Existing patch antennas exhibit asymmetry in radiation patterns, limited gain, and bandwidth, particularly when used with small ground planes, which affects their directional characteristics and interference minimization in wireless communications systems.
Innovation Solution
A patch antenna design featuring a substantially square or circular patch radiator with feed points on opposite edges and transmission lines arranged between the patch radiator and ground plane, allowing for improved symmetry and phase control to reduce radiation pattern offset and enhance bandwidth, while maintaining a compact size and low manufacturing cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical patch antenna with a single feed point is used, then the structure is simple and easy to manufacture, but the radiation pattern shows asymmetry and the beam is offset from the desired direction
Solution Approach 1:
The single feed point is segmented into multiple feed points (at least two feed points on the patch radiator). This segmentation allows symmetric excitation of the patch edges, producing a symmetric radiation pattern with the beam directed normal to the ground plane, thereby resolving the asymmetry issue while maintaining manufacturing simplicity
Solution Approach 2:
Multiple feed points are combined with a common connection point through feed structures of different electrical lengths. This merging allows symmetric positioning of feed points on the patch while using unequal path lengths to achieve the desired phase relationship, resolving the contradiction between structural simplicity and radiation pattern symmetry
2Reliability
If the feed track connects to the patch antenna at a recessed point for improved impedance matching, then impedance matching is improved, but the path length to the feed point increases and complexity increases
Solution Approach 1:
The feed structures extend in different spatial dimensions or paths from the connection point to the feed points on the patch. By using feed structures with different electrical lengths (one longer than the other), the patent achieves both impedance matching and symmetric radiation patterns without requiring complex recessed feed points, thereby reducing overall device complexity
3Area of stationary object
If a ground plane of limited size is used, then the antenna size is reduced, but the radiation pattern shows asymmetry and gain is limited
Solution Approach 1:
The patent intentionally uses asymmetric feed structures (different electrical lengths) to achieve symmetric radiation patterns. By feeding the patch at multiple points with controlled phase differences through unequal path lengths, the system compensates for the limited ground plane size and achieves symmetric radiation characteristics without requiring a large ground plane
4Device complexity
If the path length from connection point to feed points is equal, then the feed structure is simple, but the radiation pattern offset cannot be reduced
Solution Approach 1:
The patent changes the electrical path length parameter of the feed structures, making one path longer than the other. This parameter change allows control over the phase relationship between signals at different feed points, enabling reduction of radiation pattern offset and improvement of beam direction while maintaining reasonable structural complexity
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 design achieves improved symmetry and reduced offset in radiation patterns, increased gain, and broader bandwidth, facilitating predictable directional characteristics and reduced interference in wireless communications systems.
Implementation Method 1
the patch radiator providing a resonant piece of microstrip transmission line capable of radiating from each edge of the patch radiator
Implementation Method 2
the first feed structure comprises at least a first transmission line arranged to connect the first of said feed points to the second of said feed points
Data Source
Figure 1
Figure 2A~2B
Figure 2C~3
AI summary
A patch antenna comprises a patch radiator (12), at least a first connection point (2a) for at least a first radio frequency signal, and at least a first feed structure (14). The first feed structure is arranged to connect the first connection point to at least two feed points on the patch radiator, a first of the feed points (4a) being disposed adjacent to a first edge (8a) of the patch radiator, and a second of the feed points (4b) being disposed adjacent to a second edge (8b) of the patch radiator, the first and second edges being on opposed sides of a central region of the patch radiator. The first feed structure comprises at least a first transmission line arranged to connect the first of the feed points to the second of the feed points, the transmission line being disposed in a substantially parallel relationship to the patch radiator.