Patch Antenna Assembly with Capacitive Feed Points and Shielding Vias
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Solution Overview
Problem
Microstrip patch antennas have limited radiation bandwidth and gain, and their asymmetric radiation patterns due to thick substrates and feed probe radiation issues hinder their broadband application.
Innovation Solution
The design includes a symmetric patch antenna with dual capacitive feed points and feed lines providing non-quadrature phasing, coupled with phase delay circuitry and conductive shielding vias to enhance bandwidth, gain, and radiation pattern symmetry, while bucking openings and vias reduce undesirable radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the substrate thickness is increased to broaden the operational frequency range, then the bandwidth is improved, but the feed probe radiates like a monopole antenna causing asymmetric radiation patterns and reduced gain
Solution Approach 1:
The patent extracts and removes the harmful monopole radiation from the feed probe by using conductive shielding vias that surround the feed probe and are connected to the ground plane. These vias create a shielded environment that prevents the feed probe from radiating independently, thereby eliminating the asymmetric radiation pattern while maintaining the broadband performance enabled by the thick substrate.
Solution Approach 2:
The patent introduces conductive shielding vias as an intermediary element between the feed probe and the external environment. These vias act as a mediator that blocks the harmful monopole radiation from the feed probe while allowing the desired patch antenna radiation to proceed, thus resolving the contradiction between bandwidth enhancement and radiation pattern symmetry.
2Device complexity
If conventional single feed probe is used, then the structure is simple, but the radiation bandwidth is limited to less than 20 percent
Solution Approach 1:
The patent segments the single feed probe into multiple feed probes arranged in a specific geometry (e.g., tetrahedral configuration). This segmentation allows each feed probe to contribute to different polarization components, thereby expanding the operational bandwidth while maintaining relative structural simplicity through the use of identical repeated elements.
Solution Approach 2:
The patent employs a composite feeding structure that combines multiple feed probes with a thick substrate and conductive shielding vias. This composite approach integrates the benefits of multiple feeding points for bandwidth expansion with the shielding mechanism for pattern control, achieving broadband performance without excessive complexity.
3Duration of action of moving object
If thick substrate is used to increase bandwidth, then the bandwidth increases linearly, but the feed probe radiation creates reduced realized gain
Solution Approach 1:
The patent converts the harmful effect of feed probe monopole radiation into a beneficial shielding mechanism. By surrounding the feed probe with conductive vias connected to ground, the previously harmful radiation is contained and redirected, allowing the thick substrate to provide bandwidth enhancement without the penalty of reduced realized gain from asymmetric patterns.
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 increases bandwidth, gain, and directivity, achieving a more symmetric radiation pattern and improved efficiency by counteracting feed line radiation, resulting in a broader operational frequency range and enhanced performance.
Implementation Method 1
first and second feed pads in the first and second feed openings, respectively, defining first and second capacitive feed points
Implementation Method 2
a plurality of spaced apart conductive shielding vias coupled to the ground plane and extending through the substrate surrounding the electrically conductive patch antenna element
Implementation Method 3
a phase delay circuitry carried by the substrate and coupled to the first and second feed lines. The phase delay circuitry (51) is configured to provide non-quadrature phasing between the first and second feed lines
Data Source
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AI summary
An electronic device may include wireless communications circuitry and an antenna assembly coupled thereto. The antenna assembly may include a substrate, an electrically conductive layer defining a ground plane carried by the substrate, and an electrically conductive patch antenna element carried by the substrate and spaced from the ground plane. The patch antenna element may have a symmetric axis dividing the patch antenna element into first and second symmetric areas, and first and second feed openings in the first and second symmetric areas, respectively. The antenna assembly may also include first and second feed pads in the first and second feed openings, respectively, and first and second feed lines extending through the substrate and respectively coupling the feed pads to the wireless communications circuitry. Spaced apart conductive shielding vias may be coupled to the ground plane and may extend through the substrate surrounding the patch antenna element.