Directional Patch Antenna Spacing for Broadband Pattern Stability
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Solution Overview
Problem
Broadband cross-polarized directional antennas face challenges in maintaining pattern stability and gain across a wide frequency range due to pseudo surface waves and undesirable EM interactions between metamaterial and conductive ground planes, leading to frequency limitations and increased manufacturing costs.
Innovation Solution
A broadband directional antenna design featuring a conductive non-circular patch antenna, active and passive dipole radiators, and a metamaterial ground plane assembly with a dielectric substrate and spaced conductive elements arranged in circular patterns, optimized for improved bandwidth, pattern consistency, and gain, with a larger patch surface area compared to the metamaterial ground plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a metamaterial ground plane is positioned between a radiator and a conductive ground plane to achieve broader bandwidth, then bandwidth is improved, but radiation pattern control becomes problematic due to pseudo surface waves and undesirable EM interactions
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the metamaterial ground plane and the active radiator, mediating the electromagnetic interactions to suppress pseudo surface waves while preserving the bandwidth enhancement benefits of the metamaterial structure
Solution Approach 2:
The ground plane assembly combines metamaterial elements with a dielectric substrate to create a composite structure that achieves both broad bandwidth and stable radiation patterns by leveraging the complementary properties of different materials
2Power
If the ideal spacing for a dipole radiator is set to a quarter wavelength above the reflector surface, then gain is improved at a specific frequency, but the antenna becomes frequency limited with destructive interference at twice the frequency
Solution Approach 1:
The spacing between the radiator and ground plane is optimized to a specific fraction (e.g., 0.05 to 0.15) of the wavelength rather than the traditional quarter wavelength, creating a configuration that maintains constructive interference across a broader frequency range and eliminates the destructive interference problem at harmonic frequencies
3Duration of action of moving object
If a broadband directional antenna with metamaterial layer is designed to achieve broad bandwidth, then bandwidth is improved, but the antenna becomes cumbersome and costly to manufacture and assemble
Solution Approach 1:
The metamaterial ground plane is designed with a reduced surface area relative to the radiating element, concentrating the metamaterial functionality in a localized region that provides the necessary bandwidth enhancement while reducing overall complexity and manufacturing cost
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 enhanced gain performance, particularly below 1 GHz and in the 3 GHz to 3.6 GHz range, with more stable radiation patterns and reduced manufacturing complexity, addressing the limitations of existing antennas.
Implementation Method 1
a metamaterial ground plane assembly located between the patch antenna and the at least one active radiator
Implementation Method 2
The metamaterial ground plane assembly may comprise a dielectric substrate with spaced conductive elements formed thereon
Data Source
AI summary
A broad band directional antenna 10 comprises a patch antenna 12 comprising a conductive and non-circular patch 14 and having a main axis 16 extending perpendicularly to the patch. The antenna further comprises at least one active radiator 18.1, 18.2 which is axially spaced from the patch 14 in a first direction A. A metamaterial ground plane assembly 20 is located between the patch antenna 12 and the at least one active radiator 18.1, 8.2. The patch antenna 12 comprises a conductive ground plane 22 which is axially spaced from the patch 14 in a second and opposite direction B.