Planar Antenna Using Thin Dielectric Layer for Low Profile
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Solution Overview
Problem
Planar antennas with single or multiple polarizations face challenges in achieving a low profile design while maintaining large frequency bandwidth and minimizing cross-polarization and interference issues, particularly in applications where a quarter wavelength metallic cavity is not feasible.
Innovation Solution
A planar antenna configuration featuring a signal path, a conductive layer with a slot, a dielectric layer separating the slot from a conductive plate, and patches above the plate, eliminating the need for a quarter wavelength cavity by using a thin dielectric layer and orthogonal slots for dual polarization, which directs radiation upwardly and provides excellent cross-polarization characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quarter wavelength metallic cavity is used to reflect downward radiation, then radiation interference is prevented and radiation strength is increased, but antenna height becomes too large for low profile applications
Solution Approach 1:
The patent extracts and eliminates the quarter wavelength metallic cavity from the antenna structure. Instead of using a deep cavity to reflect downward radiation, the invention uses a thin dielectric layer with conductive plates to achieve the same radiation control function with minimal height, thus resolving the contradiction between preventing radiation interference and maintaining low profile.
Solution Approach 2:
The patent changes the physical parameters of the radiation reflecting structure. Instead of using a metallic cavity with depth equal to one-quarter wavelength, the invention uses a dielectric layer with thickness much smaller than one-quarter wavelength (e.g., 0.01 to 0.1 wavelengths), fundamentally changing the scale and dimension of the structure to achieve low profile while maintaining functionality.
2Adaptability or versatility
If slot coupling is used to achieve wide bandwidth, then frequency bandwidth is increased, but downward radiation causes interference with other antennas and circuits
Solution Approach 1:
The patent converts the harmful downward radiation from the slot into a beneficial effect. By placing a conductive plate below the thin dielectric layer, the downward radiation is reflected upward and constructively interferes with the main radiation, enhancing the radiation strength in the desired direction while eliminating interference with other antennas and circuits.
3Length of stationary object
If proximity coupling or L-probe coupling is used to reduce height, then antenna height is reduced, but cross polarization performance deteriorates
Solution Approach 1:
The patent introduces a thin dielectric layer as an intermediary between the slot and the conductive plate. This dielectric layer enables effective coupling and radiation control while maintaining excellent cross-polarization performance, resolving the contradiction between low height and good cross-polarization characteristics that plagues proximity coupling and L-probe coupling methods.
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 solution results in a compact, high-bandwidth antenna with improved cross-polarization and reduced interference, suitable for applications requiring a low profile, such as automotive and space-based radars, with estimated bandwidths of 25% or greater and excellent isolation between polarizations.
Implementation Method 1
a conductive layer having a slot formed therein positioned to electromagnetically couple with the signal path
Implementation Method 2
a dielectric layer separating the slot from a conductive plate
Implementation Method 3
directs radiation upwardly and provides excellent cross-polarization characteristics
Data Source
AI summary
A planar antenna comprising a signal path for receiving or transmitting a signal, a conductive layer having a slot formed therein positioned to electromagnetically couple with the signal path, a conductive plate parallel to and overlying the slot and spaced therefrom by a dielectric layer, the conductive plate being electrically in contact with the signal path, and one or more patches parallel to and above the conductive plate.