Bandgap Impedance Surface for Compact Waveguide Transition
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Solution Overview
Problem
Current coaxial to waveguide transition modules require a quarter wavelength back short, leading to undesirable thickness and increased manufacturing complexity and cost, especially in phased array antenna applications where compactness is crucial.
Innovation Solution
The use of a bandgap surface comprising a ground plane, capacitive layers, and electrically conductive vias, along with dual frequency impedance surfaces and conductive elements, allows for compact construction and efficient signal transition between TEM and TE wave modes within a tubular waveguide structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a quarter wavelength back short is used in coaxial to waveguide transition modules, then the transition between TEM and TE wave modes is achieved, but the module height increases to exceed 0.450 inch
Solution Approach 1:
The patent changes the electrical parameters by introducing a high impedance surface with specific capacitance values (e.g., 0.05 pF to 0.50 pF) and inductance values (e.g., 0.01 nH to 0.10 nH) that create an artificial quarter wavelength transformation. This allows the physical height to be reduced while maintaining the electrical quarter wavelength function through impedance transformation rather than physical length alone.
Solution Approach 2:
The patent transitions from a one-dimensional physical length solution (quarter wavelength back short) to a two-dimensional solution by introducing a high impedance surface with distributed capacitance and inductance elements. The high impedance surface creates electromagnetic coupling that provides the quarter wavelength transformation in a planar structure rather than requiring increased vertical height.
2Ease of manufacture
If a quarter wavelength back short is used, then waveguide transition function is provided, but manufacturing complexity increases due to epoxy bonding of separate wiring boards
Solution Approach 1:
The patent merges the high impedance surface, capacitive elements, inductive elements, and waveguide transition structure into a single integrated planar module. This eliminates the need for separate wiring boards and epoxy bonding processes, reducing manufacturing complexity while maintaining the quarter wavelength transformation function.
Solution Approach 2:
The high impedance surface structure serves multiple functions simultaneously: it provides the quarter wavelength transformation, creates the necessary impedance transformation, and enables the waveguide mode transition. This multi-functionality in a single structure reduces the number of separate components and assembly steps required.
3Adaptability or versatility
If a quarter wavelength back short is used, then the transition module can be constructed, but the final stackup height exceeds 0.450 inch which is undesirable for phased array antenna applications
Solution Approach 1:
The patent changes the electrical parameters by using high impedance surfaces with specific capacitance (0.05-0.50 pF) and inductance (0.01-0.10 nH) values to create an artificial transmission line with effective quarter wavelength transformation. This allows the physical dimensions to be reduced while maintaining the electrical performance required for phased array antenna applications.
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 solution enables a significantly more compact waveguide transition module with reduced manufacturing complexity and cost, while maintaining high impedance and efficient signal transition performance, suitable for phased array antenna applications.
Implementation Method 1
a bandgap surface for use in a transition module. The surface may comprise: a ground plane; a capacitive layer including a plurality of capacitive elements arranged in a polar configuration within a common plane, and spaced apart from the ground plane; and a plurality of electrically conductive vias formed within a dielectric layer of material that conductively couple the ground plane to each of the capacitive elements
Implementation Method 2
a first impedance surface forming a plane, and adapted to resonate at a first frequency; and a second impedance surface placed within a void in the first impedance surface so as to be disposed within the plane and circumscribed by the first impedance surface, the second impedance surface being adapted to resonate at a second frequency different than the first frequency
Data Source
AI summary
A bandgap surface for use in a waveguide transition module. The surface may be constructed with a ground plane; a capacitive layer including a plurality of capacitive elements arranged in a polar configuration within a common plane, and spaced apart from said ground plane; and a plurality of electrically conductive vias formed within a dielectric layer of material that conductively couple said ground plane to each of said capacitive elements.