Coaxial to Planar RF Transition via Parallel Plate Waveguide
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Solution Overview
Problem
The transition between vertical and horizontal radio frequency propagation paths in circuit boards is inefficient due to mismatched transitions, inductive discontinuities, high insertion loss, and poor return loss, which existing solutions have not adequately addressed.
Innovation Solution
A coaxial transition design featuring a first conductor with a surrounding ground shield, a second conductor coupled to the first, and a top ground plane, creating parallel gaps that allow electric fields to radiate efficiently between conductors and shields, minimizing inductive breaks and maintaining a continuous transmission line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional coaxial transition structure is used, then the transition between vertical and horizontal RF propagation paths is achieved, but inductive discontinuities occur causing high insertion loss and poor return loss
Solution Approach 1:
The transition structure is segmented into distinct regions: a vertical coaxial section, a transition section with parallel plate waveguide geometry, and a horizontal microstrip section. This segmentation allows each section to be optimized for its specific function, eliminating inductive discontinuities at the transition point by maintaining continuous current paths through the parallel plate configuration.
Solution Approach 2:
The invention transitions from a three-dimensional coaxial structure to a two-dimensional parallel plate waveguide structure in the transition section. This dimensional change allows the electric field to be confined between parallel plates, creating a controlled impedance transition that eliminates inductive effects while maintaining RF signal integrity.
2Loss of energy
If smaller external vertical coaxial features are used to reduce inductive parasitic, then inductive parasitic is reduced, but manufacturing complexity increases and component size is constrained
Solution Approach 1:
The invention changes the geometric parameters of the transition structure by using a parallel plate configuration with controlled plate separation distance. This parameter change allows the transition section to function as a parallel plate waveguide, eliminating inductive parasitic effects without requiring smaller component sizes or more complex manufacturing processes.
3Reliability
If capacitance compensation is applied on the center conductor, then return loss is improved, but the structure becomes more complex and insertion loss increases
Solution Approach 1:
The invention extracts the capacitive compensation function from the center conductor and replaces it with a geometric configuration of parallel plates. By taking out the need for additional capacitive elements and using the parallel plate waveguide structure itself to provide the necessary electrical characteristics, the design achieves improved return loss without adding complexity or increasing insertion loss.
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 design enables more efficient RF signal transition with reduced insertion loss and improved return loss compared to traditional coaxial transitions, allowing for larger diameter components and easier manufacturing while maintaining efficiency across various RF frequencies.
Implementation Method 1
An electric field radiates between the first conductor and the ground shield through the first gap
Implementation Method 2
A first portion of the electric field radiates between the second conductor and the ground shield through the second gap
Data Source
AI summary
A coaxial transition includes a first conductor aligned along a first axis. The transition also includes a ground shield surrounding the first conductor such that a first gap exists between the first conductor and the ground shield. An electric field radiates between the first conductor and the ground shield through the first gap. The transition further includes a second conductor aligned along a second axis and coupled to the first conductor. The second conductor forms a second gap between the second conductor and a portion of the ground shield. A first portion of the electric field radiates between the second conductor and the ground shield through the second gap. The transition also includes a top ground plane aligned substantially parallel to the second conductor. A third gap exists between the top ground plane and the second conductor. The second gap and the third gap are substantially parallel with the second conductor therebetween.