Microstrip RF Combiner Tapered Impedance Matching
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Solution Overview
Problem
Existing signal splitters, such as the Wilkinson Divider, are frequency-dependent and limited to narrow bandwidth applications due to their reliance on quarter-wavelength transformer elements, leading to poor performance in wideband or dual-band scenarios and increased insertion loss from balancing resistors.
Innovation Solution
A microstrip-based multiport splitter or combiner design that uses tapered sections to match impedance between ports without external components, providing isolation and wideband performance through phase cancellation and impedance transformation, allowing operation over a wider bandwidth without the need for discrete components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Wilkinson Divider is used for signal splitting, then impedance matching is achieved at a specific frequency, but bandwidth is limited to a narrow range
Solution Approach 1:
The patent transforms the fixed-impedance quarter-wavelength transformers into tapered transmission lines where the characteristic impedance varies continuously along the length. This parameter change allows the structure to maintain impedance matching across a wide frequency range rather than at a single frequency, resolving the contradiction between precise impedance matching and bandwidth limitation.
Solution Approach 2:
The tapered sections introduce dynamic variation in characteristic impedance along the transmission path, transitioning from a static impedance value to a continuously changing impedance profile. This dynamic impedance transformation enables the device to adapt to different frequencies within a wide bandwidth while maintaining proper impedance matching.
2Measurement precision
If balancing resistor is added to Wilkinson Divider, then impedance matching is improved, but insertion loss increases
Solution Approach 1:
The patent removes the balancing resistor from the Wilkinson Divider structure entirely. Instead of using a resistor to achieve impedance matching, the invention employs tapered transmission lines that provide impedance transformation through their geometric progression, eliminating the energy loss associated with resistive elements while maintaining proper impedance matching.
3Measurement precision
If quarter-wavelength transformer elements are used, then impedance transformation is achieved, but frequency dependence increases
Solution Approach 1:
The patent changes the parameter of characteristic impedance from a constant value to a continuously varying parameter along the transmission line. This transformation from fixed to variable impedance enables the structure to maintain effective impedance transformation across multiple frequencies, reducing frequency dependence while preserving the impedance transformation function.
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 microstrip design achieves greater than 30 dB isolation and operates over an octave and a half bandwidth with lower insertion loss, making it a cost-effective alternative to Wilkinson Dividers, suitable for RF devices operating in the GHz range and capable of dual-band operation.
Implementation Method 1
uses tapered sections to match impedance between ports without external components, providing isolation and wideband performance through phase cancellation and impedance transformation
Implementation Method 2
providing isolation and wideband performance through phase cancellation and impedance transformation
Data Source
AI summary
Disclosed is a radio-frequency divider comprising: an input port; and two output ports, separated by a bridge bar, wherein the divider is arranged in microstrip form and the microstrip structure takes the form of a generally tapering section connecting the input port to the bridge bar such that the input port is positioned at the relatively thinner end of the tapering section and the bridge bar is positioned at the relatively wider end of the tapering section. Also disclosed is a corresponding method. The divider is able to operate equally as a combiner.