Multiport Distribution Network Synthesis Using 180° Hybrid Couplers
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Solution Overview
Problem
Existing methods for synthesizing multi-port networks face limitations in defining polynomials for networks with more than 3 ports and the maximum number of couplings each resonator can sustain, leading to singularities in the coupling matrix and reduction of ports/resonators, especially when the transfer function does not exhibit single poles.
Innovation Solution
A method for synthesizing an N x N multiport distribution network with a filter transfer function using a 180° hybrid coupler based on resonators, which avoids the issue of multiplicity of roots by exploiting the virtual open circuit offered by the hybrid coupler, allowing for equal power distribution and proper phase distribution among outputs, and incorporating additional resonators to increase filtering selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional synthesis methods based on equivalent transversal networks and matrix rotations are used, then the circuit can be synthesized from rational polynomials, but singularities occur in the coupling matrix when the transfer function does not exhibit single poles, leading to reduction of ports/resonators
Solution Approach 1:
The patent segments the multiport network synthesis into independent path analyses. Instead of treating the entire network as a single complex system requiring full matrix rotation, the invention analyzes each path from input to output ports separately, defining transfer functions for individual paths. This segmentation avoids the singularity problem in the global coupling matrix while maintaining synthesis reliability.
Solution Approach 2:
The patent inverts the traditional synthesis approach by starting from the desired transfer function specifications and working backwards to determine the network configuration, rather than starting from the rational polynomial form and attempting to convert to the final topology. This reverse approach allows direct definition of coupling coefficients without encountering singularity issues in the matrix transformation process.
2Manufacturing precision
If the number of ports and resonators is increased to achieve higher selectivity, then filtering performance improves, but the complexity of defining polynomials and managing couplings increases beyond current method limitations
Solution Approach 1:
The patent applies segmentation by analyzing each path independently and defining transfer functions for individual paths rather than attempting to synthesize the entire multiport network simultaneously. This allows the network to be scaled to higher port counts and resonator numbers without exponentially increasing synthesis complexity, as each path can be designed using the same systematic approach.
Solution Approach 2:
The patent changes the fundamental parameters of the synthesis method by working directly with transfer function specifications and coupling coefficients rather than converting from rational polynomial forms. This parameter transformation enables the systematic design of networks with any number of ports and resonators, removing the practical limitations imposed by traditional matrix rotation methods.
3Ease of manufacture
If existing direct synthesis formulas are used for simple cases, then analytical solutions can be obtained, but these methods are not valid for multiplexing applications when the transfer function exhibits multiple poles
Solution Approach 1:
The patent creates a universal synthesis method that works for both simple cases with single poles and complex multiplexing applications with multiple poles. By defining transfer functions for each path and using a systematic approach to determine coupling coefficients, the invention provides a single unified methodology that adapts to any pole configuration, eliminating the need for separate analytical formulas for different cases.
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 enables the creation of multiport distribution networks with mutually isolated input ports, equal power distribution, and consistent phase distribution, while maintaining a same bandpass transfer function for all signals, and allows for increased filtering selectivity by adding resonators, thus overcoming the limitations of traditional techniques.
Implementation Method 1
a first resonator and a second resonator are coupled to each other... a third resonator and a fourth resonator are coupled to each other... the fifth resonator is coupled to the second resonator and to the fourth resonator
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A multiport distribution network is provided that supports N inputs and N outputs, where N>1, the multiport distribution network providing an independent distribution path extending from each input to each output, each path being formed from a sequence of at least two fundamental units. Each fundamental unit comprises a circuit formed of multiple resonator cavities and having n input ports for receiving respective input signals, and n output ports for outputting respective output signals, where n>1, and wherein the circuit is configured to: (i) at each input port, split an input signal received at that input port into n equal signal components and provide each of the n signal components to a respective output port of the circuit; and (ii) at each output port, combine the signal components received from the n input ports to form an output signal for that output port. The multiport distribution network is configured to apply the same filter transfer function along each independent distribution path.