Planar RF Passband Filter With Resistive Loading for Flat Response
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Solution Overview
Problem
Existing radio frequency pass-band filters face challenges in achieving flatness across the passband and high insertion loss due to the finite Q factor of resonators, which complicates filter design and increases system complexity and cost.
Innovation Solution
A radio frequency pass-band filter is designed using a network of half-wavelength planar resonators, where at least one resonator includes a resistor shunted to ground to increase damping and flatten the response in the passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonators with finite Q factor are used in filter implementation, then the filter can be physically realized, but the transmission parameter lacks flatness across the passband and insertion loss increases
Solution Approach 1:
The patent changes the Q factor parameter of the resonators by introducing resistive loading. Specifically, resistors are connected in parallel with selected resonators to deliberately reduce their Q factor from high values to lower values, which compensates for the natural roll-off effects and achieves flat passband response. This parameter modification allows physical implementation while maintaining desired transmission characteristics.
2Reliability
If resonators with finite Q factor are used in filter implementation, then the filter can be physically realized, but insertion loss increases
Solution Approach 1:
The patent modifies the Q factor parameter through resistive loading to optimize the balance between physical realizability and energy loss. By carefully selecting resistor values for parallel connection with specific resonators, the design achieves acceptable insertion loss levels while ensuring the filter can be physically constructed with real-world components that have finite Q factors.
3Ease of manufacture
If classical lossless synthesis procedure is used, then the resonant frequency and coupling can be defined, but the model departs from practical filter implementation due to material losses
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-positioning resistive loading elements during the design phase to compensate for anticipated material losses. The resistors are strategically placed in parallel with specific resonators based on preliminary analysis of where losses will occur, allowing the practical filter to match the idealized synthesis model more closely despite real-world dissipative effects.
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 proposed solution effectively reduces the reflected signal and achieves a flatter response across the passband, while maintaining a compact and straightforward physical implementation, thus addressing the limitations of existing filter technologies.
Implementation Method 1
at least one of the half-wavelength planar resonators includes a resistor shunted to ground to increase damping and flatten the response in the passband
Implementation Method 2
A significant parameter for describing such a resonator is its Quality (Q) factor... which is defined as the ratio of the stored energy with the resonator divided by the amount of energy lost per cycle
Data Source
AI summary
A radio frequency passband filter is provided comprising a network of half-wavelength planar resonators. At least one of the half-wavelength planar resonators includes a resistor shunted to ground to flatten response in the passband.