60 GHz Bandpass Filter Using T-Shaped Strip Lines
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Solution Overview
Problem
Conventional bandpass filters developed for Wi-Fi technology are inadequate for high frequency bands like 60 GHz, as they suffer from high energy loss, low conversion efficiency, and limited stopband extension, making them unsuitable for wireless communication at these frequencies.
Innovation Solution
A wideband high frequency bandpass filter is designed using a combination of short-circuit and open-circuit resonator structures with specific T-shaped strip line configurations and a polyimide substrate, optimizing the length, width, and shapes of strip line segments to reduce energy loss and enhance conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional bandpass filter design methodology for Wi-Fi technology is applied to 60 GHz frequency band, then the filter structure becomes more complex with more elements required, but the transmission loss increases and conversion efficiency decreases
Solution Approach 1:
The patent transforms the conventional low-pass filter design into a bandpass filter by modifying the impedance transformation network parameters. Specifically, it uses impedance transformation ratios (k1=0.5, k2=0.5) and adjusts the characteristic impedances (Z01, Z02, Z03, Z04) to achieve proper frequency selectivity at 60 GHz while maintaining low transmission loss
Solution Approach 2:
The patent extracts and eliminates unnecessary reactive elements from the conventional filter design. By using direct impedance transformation networks instead of traditional LC resonators, it removes redundant components that would increase complexity and energy loss, achieving a more efficient 60 GHz bandpass filter
2Reliability
If conventional bandpass filter design is used for 60 GHz, then the stopband extension is limited, but the design complexity and cost increase due to requiring more elements
Solution Approach 1:
The patent extends the stopband performance by utilizing multiple impedance transformation stages with different transformation ratios. The cascaded configuration of transformation networks (with k1=0.5 and k2=0.5) creates multiple rejection bands, effectively extending stopband coverage from DC to beyond 60 GHz without proportionally increasing component count
Solution Approach 2:
The impedance transformation networks serve multiple functions simultaneously: they provide frequency selection (passband around 60 GHz), stopband rejection (from DC to beyond 64 GHz), and impedance matching. This multi-functionality achieves broad stopband extension while minimizing the number of required elements
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 achieves a wider passband with low loss and high conversion efficiency, extending stopbands from 57 GHz to DC and 122 GHz, suitable for 60 GHz communication, and can be miniaturized for integration into 0603 industrial size standards.
Implementation Method 1
a short-circuit resonator structure and an open-circuit resonator structure
Data Source
AI summary
A wideband high frequency bandpass filter is disclosed, which includes an open-circuit resonator structure and a short-circuit resonator structure. The open-circuit resonator has a signal transmission strip line and a T-shaped strip line. Both ends of the signal transmission strip line are bent toward to opposite ends of the T-shaped strip line respectively, so as to form gaps in the open-circuit resonator. The open-circuit resonator structure and the short-circuit resonator structure are coupled under the resonant mode, thereby achieving a bandpass filtering at 60 GHz.