Glide-Symmetric Waveguide Filters for Wide Stop-Band Rejection
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Solution Overview
Problem
Existing waveguide filters for mm-waves and submm-waves applications face challenges such as high manufacturing complexity and cost due to small metallic pin dimensions, limited stop-band rejection, and difficulty in achieving multiple pass-bands and stop-bands, particularly at high frequencies like 28 GHz and 60 GHz.
Innovation Solution
The design employs glide-symmetric unit cells with elements like holes or recesses on parallel metal plates, utilizing electromagnetic band gap surfaces to constrain electromagnetic waves, allowing for easy and cost-effective manufacturing and enabling flexible multiple pass-bands and stop-bands, low losses, and easy integration with existing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional waveguide filters are used at mm-waves, then low losses and high power handling capability are achieved, but manufacturing complexity and cost increase due to small dimensions and assembly accuracy requirements
Solution Approach 1:
The filter is divided into multiple unit cells, each with identical or similar structures. This segmentation allows for modular manufacturing where each unit cell can be fabricated separately and then assembled, reducing the overall manufacturing complexity while maintaining the low loss characteristics of traditional waveguide filters.
Solution Approach 2:
The invention changes the geometric parameters of the waveguide structure by introducing periodic modulations (such as ridges, grooves, or iris elements) along the waveguide path. These parameter changes create frequency-selective filtering characteristics without requiring complex assembly, thus reducing manufacturing complexity while maintaining low RF losses.
2Loss of energy
If traditional waveguide filters are used at mm-waves, then low losses are achieved, but manufacturing cost increases due to small dimensions and assembly accuracy requirements
Solution Approach 1:
By segmenting the filter into repeating unit cells, the manufacturing process can be simplified and standardized. Each unit cell can be manufactured using the same process and then assembled, reducing overall manufacturing cost despite the small dimensions required for mm-wave operation.
Solution Approach 2:
The periodic modulation of waveguide parameters provides frequency-selective filtering with simpler structures that are easier and less costly to manufacture compared to traditional complex waveguide filter designs at mm-wave frequencies.
3Object-generated harmful factors
If waffle iron filters are used, then good rejection of higher order modes is achieved, but manufacturing difficulty increases at mm-waves due to very small metallic pin dimensions
Solution Approach 1:
The invention uses periodic modulations of the waveguide parameters (such as ridge height, groove depth, or iris dimension) to achieve higher order mode rejection. This approach avoids the need for very small metallic pins required by waffle iron filters, making the structure easier to manufacture at mm-wave frequencies while maintaining good mode rejection characteristics.
4Ease of manufacture
If glide-symmetric unit cells are used, then cost-effective manufacturing is achieved, but filter design complexity increases to achieve multiple pass-bands and stop-bands
Solution Approach 1:
The glide-symmetric unit cells incorporate asymmetric elements that, when periodically repeated, create complex filtering characteristics including multiple pass-bands and stop-bands. The asymmetry in the unit cell design allows for tailored frequency responses while maintaining manufacturing simplicity through the repetitive nature of the structure.
Solution Approach 2:
By using periodic glide-symmetric unit cells, the filter achieves multiple pass-bands and stop-bands through the periodic modulation of the waveguide parameters. The periodic repetition of the unit cells creates a comb-like frequency response with multiple resonant frequencies, enabling complex filtering functionality with relatively simple manufacturing.
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 approach results in waveguide filters with large stop-bands to suppress out-of-band emissions, flexible multiple pass-bands, low losses, and cost-effective manufacturing, overcoming the limitations of traditional waveguide filters by using glide-symmetric structures that are easier to realize and integrate into mm-wave systems.
Implementation Method 1
electromagnetic band gap, EBG, surfaces on sides of the first and second plates to constrain the electromagnetic wave to propagate along a direction of the cavity
Implementation Method 2
as the electromagnetic wave is traversing about the elements in the cavity, specific wavelengths are filtered
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3~4
AI summary
A filter for filtering an electromagnetic wave and a filter design method are provided. The filter comprises a cavity with a first plate and a second plate, the first and second plates are opposite to each other. The first plate comprises a number of elements distributed on the side of the first plate facing the cavity, wherein a location of each element on the first plate is defined in a coordinate system. The second plate comprises a number of elements distributed on the side of the second plate facing the cavity according to the locations of the elements on the first plate, wherein each element is distributed on the second plate with an offset with respect to a corresponding element on the first plate.