Quad-Feed SIW Antenna for Dual Circular Polarization Coupling
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Solution Overview
Problem
Existing transmission line systems, particularly rectangular waveguides, face challenges in rotary joint applications due to electric field discontinuations and inability to support simultaneous bi-directional communication, and SIW transitions are needed to efficiently couple energy between different transmission mediums like microstrips and waveguides.
Innovation Solution
A substrate integrated waveguide (SIW) transition with dual or quad feeds and circular polarizations is designed to enable efficient energy coupling and bi-directional communication between PCB transmission lines and waveguides, using a dielectric substrate and metallic layers with via-holes and impedance transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rectangular waveguides are used in rotary joint applications, then electromagnetic energy can be transmitted, but electric field discontinuations occur and bi-directional communication cannot be achieved
Solution Approach 1:
The waveguide is segmented into multiple feeds (dual or quad feeds) with different polarization orientations. Each feed handles a specific polarization component, allowing independent signal paths for bidirectional communication without electric field discontinuation. The segmentation of the waveguide cross-section into distinct feed regions enables simultaneous transmission and reception.
Solution Approach 2:
The invention transitions from traditional single-mode rectangular waveguide to multi-feed configuration utilizing polarization diversity. By adding the polarization dimension as an additional degree of freedom, the system achieves bidirectional communication capability while maintaining electric field continuity through proper polarization alignment and isolation between feeds.
2Loss of energy
If traditional transmission line coupling is used between microstrips and waveguides, then energy transfer is achieved, but coupling efficiency is insufficient
Solution Approach 1:
The invention introduces substrate integrated waveguide (SIW) transitions as an intermediary structure between microstrip transmission lines and the main waveguide. The SIW transition includes dielectric substrates with metallic via-holes that provide gradual impedance transformation and efficient energy coupling, reducing reflection losses and improving overall coupling efficiency between different transmission mediums.
Solution Approach 2:
The coupling efficiency is improved by optimizing key parameters of the SIW transition structure, including dielectric substrate thickness, via-hole diameter and spacing, metallic layer thickness, and feed positioning. These parameter adjustments enable impedance matching and minimize coupling losses between microstrip and waveguide sections.
3Ease of operation
If single polarization feeds are used, then结构简单 (structure is simple), but simultaneous bi-directional communication is not supported
Solution Approach 1:
The waveguide structure is designed with dual or quad feeds that can simultaneously handle multiple polarization modes (horizontal, vertical, and circular polarizations). This multi-functional design allows a single waveguide structure to support bidirectional communication, MIMO operations, and different modulation schemes, reducing the need for separate dedicated structures for each function.
Solution Approach 2:
The feed structure incorporates adjustable and reconfigurable elements that can dynamically switch between different polarization modes and communication directions. This dynamic capability allows the system to adapt to different operational requirements (unidirectional/bidirectional, different polarizations) without requiring physically different structures, managing complexity through software-controlled reconfiguration.
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 SIW transition facilitates low-loss, bi-directional communication by decoupling electromagnetic fields with circular polarizations, allowing efficient propagation of electromagnetic energy in rotary joint applications and other systems like radar and lidar systems.
Implementation Method 1
a set of metallic via-holes positioned proximate the non-conductive opening in the second metallic layer. The set of metallic via-holes electrically couple the second metallic layer to the third metallic layer
Implementation Method 2
A second metallic layer is coupled to the top surface of the dielectric layer. The second metallic layer includes a non-conductive opening, a plurality of feeds each with a first end located in the non-conductive opening and a second end of each feed including a single-ended termination, and an impedance transformer
Implementation Method 3
Such SIW transitions can include four feeds with dual polarizations configured to concurrently provide the signals for transmission by the antenna structure and receive signals from the antenna structure for subsequent processing
Data Source
AI summary
Example embodiments relate to a substrate integrated waveguide (SIW) with dual circular polarizations. An example SIW may include a dielectric substrate and a first metallic layer coupled to a top surface of the dielectric substrate with a through-hole extending through the dielectric substrate and the first metallic layer. The SIW also includes a dielectric layer coupled to a top surface of the first metallic layer. A second metallic layer is coupled to a top surface of the dielectric layer. The second metallic layer includes a non-conductive opening, a plurality of feeds with a first end in the non-conductive opening and a second end including a single-ended termination, and an impedance transformer. The SIW also includes a third metallic layer coupled to a bottom of the dielectric substrate, and a set of metallic via-holes proximate the non-conductive opening and coupling the second metallic layer to the third metallic layer.