Liquid Crystal Phase Shifter Electrode Layout for Larger Microwave Phase Shift
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Solution Overview
Problem
Existing liquid crystal phase shifters face challenges in achieving a sufficient phase shift of microwave signals due to the high inductance and resistance of ITO leads, which result in a small change in capacitance and inadequate phase shifting.
Innovation Solution
The design includes a liquid crystal phase shifter with a second electrode layer positioned in a peripheral region of the substrate, reducing the length of conductive wires and their inductance and resistance, and featuring a microstrip electrode layer with branch structures that receive different voltages to create an electric field and rotate liquid crystal molecules, thereby changing the dielectric constant and achieving a larger phase shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO leads are used to connect electrodes, then the device can be manufactured with standard materials, but the inductance and resistance are high resulting in insufficient phase shift
Solution Approach 1:
The patent extracts the harmful ITO leads from the system and replaces them with a direct ground electrode connection. The ground electrode is positioned in the peripheral region of the substrate, eliminating the need for long ITO leads and thereby removing the source of high inductance and resistance that limited phase shift capability.
Solution Approach 2:
The patent introduces a ground electrode as an intermediary element that provides a low-inductance, low-resistance path to ground. This ground electrode serves as a mediator between the microstrip electrode and the reference potential, replacing the problematic ITO leads and enabling effective phase control.
2Object-affected harmful factors
If the second electrode layer is positioned in the peripheral region, then the inductance and resistance are reduced, but the overlapping area with the microstrip electrode is limited
Solution Approach 1:
The patent positions the ground electrode in the peripheral region of the substrate, utilizing the lateral dimension rather than vertical stacking. This spatial arrangement in the peripheral area provides sufficient overlapping area with the microstrip electrode while maintaining short connection lengths, thus achieving both low inductance/resistance and adequate capacitance.
3Reliability
If branch structures are added to the microstrip electrode, then the electric field distribution is improved, but the device complexity increases
Solution Approach 1:
The microstrip electrode is segmented into a main body structure and multiple branch structures. These branches divide the electric field into multiple regions, improving phase shift uniformity across the liquid crystal layer. The segmentation is achieved through simple geometric extensions rather than complex three-dimensional structures.
Solution Approach 2:
The branch structures are strategically positioned to create localized electric field enhancement in specific regions. Each branch structure provides tailored field distribution in its corresponding area, allowing precise control of phase shift characteristics in different zones of the device.
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 configuration effectively reduces the inductance and resistance of conductive wires, allowing for a significant change in capacitance and achieving a desired phase shift of microwave signals, enhancing the performance of the liquid crystal phase shifter.
Implementation Method 1
applying a second voltage different from the first voltage to the second electrode layer to generate an electric field between the first electrode layer and the second electrode layer
Implementation Method 2
such that long axes of liquid crystal molecules of the liquid crystal layer are substantially parallel or substantially perpendicular to a direction of the electric field
Implementation Method 3
an orthographic projection of each first finger on the first base plate at least partially overlaps an orthographic projection of a corresponding branch structure on the first base plate
Implementation Method 4
reducing the length of conductive wires and their inductance and resistance
Data Source
AI summary
There is provided a liquid crystal phase shifter including first and second substrates opposite to each other, and a liquid crystal layer between the first and second substrates. The first substrate includes a first base plate and a first electrode layer at a side of the first base plate proximal to the liquid crystal layer. The second substrate includes a second base plate and a second electrode layer at a side of the second base plate proximal to the liquid crystal layer. The first electrode layer includes a main body structure having a first side and a second side opposite to each other with respect to an extension direction of the main body structure, and a plurality of branch structures connected to at least one of the first side and the second side of the main body structure. The second electrode layer includes a plurality of first fingers.