Nested Double-Coil Liquid Crystal Phase Shifter Impedance
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Solution Overview
Problem
Existing liquid crystal phase shifters face difficulties in impedance matching due to inductive impedance of microstrips, leading to increased return loss and challenges in optimizing phase shifting performance.
Innovation Solution
A liquid crystal phase shifter design featuring nested double-coil microstrips with opposite coiling directions, where the first and second transmission lines are nested in a direction perpendicular to the substrate plane, reducing inductive impedance and facilitating impedance matching by offsetting magnetic fields, thus optimizing phase shifting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the microstrip is designed in a coil shape to increase its length for achieving complete phase shift, then the phase shifting capability is improved, but the impedance becomes inductive and impedance matching becomes difficult
Solution Approach 1:
The patent employs a nested double-coil structure where the first transmission line and second transmission line are nested within each other in a direction perpendicular to the substrate plane. This nesting arrangement allows both coils to occupy the same spatial footprint while maintaining opposite coiling directions, thereby achieving complete phase shift without excessive inductive impedance
Solution Approach 2:
The patent utilizes asymmetry by designing the first transmission line and second transmission line with opposite coiling directions (one clockwise, one counter-clockwise). This asymmetric configuration causes the magnetic fields generated by the two coils to oppose each other, canceling out the inductive impedance while preserving the phase shifting function
2Length of moving object
If the microstrip is designed in a coil shape to increase its length, then the phase shift capability is improved, but the return loss increases due to impedance mismatch
Solution Approach 1:
The nested double-coil structure enables both transmission lines to be compactly arranged with opposite coiling directions, achieving the required electrical length for complete phase shift while minimizing inductive effects that cause return loss
Solution Approach 2:
By configuring the first and second transmission lines with opposite coiling directions, the magnetic fields cancel each other out, reducing inductive impedance and thereby decreasing return loss while maintaining the necessary phase shift capability
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 nested double-coil structure significantly reduces inductive impedance, making impedance matching easier, decreases return loss, and enhances the phase shifting effect of radio frequency signals, while also reducing the size and weight of the phase shifter.
Implementation Method 1
nested double-coil microstrips with opposite coiling directions, where the first and second transmission lines are nested in a direction perpendicular to the substrate plane, reducing inductive impedance and facilitating impedance matching by offsetting magnetic fields
Implementation Method 2
liquid crystals in a liquid crystal cell rotate under an electric field formed between a microstrip and a ground electrode, and thus a dielectric constant of the liquid crystals may change, thereby shifting the phase of the radio frequency signal
Data Source
AI summary
Provided are a liquid crystal phase shifter, a manufacturing method thereof, and a liquid crystal antenna. The liquid crystal phase shifter includes a first substrate, a second substrate, microstrips, a ground electrode, and liquid crystals located between the at least one microstrip and the ground electrode. The microstrip line is disposed on a side of the second substrate facing towards the first substrate and includes a first transmission line and a second transmission line that are each a coil and are nested with each other in a direction perpendicular to a plane of the second substrate. The coiling transmission directions of radio frequency signals transmitted on the first and second transmission lines are opposite. The ground electrode overlaps both the first transmission line and the second transmission line in the direction perpendicular to the plane of the second substrate.