Symmetrical High-Frequency Phase Shifter with Varactor Diodes
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Solution Overview
Problem
Existing high-frequency phase shifters lack the ability to continuously and electronically control the transmission phase over a wide angular range with low mismatching and adequate reflection loss, which is essential for antenna technology to electronically steer and shape radiation patterns.
Innovation Solution
A high-frequency phase shifter design featuring a symmetrical two-port network with three two-terminal networks, including series and parallel circuits with variable-capacitance diodes, allowing for extensive phase variation while minimizing reflection loss by using identical variable-capacitance diodes and optimizing reactance elements for low-loss performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a four-terminal hybrid circuit with two variable-capacitance diodes is used to achieve large phase variation range, then the phase can be swept over a large angular range, but adequate reflection loss cannot be achieved due to insufficient compensation of influences
Solution Approach 1:
The phase shifter is divided into multiple two-terminal networks (series and parallel) instead of using a single hybrid circuit. Each two-terminal network contains variable-capacitance diodes that can be independently controlled, allowing the total phase shift to be distributed across multiple segments. This segmentation enables better compensation of reflection influences while maintaining large phase variation range.
Solution Approach 2:
Different two-terminal networks are positioned at different locations within the phase shifter structure (series networks at input/output, parallel networks in between). Each network contributes differently to the overall phase shift and reflection characteristics, allowing local optimization of phase control and reflection compensation at specific points in the signal path.
2Device complexity
If switched diodes are used for phase variation, then the structure is simple, but the phase can only be varied in discrete steps rather than continuously
Solution Approach 1:
The phase shifter uses variable-capacitance diodes (varactors) whose capacitance values can be continuously adjusted by control voltages, rather than using switched diodes that only provide discrete states. This dynamic capability allows continuous phase variation while maintaining a relatively simple diode-based structure, bridging the gap between structural simplicity and operational flexibility.
3Reliability
If more variable-capacitance diodes are added to improve reflection loss compensation, then adequate reflection loss can be achieved, but the device complexity increases
Solution Approach 1:
Each variable-capacitance diode in the two-terminal networks serves multiple functions: it contributes to phase shift variation and simultaneously provides reflection compensation. The series and parallel configurations of the two-terminal networks work together to achieve both objectives with a moderate number of diodes, avoiding the need for excessive components.
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 enables continuous, wide-range electronic control of the transmission phase with low mismatching and reflection loss, achieving a phase variation of nearly 200° with a transmission loss of only 0.3 dB, improving antenna technology's ability to steer and shape radiation patterns effectively.
Implementation Method 1
each series circuit (10, 12) consists of an identical fixed inductance 10 in series and an identical series capacitance element 12 whose capacitance value C(k) is varied by the same control voltage U... each parallel circuit (26, 13) consists of an identical fixed inductance 26 in parallel and an identical parallel capacitance element 13 whose capacitance value C(k) is varied by the same control voltage U
Data Source
AI summary
A high-frequency phase shifter for varying the phase between its high-frequency input signal and its output signal by the transmission phase Φ, consisting of a two-port network which is symmetrical in relation to input and output and which with respect to its high-frequency properties consists of three two-terminal networks consisting of low-loss reactances, wherein at least one of the two-terminal networks is arranged in a series circuit as a two-terminal network in series with one of the connecting ports and at least one of the two-terminal networks is arranged in a parallel circuit as a two-terminal network in parallel with the two-port earth, so that a symmetrical T-circuit or a symmetrical π circuit is provided.