Mixer-Based Isolator for Non-Reciprocal Wave Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing isolators in radio astronomy face challenges in efficiently transmitting progressive waves while attenuating regressive waves, particularly in devices used for detecting feeble radio waves such as microwaves, with existing designs often leading to reciprocal signal transmission and inefficient isolation.
Innovation Solution
The isolator employs a configuration of first and second frequency mixers connected in series, with a local oscillator, phase delayer, and phase shifter to create a phase difference and delay, using SIS quasiparticle mixers and bias voltage settings to optimize the gain difference between progressive and regressive waves, allowing for efficient unidirectional signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing isolator designs are used, then progressive waves can be transmitted, but regressive waves are not sufficiently attenuated due to reciprocal signal transmission
Solution Approach 1:
The patent applies asymmetry by creating a non-reciprocal system using two frequency mixers with different local oscillator phases (0° and 90°). The first mixer upconverts signals with phase φ, while the second mixer downconverts with phase φ+90°, creating asymmetric phase relationships that allow progressive waves to pass while attenuating regressive waves. This asymmetric phase configuration breaks the reciprocity principle and enables directional signal transmission.
Solution Approach 2:
The patent utilizes parameter changes by varying the phase of local oscillators input to each frequency mixer. The local oscillator phase is changed between 0° for the first mixer and 90° for the second mixer, creating phase differences that enable non-reciprocal operation. This parameter variation in the local oscillator phases is the key mechanism for achieving isolation while maintaining low transmission loss.
2Reliability
If phase settings are optimized for maximum isolation, then regressive wave attenuation improves, but device complexity increases
Solution Approach 1:
The patent segments the isolation function into two separate frequency mixers, each handling a specific phase transformation. The first mixer handles upconversion with one phase setting, while the second mixer handles downconversion with a different phase setting. This segmentation allows each component to be optimized independently for its specific function, reducing overall system complexity while achieving maximum isolation efficiency.
Solution Approach 2:
The patent introduces an intermediary phase delayer between the two frequency mixers that provides the necessary 90° phase shift. This intermediary component simplifies the phase control architecture by using a dedicated phase-shifting element rather than complex phase control circuits in each mixer, thereby reducing overall device complexity while maintaining optimal isolation performance.
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 isolator achieves maximum isolation efficiency by optimizing phase settings, providing a gain advantage for progressive waves over regressive waves, operating as a unidirectional amplifier and enabling broadband operation from DC to local oscillation frequency.
Implementation Method 1
the first frequency mixer and the second frequency mixer are connected in series, and the local oscillator is connected to the first frequency mixer and the second frequency mixer and is configured to input a local signal with the same frequency to the first frequency mixer and the second frequency mixer. A signal targeted for isolation can be input to the first frequency mixer, and a frequency of the signal input to the first frequency mixer is up-converted by the local signal; the signal with the up-converted frequency is input to the second frequency mixer; and then a frequency of the signal with the up-converted frequency is down-converted.
Implementation Method 2
the phase delayer is configured to delay a phase of the signal with the frequency up-converted by the first frequency mixer
Implementation Method 3
the phase shifter is configured to convert a phase of the local signal to create a phase difference between the first frequency mixer and the second frequency mixer
Data Source
AI summary
In an isolator, frequency mixers are connected to each other in tandem, a local oscillator is connected to both of the frequency mixers and configured to input a local signal with the same frequency to both of the frequency mixers, the frequency of the signal input to one of the frequency mixers is up-converted by the local signal, then input to the other of the frequency mixers and down-converted, a phase delayer is configured to delay the phase of the signal with the frequency up-converted by the frequency mixer, and a phase shifter is configured to convert the phase of the local signal to cause the phase difference between the two frequency mixers.