Directional‐coupler‐basedmicrowave sensors for differentialangular‐displacementmeasurement

Abstract

The novel application of microwave directional couplers to develop angular‐displacement microwave sensors is reported. The proposed sensor approach employs as stator a branch‐line‐type coupler arranged in transversal mode by loading its direct and coupled ports with two distinct‐length open‐ended stubs. Thus, by taking the isolated port of the coupler as the stator output node, a bandpass filtering transfer function with transmission zeros (TZs) is created. Then, a rotor made up of an angularly‐moveable open‐ended stub is attached to a curved section of the longest loading stub of the stator through physical contact, so that their interconnection point varies with the angular‐displacement of the rotor. In this manner, the sensor transfer function is altered with the stub rotation through TZ reallocation, angular‐displacement sensing capabilities are achieved. The theoretical operational foundations of the conceived branch‐line‐coupler‐based microwave angular‐displacement sensor, which features single/multi‐band sensing properties in terms of inter‐TZ spacing and stop band attenuation levels, along with design examples and curves are provided. The extrapolation of this sensor principle to other classes of power‐distribution circuits, such as the rat‐race‐type directional coupler, is also demonstrated. Finally, for experimental‐validation purposes, two 920 MHz microstrip prototypes of the conceived branch‐line‐coupler‐based angular‐displacement microwave‐sensor approach are built and measured.

A method to enhance the accuracy of radio frequency power measurements in particle accelerator high‐frequency systems

“…5 In particle accelerator systems, especially those employing superconducting technology, cavities often experience standing wave states, unloaded, or complete reflections due to aging and beam mismatch, resulting in significant reflections. [6][7][8][9][10] In these conditions, directional couplers with insufficient directivity can lead to inaccurate power measurements, posing challenges for cavity physical analysis, monitoring of microwave power sources, and assessing the transmission line system's operational status. Several approaches, such as using a wiggly line, 11 additive lumped capacitances, 12 and inductor-loading methods, 13 have been proposed to improve the directivity of directional couplers.…”

“…However, nonideal directional couplers characterized by poor directivity can introduce measurement errors due to cross‐talk from the reverse signal 5 . In particle accelerator systems, especially those employing superconducting technology, cavities often experience standing wave states, unloaded, or complete reflections due to aging and beam mismatch, resulting in significant reflections 6–10 . In these conditions, directional couplers with insufficient directivity can lead to inaccurate power measurements, posing challenges for cavity physical analysis, monitoring of microwave power sources, and assessing the transmission line system's operational status.…”

AI-Assisted Ultra-High-Sensitivity/Resolution Active-Coupled CSRR-Based Sensor with Embedded Selectivity

“…Enhancing the sensitivity of resonator-based sensors makes them a fitting replacement for traditional, expensive equipment used for detecting minute variations. Some works in the literature for sensitivity enhancement include metamaterial SRR [31], branch line couplers [32], coupledline couplers [33,34], and directional couplers [35]. In this work, conventional CSRRs are coupled together to exploit the sensitive region of the coupled CSRRs (CCSRR).…”

An ultrahigh‐sensitivity microwave angular displacement sensor with a wide dynamic range

“…Recently, various types of microwave sensors have been reported, such as liquid and displacement sensors 4,5 . Among them, microwave angular displacement sensor is used to measure the rotation angle and has attracted much attention due to their low manufacturing and measurement cost 6 . It is usually composed of a stator and a rotor, and the stator is fixed onto the test platform with the rotor rotating 7 .…”

“…4,5 Among them, microwave angular displacement sensor is used to measure the rotation angle and has attracted much attention due to their low manufacturing and measurement cost. 6 It is usually composed of a stator and a rotor, and the stator is fixed onto the test platform with the rotor rotating. 7 In the measurements, the rotation angle can be retrieved by the variations in the sensor responses such as amplitude and resonant frequency.…”