Application of Split Ring Resonator (SRR) Loaded Transmission Lines to the Design of Angular Displacement and Velocity Sensors for Space Applications

Abstract

The accurate measurement of the angular displacement and velocity of reaction wheels is necessary for attitude (orientation) control in space vehicles (satellites). In this paper, microwave, contactless and low cost (as compared to optical encoders) sensors useful for that purpose are analyzed in detail. The sensor consists of a rotor and a stator. The rotor is a disk (or a circular crown) of dielectric material, where one or several arrays of equidistant single-loop split ring resonators (SRRs) are etched along its edge, forming circular chains of hundreds of SRRs. The stator is a coplanar waveguide (CPW) also loaded with pairs of single-loop SRRs (etched in the back substrate side), with the centers located in the slot region. The sensing principle is based on the amplitude modulation of a harmonic (single tone continuous wave) feeding signal, achieved when the chains of the rotor are displaced over the SRR pairs of the stator. Both sensor elements (rotor and stator) must be parallel oriented, with the SRR pairs of the CPW in close proximity to the SRR chains of the rotor (and rotated 180 o), in order to favor their coupling. By this means, the transmission coefficient of the CPW is varied by the circular motion of the rotor, and significant amplitude modulation of the feeding signal is achieved. From the envelope function, the angular velocity can be accurately determined. With the proposed sensors, instantaneous and practically unlimited rotation speeds can be measured.

High data density and capacity in chipless radiofrequency identification (chipless-RFID) tags based on double-chains of S-shaped split ring resonators (S-SRRs)

“…In [50,51], a S-SRR identical to those of the tag was etched in the back substrate side of the CPW, a 50 V line. The purpose of this resonant element etched in the reader side is to prevent from the appearance of inter-resonator coupling in the tag chain (through magnetoinductive waves [55][56][57][58][59][60]) as well as multiple couplings between the line and the S-SRRs of the chain [30]. The key aspect is that when one of the S-SRRs of the tag chain is perfectly aligned with the S-SRR of the reader, both particles can be viewed as a single particle, the broadside coupled S-SRR (BC-S-SRR), with smaller fundamental resonance.…”

“…Transmission lines loaded with split ring resonators (SRRs) and with other electrically small resonators [1][2][3][4][5] have been used in numerous microwave applications, including filters [6,7], enhanced bandwidth components [8], multiband components [9][10][11][12], microwave sensors [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] and chipless radiofrequency identification (chipless-RFID) tags [31,32], among others. Concerning chipless RFID tags, the interest in this work, transmission lines loaded with multiple resonant elements, each tuned to a different frequency, have been proposed as multi-resonant frequency domain based tags [31][32][33][34][35][36][37][38][39][40][41][42][43][44].…”

Chipless Radio Frequency Identification (RFID) Sensor for Angular Rotation Monitoring

“…A preliminary study on the possible use of a cross polarization scattering (CPS) system has been presented in Reference [34,35], using chipless RFID tags to design angular rotation sensors, where different resonator geometries (loop, SRR, stubbed loop and dipole) were investigated. A coplanar waveguide loaded with SRRs has been proposed in Reference [36] for measuring angular displacement and velocity. More specifically, two circular chains of rectangular SRRs are etched in the layer applied to the rotor, whereas a CPW transmission line loaded with two pairs of SRRs is placed on the stator, (with a small airgap in between the two layers).…”

Near-Field Chipless-RFID System With High Data Capacity for Security and Authentication Applications

“…Equivalently, the ID code, obtained from the envelope function in time domain, is given by the presence or absence of notches at predefined times. Conceptually, the working principle for tag reading in these chipless RFID tags is similar to the one of the angular velocity sensors reported in [42], [43].…”

“…With this strategy, the dynamic range, or modulation index, is enhanced, as compared to [41]. We report 40-bit chipless RFID tags, which are circularly shaped for proper reading through a step motor used previously by the authors for angular velocity measurements [42], [43].…”