This paper focuses on the exploitation of linear-frequency-modulated continuous-wave (LFMCW) radars for noncontact range tracking vital signs, e.g., respiration. Such short-range system combines hardware simplicity and precision, thus outperforming other remote-sensing approaches in addressed biomedical scenario. A rigorous mathematical analysis operating principle LFMCW radar context vital-sign monitoring, which includes explanation key aspects maintenance coherence, is detailed. precise...

This paper presents a portable radar system for short-range localization, inverse synthetic aperture imaging, and vital sign tracking. The proposed sensor incorporates frequency-modulated continuous-wave (FMCW) interferometry (Doppler) modes, which enable this to obtain both absolute range information tiny signs (i.e., respiration heartbeat) of human targets. These two different operation modes can be switched through an on-board microcontroller. To simplify the system, utilizes audio card...

A new combline filter structure with a continuous tunability for both the center frequency and bandwidth is presented in this paper. The passband-width achieved by placing variable coupling reducers between resonators. reducers, operating as control subnetworks, are designed detuned resonators made up of line segment ending capacitor. proposed experimentally validated design, construction suspended stripline technology, characterization low-cost prototype terrestrial digital video...

A new class of sharp-rejection, low insertion-loss wide-band planar filters is presented in this letter. The proposed filter topology uses transversal signal-interference filtering sections made up two transmission-line segments connected parallel. Thus, under signal-interaction principles, the action comes about through generation multiple out-of-band power transmission zeros and constructive in-passband signal combinations. Design equations guidelines to adjust both bandwidth performance...

A class of frequency-reconfigurable input-reflectionless/absorptive RF/microwave filters is presented. They consist tunable complementary-duplexer architectures that are composed a main and an auxiliary channel with opposite filtering transfer functions. By loading the reference-impedance resistor by taking output node as terminal overall circuit, network same type theoretically perfect input-reflectionless behavior at all frequencies can be realized. This technique applied to design...

This paper addresses the exploitation of signal-interference concepts for realization single/multi-frequency Wilkinson-type filtering power dividers in planar/lumped-element technologies. By embedding transversal sections into arms conventional power-divider topologies, RF/microwave power-distribution actions with intrinsic mono/multi-band bandpass capabilities can be obtained. Analytical equations and rules theoretical synthesis this dual-function device are derived. The generalization...

An original and simple approach to the design of fully reconfigurable multi-band microwave bandpass filters (BPFs) with an arbitrary number passbands is reported in this paper. It exploits use innovative quasi-BPF configuration made up different sets controllable mono-frequency resonators separately shape each tunable passband. Thus, high-selectivity filtering transfer functions exhibiting independent control terms center frequency, bandwidth, transmission zeros can be synthesized....

Microwave planar balanced single-/dual-band bandpass filters (BPFs) with symmetrical quasi-reflectionless differential-mode behavior are presented in this letter. They made up of a direct BPF branch virtually short-ended stubs operation, whose input and output accesses loaded stub-loaded-type bandstop filter (BSF) branches that terminated resistor. These BSF exhibit quasi-complementary transfer function regard to the one absorb input-signal energy not transmitted by achieve capabilities. The...

A coupling-matrix approach for the theoretical design of a type input-reflectionless RF/microwave bandpass filters (BPFs) and bandstop (BSFs) is presented. They are based on diplexer architectures with arbitrary-order filtering channels that feature complementary transfer functions. The transmission behavior these reflectionless defined by channel not loaded at its output, whereas input-signal energy transmitted this branch completely dissipated loading resistor other channel. Analytical...

A type of compact single/multi-band coupled-multiline filtering section and its application to the design RF devices are presented. This one-port cell is made up N + 1 intercoupled quarter-wavelength transmission-line segments for generation a transfer function with total transmission zeros (TZs) distributed at both sides all first-order passbands when arranged in mode. Design formulas produced poles TZs corresponding normalized coupling-routing diagram illustrative theoretical responses...

A new type of RF microwave differential-mode planar multiband bandpass filters (BPFs) are presented. Each symmetrical half the proposed balanced filtering architecture is composed in-series cascade K N-stub-loaded cells through K-1 inter-connection transmission-line segments to synthesize a transfer function with N th-order passbands. Additional features this BPF topology as follows: 1) generation transmission zeros at both sides all passbands; 2) high common-mode power-rejection levels...

A type of symmetrical RF bandpass filters (BPFs) with quasi-absorptive functionality are presented. They composed a section that is loaded at its input/output ports nearly complementary resistively terminated bandstop sections. In this manner, the input-signal energy not transmitted by dissipated loading resistors sections to attain quasi-reflectionless behavior. The theoretical analysis first-order BPF stage detailed. addition, synthesis examples higher attenuation and sharper rejection...

A new class of Wilkinson-type power dividers with co-integrated bandpass-filter (BPF) functionality and input-reflectionless behavior is presented. They make use a resistively terminated bandstop-filter (BSF) branch that connected at their input terminal exhibits quasi-complementary transfer function regard to the ones BPF-type power-divider arms. Thus, RF-input-signal energy not transmitted by this triple-function reflectionless filtering divider (FPD) its output ports dissipated loading...

A class of stepped-impedance resonator (SIR) dual-band bandpass filter (BPF) with selectivity-enhancement cells is reported. These filtering cells, which are composed two open-ended transmission-line segments interconnected at the input, added one node input and output coupled-line stages. Thus, regard to SIR BPF without they increase order each passband by simultaneously generate transmission zeros (TZs) both sides bands. The operating principles proposed detailed coupling-routing-diagram...

An approach to design RF all-port-reflectionless quasi-elliptic-type single-/dual-band bandpass filters (BPFs) and diplexers with frequency-adaptive constant-absolute-bandwidth (ABW) response is reported. The tunable reflectionless BPF case first addressed, where a balanced-circuit scheme composed of two identical wideband 3-dB quadrature couplers equal reflective-type units synchronous center-frequency agility exploited. input signal split into the amplitude 90° phase shift by coupler then...

An RF input-quasi-reflectionless bandpass filter (BPF) with reconfigurable center frequency and constant absolute bandwidth (ABW) is presented. The proposed BPF based on a tunable complementary-diplexer architecture, which made up of main bandpass-type channel an auxiliary nearly-complementary bandstop-type filtering response that are synchronously reconfigured in frequency. terminated by resistor to absorb the power reflected within its out-of-band region. In this manner, capability...

An approach for the realization of radiofrequency (RF)/microwave balanced filters with simultaneous differential-mode (DM) and common-mode (CM) two-port-reflectionless behavior bandpass, quasi-bandstop, dual-passband applications is reported. These RF filtering components exploit as basic constituent circuit block a type two-layer broadband magic-T, in which its two-side/coplanar arms are designed feeding ports at top layer. Specifically, two replicas this wideband magic-T on...

A new type of microwave dual-passband planar filter exploiting signal-interference techniques is presented. The described approach consists transversal filtering sections shaped by two transmission lines connected in parallel. This section, operating under feedforward signal-combination principles, allows dual-band bandpass responses with several zeros to be synthesized. set analytical formulas and guidelines for the design section are provided. Moreover, its practical usefulness verified...

A new class of bandpass filters with quasi-elliptic frequency response, small physical size, and effective quality factors (Qs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ) the order 1000 are presented. They based on novel hybrid acoustic-wave-lumped-element resonator (AWLR) modules that enable realization fractional bandwidths (FBWs) much larger (0.91-5.1 k xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> <sup...

Split-type multiband bandpass filters (BPFs) and bandstop (BSFs) with input-reflectionless capabilities are reported in this letter. In the BPF case, they consist of a duplexing network split-type channel—main channel—and its complementary resistively terminated BSF channel—auxiliary channel—that absorbs input-signal energy that is not transmitted by overall filter. The counterpart obtained from latter interchanging roles main auxiliary channels. operational foundations, theoretical design...

A new class of adaptive Wilkinson-type filtering power divider that simultaneously exhibits single/multi-band operation, frequency tuning, and controllable number passbands is reported. It exploits the incorporation quasi-bandpass sections into input/output terminals divider, whose quarter-wavelength-long transmission-line segments are reused as impedance inverters between stages. In this manner, bandpass-type transfer functions realized at output nodes along with power-distribution...

Falls are among the leading causes of fatal and non-fatal injuries for seniors. For long-term non-contact detection falls in home nursing environments, a coherent frequency-modulated continuous-wave (FMCW) radar sensor is designed tested. The coherence property developed FMCW helps to preserve phase history signal detected from human subjects, can thus obtain Doppler information based on inverse synthetic aperture (ISAR) imaging. By analyzing changes cross-section (RCS), range, ISAR images...

Hand gesture recognition is an emerging application of portable radar sensors. Most existing works rely on Doppler-radar sensors for non-contact detection hand motions. However, Doppler-radar-based utilizes only the Doppler effect to extract motion features, which imposes a stringent requirement that one in field view sensor, leading limitations practical applications. In this paper, we investigate feasibility using FMCW sensor with range-Doppler processing recognize human gestures when...

This paper provides a comprehensive overview of the recent advances in field wireless contactless sensing circuits and systems for healthcare biomedical applications. In particular, special emphasis is made on implantable devices, radar-based techniques to detect human motions, such as vital signs or gestures, neural interfacing prosthesis, characterization biological materials by means imaging approaches well determination their electrical properties. It believed that this can serve...