International Journal

A channel estimation method for chipless wireless sensors is presented. The method is developed to suppress interference signals in radio frequency backscatter systems. It uses two adjacent frequency bands to estimate and suppress the disturbing signal of a dynamic interferer. Afterwards a correction of the sensor tag's backscatter signal is achieved. The method has been tested in indoor measureme

In this paper, a passive double-balanced mixer in SiGe HBT technology is presented. Owing to lack of suitable passive mixing elements in the technology, the mixing elements are formed by diode-connected HBTs. The mixer uses lumped element Marchand baluns on both the local oscillator (LO) and the radio frequency (RF) port. A break out of the Marchand balun is measured. This demonstrates good phase

New wireless wearable monitoring systems integrated in professional garments require a high degree of reliability and autonomy. Active textile antenna systems may serve as platforms for body-centric sensing, localisation, and wireless communication systems, in the meanwhile being comfortable and invisible to the wearer. We present a new dedicated comprehensive design paradigm and combine this with

Several types of multiplexers based on isolation circuits have been introduced and investigated. Combining method of two filtering circuits (CMTC) is one way to make multiplexers based on isolation circuits. This method fits well for designing contiguous channel triplexers. A triplexer based on CMTC consists of a conventional transmission line (TL) connected to a diplexer and a composite right/lef

Two compact H-band (220?325 GHz) low-noise millimeter-wave monolithic integrated circuit (MMIC) amplifiers have been developed, based on a grounded coplanar waveguide (GCPW) technology utilizing 50 and 35 nm metamorphic high electron mobility transistors (mHEMTs). For low-loss packaging of the circuits, a set of waveguide-to-microstrip transitions has been realized on 50-?m-thick GaAs substrates d

This paper clarifies what we benefit from single-input?multiple-output (SIMO) or multiple-input?multiple-output (MIMO) radar. We have developed an X-band sparse array imaging radar system capable of operating at both SIMO and MIMO modes. The hybrid radar modes are realized without any modification in hardware, but simply by switching the scheme of waveform generation and post-processing. A compari

Combining a theory for reflection-free termination of coaxial lines together with a novel manufacturing method results in 1-mm coaxial matched loads with an excellent absorption behavior over the frequency range from 0 to 110 GHz. Three different electromagnetic (EM) simulation approaches verify the capability of these matched loads to achieve reflection coefficients smaller than ?43  over the ent

A new approach is proposed to extract the slow-time feature of human motion in high-resolution radars. The approach is based on the self-similarity matrix (SSM) of the radar signals. The Mutual Information is used as a measure of similarity. The SSMs of different radar signals (high-resolution range profile, micro-Doppler, and range-Doppler video sequence) are compared, and the angel-invariant pro

In this paper, an approach to differentiate between various dielectric threat objects in security applications is investigated. The scattering information in form of the Sinclair matrix of relevant scenarios is gained from a fully polarimetric, synthetic aperture radar. Both monostatic and multistatic array configurations are examined. A possible polarimetric calibration procedure is presented. Th

We present a heterodyne frequency-modulated continuous-wave (FMCW) radar, applicable in short-range applications. Owing to a modulation of the transmit (TX) signal, the intermediate frequency (IF) signal can be shifted away from zero frequency to reduce the influence of dc-offsets and low-frequency disturbances like, e.g. flicker noise existing in components like mixers, amplifiers and analog-to-d