The design of a low-cost, flexible, miniaturized, and a high code density chipless radio-frequency identification (RFID) tag is presented as a solution for tracking the transportation of biomass fuel pellets. The performance of the tag is presented and demonstrates the applicability of the design for different material systems, while maintaining a compact size of 5.06 cm2. The tag consists of nested concentric hexagonal elements and a central spiral resonator suitable for ID encoding. The tag presented demonstrates code density of 3.6-bits/cm2, possesses angular stability up to 60°, and high radar cross section (RCS). The tag performance was also observed for tracking 5 kg of fly-ash biomass. Additionally, as the tag mass mostly consists of FR4, PET, or Taconic TLX-0 with a minute mass of either copper, gold, or silver, the tag can be easily combusted and disposed of during biomass combustion. The novel features of this tag are the combination of hexagonal and spiral shape slots for maximum space utilization thereby achieving high RCS signatures along with high code density. All these properties of the proposed chipless RFID tag provide a pioneering pathway for a real-time biomass tracking application.

Design and fabrication of a microstrip feedline-based Vivaldi antenna in the frequency range of 6.0–8.0 GHz have been presented. The Vivaldi antenna is a planar antenna, fabricated at the microstrip feedline by having an exponentially tapered slot profile on it. An optimized computer-aided design has been developed and simulated for the desired radiation parameters like voltage standing wave ratio, bandwidth, directionality, beam-width, etc. The optimized design has been fabricated and tested. Wherever the results are not found as desired; problem has been comprehensively investigated and analyzed. This is found associated with a discontinuity at feed line, fabrication tolerance constraints and parasitic capacitance at the edges or the bent of the microstrip feedline which introduce the parasitic reactance in antenna design. Here, the presented work explores a generalized theoretical procedure for the compensation of associated problem by incorporating the reactive patch on the feedline. The developed theory is applied in fabrication and tested for the desired results.

This paper analyzes the noise properties of balanced amplifier configurations in terms of noise waves and discusses the effect of various amplifier configurations on the noise and signal parameters. It shows how the noise generated in the load on the input coupler of a balanced amplifier deteriorates the amplifiers noise resistance parameter with respect to that of its component amplifiers. The properties of two new balanced amplifier configurations will be discussed, which enable the reduction or elimination of this deterioration.

In this paper, a high gain broadband low profile microstrip antenna with the dual-layered substrate and four parasitic metal elements is presented. The proposed microstrip antenna is mainly composed of four parts: four circular parasitic metal patches with dual arced breaches, a rectangular metal patch sandwiched between substrates, a square ground plane, and two-square substrates. The circular parasitic elements are the main radiation structure and determine the characteristics of the proposed antenna are closely related to the parasitic elements. The proposed antenna has been fabricated for experimental measurement. The reflection coefficient, radiation pattern, radiation efficiency, and gain have been studied in detail. The simulated and measured impedance bandwidth is 27.0% (3.30–4.33 GHz), the maximum realized peak gain reaches up to 6.52 dBi at the frequency of 3.65 GHz. The radiation pattern has a single peak which is perpendicular to the surface of the substrate. The proposed antenna is suitable to be applied in the 5G mobile or WiMAX wireless communication. Dual antenna with a pair of parasitic elements has been investigated numerically to explain the principle of the proposed antenna.

A microwave rectifier at 5.8 GHz without any capacitors is presented, which owns a measured MW-to-DC conversion efficiency of 68.1%. A harmonic rejection filter and a DC pass filter, which replace lumped capacitors in conventional microwave rectifiers, are applied to suppressing the harmonics produced by an HSMS-286 Schottky diode during rectifying. At the fundamental frequency, a microstrip impedance transformer which contains a shunt λg/8 short-ended microstrip transmission line and two short series microstrip transmission lines are applied to compensating the imaginary impedance of the diode and matching the input impedance of the rectifier. The measured MW-to-DC conversion efficiency agrees well to the simulated results. The novel rectifier without any lumped passive elements may be applied for power transmission system at higher microwave frequencies.

This paper presents a review of the recent advances in the field of substrate integrated waveguide (SIW) filters, with particular emphasis on the techniques adopted to increase the out-of-band rejection of the filters and on the miniaturization strategies. After an overview of classical approaches to introduce transmission zeros in SIW filters, a number of recently introduced techniques are presented. In particular, the use of specially implemented extracted-poles topologies and of pre-filters is described, discussed, and compared. For each of these techniques, numerical and experimental results are reported for validation.

This paper synthesizes protocol measurements for Ultra High Frequency (UHF) radiofrequency identification (RFID) tags’ performance. We introduce the main parameters allowing the evaluation of an inlay tag performances. We characterize all devices implemented on the test bench. We explain the different programs and all methods used for the software automation. Finally, we studied the variation of the measured parameters as a function of power, frequency, or tag orientation, both in free space and in disturbed environment through our automated test bench

The design of integrated systems requires the knowledge of the values of the effective permittivity of the substrate. Designing antenna using computer-aided design tools is a long process that necessitates doing iterative steps to find the correct dimensions that meet specific requirements at a certain operating frequency. The objective of this work is to propose an analytic model to reduce the time required for the design. By using electromagnetic simulation, the effect of the relative permittivity and the height of the substrate on the final effective permittivity have been studied. An analytic model that helps the designer in estimating the value of the effective permittivity has been proposed.

In this paper, the design of a miniature antenna dedicated to the detection of airliners through the demodulation of Automatic Dependence Surveillance-Broadcast system (ADS-B) signals is presented. This antenna is designed for being embedded on the top of a drone in order to detect and avoid collisions with airliners. This antenna consists of an array of Planar Inverted-F Antennas, a quadrature feed network (FN) and a reflector plane (RP). The FN is designed to have output signals with the same amplitude and a 90° phase difference between each other. It achieves circular polarization and maintains the axial ratio of the antenna under −3 dB at the desired frequency (1.09 GHz). The antenna with the FN was manufactured and characterized. It weighs approximately 145 kg with its RP. The measured gain of the proposed antenna is about +3.7 dBi. To validate the design, the manufactured antenna was tested with a Universal Software Radio Peripheral for the processing of ADS-B signals at the French National Microwaves Days 2019 (JNM) student contest. The detection of airliners can reach up to 437 km.

In this paper, a novel wideband right-angle transition between thin substrate integrated waveguide (SIW) and rectangular waveguide (RWG) based on multi-section structure operating at center frequency 31.5 GHz is presented. A multi-section SIW with a rectangular aperture etched on the broad wall and two stepped ridges embedded in the RWG flange are introduced to obtain a wide impedance matching. The simulations show that the bandwidth with return loss better than 20 dB is about 17 GHz. In order to verify our designs, two back-to-back transitions with different lengths are fabricated and measured. The experimental results agree well with simulations. The proposed component shows an insertion loss less than 0.44 dB and a return loss better than 14.5 dB over 12.15 GH, which corresponds to 38.57% bandwidth.

In this paper, we present a 28 GHz antenna array in package which covers the n257 and n258 frequency bands designated for 5G applications. The dipole antenna array is placed on one of the two re-distribution layers in the fan-out eWLB (embedded Wafer Level Ball Grid Array) package. For TX and RX, separate but identical antenna arrays are placed on each side of the die. The paper presents a novel horn-shaped heatsink which not only dissipates the heat, but also improves the radiation performance. The four-elements dipole array has the impedance bandwidth of almost 6 GHz (24–30 GHz) and shows a maximum realized gain of 9.5 dBi. Beam-steering in ± 35 deg is achieved in the azimuth plane (H-plane) by providing different phases to the dipoles through the chip. The measurements nicely agree with the simulation results.

This paper aims to present some outcomes from a European Space Agency (ESA) Technology Research Programme (TRP) project on R&D of new design techniques, concepts, and filtering configurations for tunable IF (intermediate frequency) filters with a compact footprint, wide bandwidth tuning range (covering from 49 to 478 MHz at f0 = 1 GHz) as well as equivalent high-Q performance (i.e. low insertion loss variation and high selectivity by using low-Q resonators). In order to obtain a wide tuning range, the proposed filtering configuration utilizes a new tuning technique that only necessitates control of coupling values with simple DC control circuits, without the need of tuning the electrical length of resonators to avoid deviating the center frequency. Furthermore, in order to achieve the equivalent high-Q performance, a novel lossy technique by using a centrally resistor-loaded half-wavelength resonator is adopted. For the proof of concept, a six-pole prototype filter is designed, fabricated, and tested.

This paper proposes fractal-inspired array antennae for wideband applications. The proposed antennae have a resonance frequency range of 20–40 GHz. The modified fractal antennae are fabricated with a height of 1.6 mm, substrate width, and length of 100, 50, 25, and 18.75 mm2, and a simulated result shows that the gain is increased to 11.04, 11.9, 8.4, and 6 dBi, and the designed antennae radiate power with directivity of 11.3, 13.4, 9.29, and 7.17 dBi concerning proposed designs A, B, C, and D, respectively. The proposed antennae with 5G New Radio (NR) bands have more radiation concerning resonate frequencies in the 20–40 GHz range with Φ = 0°, Φ = 90°, and θ = 90°. Moreover, the bandwidths for applications covered in the 5G NR and sub-6G are 1.92, 0.73, 0.7, 2.4, 1.3, 5.3, and 1.26 GHz, and 3.4, 3.7, 2.67, and 4.65 GHz, and 2, 3.5, and 1.57 GHz, and 2.5, 1.5, and 1.0 GHz with the maximum return loss of 37 dB, 32.8 dB, 31.2 dB, and 23 dB with corresponding resonate frequencies as 21.5, 27.6, 33, and 27.6 GHz concerning designs A, B, C, and D, respectively. The proposed antennae have been implemented and validated using Computer Simulation Technology (CST), Vector Network Analyzer (VNA), spectrum analyzer, and power sensor.

Air target recognition is a critical step in the radar processing chain and reliable features are necessary to make a decision. The number and position of jet engines are useful features to perform a pre-classification and give a list of possible targets. To extract these features, a sparse decomposition framework for inverse synthetic aperture radar (ISAR) images is presented. With this framework different components of the target can be detected, if signal models for these parts are available. To use it for the detection of jet engines, a review of a signal model for air intakes, which was developed by Borden, is given. This model is based on the common assumption that the propagation of electromagnetic waves inside jet engines has the same dispersive behavior as inside waveguides. With this model a decomposition of a real ISAR image, measured with the tracking and imaging radar system of Fraunhofer FHR, into point-like scattering centers and jet engines is presented.

In this article, a multiband antenna for various wireless communications is proposed for WWAN, Bluetooth, WiMAX, WLAN, and Downlink satellite system. The antenna consists of a radiating patch and a rectangular ground plane with four L-shaped stubs which are embedded as side arms to obtain a resonating band for WWAN (1.9GHz), Bluetooth (2.4 GHz), WiMAX (2.5, 3.5, and 5.5 GHz), and WLAN (5.5 GHz) wireless systems and a C-shaped stub is etched on the radiating patch to obtain a higher WLAN band (2.4, 5.2, and 5.8 GHz) and a satellite downlink system (7.5 GHz). The proposed antenna exhibits circular polarization at WWAN band and linear polarization for remaining applications. Also, the proposed antenna exhibits an omnidirectional radiation pattern.

This paper introduces a VDD generator for the ultrahigh frequency (UHF) passive Radio-frequency identification (RFID) tag, consisting of an RF-limiter, an NMOS rectifier, a DC-limiter, and a regulator. The proposed NMOS rectifier utilizes diode-connected native NMOS transistors with ultralow-threshold voltage instead of Schottky diodes. The theoretical equations for predicting the performance of the VDD generator are provided and verified by both simulation results in 90 nm CMOS process. The proposed VDD generator generates a 1.19-V stable output voltage with low-power dissipation and a 26.96% larger power conversion efficiency under conditions of 50 Ω antenna, 900 MHz, −23 dBm input power and 1 M DC output load. The chip area of the proposed VDD generator is only 105 × 85 μm. The simulation results indicated that the presented novel VDD generator is capable to provide efficient, stable, and input-independent power supply for Passive UHF RFID tag

Though compact polarimetric approaches have been developed and applied in space and geo researching systems they have not been taken into consideration in automotive applications, yet. A sensor system has been designed to conduct polarimetric measurements in the 77 GHz frequency band, which is permitted for automotive usage. This system is able to transceive linearly as well as circularly polarized electromagnetic continuous waves. Depending on the case of application, the frequency output can be set statically or modulated over time within adjustable parameters. Hence, a variety of compact polarimetric modes can be performed and compared with full polarimetric approaches. Two compact polarimetric modes, dual-circular polarimetric mode, and circular-transmit-linear-receive, will be introduced and applied in this contribution. Their operability in this frequency range will be investigated after the microstrip antennas as well as the beam focusing dielectrical lense are characterized. Finally, results of a realistical measurement set-up will confirm the practicability of compact polarimetric approaches for double bounce recognition.

A dual wideband design of Sierpinski carpet fractal-shaped planar monopole antenna with a coplanar waveguide (CPW) feed is proposed in this letter. Wide impedance bandwidth of 22% at lower resonance from 4.88 to 6.08 GHz and 41.7% at higher one, which ranges from 9.5 to 14.5 GHz, is obtained. Measured realized antenna gain is around 5 dBi at the lower band centered around 5.5 GHz and are around 4.5 dBi at the higher band. A fabricated prototype is developed with good agreement between simulation and measurement.

A radio frequency (RF) 3-bit digital power amplifier (DPA) is described in this paper. It consists of three RF amplifiers connected at their outputs with a transmission line (TL) network. The three amplifiers are designed for different output powers (POUT). The TL network allows them to load-pull one other to achieve eight different amplitude states by alternatively enabling and disabling the amplifiers via their gate bias. A prototype was designed in the National Instruments' Microwave Office (MWO) for 500 MHz with the aid of a genetic algorithm to optimize the TL network for all seven active (on-) states. The optimizer efficiencies goals were based on data derived from load-pull simulation. The POUT goals were based on a 1 Vrms step-size. In simulation, ≥50% efficiency was achieved at all on-states with 29.7 dBm peak POUT. A practical prototype based on the simulation achieved an efficiency of ≥40% over all seven on-states. A peak POUT of 28.9 dBm was achieved, with the lowest state at 22.4 dBm.

In this work, a very efficient mixed-potential integral-equation formulation is implemented for the rigorous analysis of multilayered structures with arbitrarily shaped two-dimensional periodic metallic and/or dielectric inclusions. Original acceleration techniques have been developed for the computation of the components of the scalar and dyadic Green's functions, based on different types of asymptotic extractions according to the potential considered. The theoretical approach and its computational convenience have been validated through different full-wave analyses concerning both scattering problems and complex-mode dispersive behaviors in various frequency-selective structures for microwave applications.