This paper presents a novel experimental simulation of ramp-time current control with fuzzy bandwidth for wireless power transmission (WPT) systems. A fuzzy logic control algorithm was designed based on the structure of ramp-time current control in active power filters through simulation of ramp-time bandwidth variation to dynamically adjust the loop width of the ramp-time comparator. Ramp-time current control is the most suitable over other current control techniques and is thus selected for the experiment. Implementation of this approach prevents over-limit of switching frequency and enhances dynamic responses, resulting in long lifespan of power switches and smooth output for WPT systems. Finally, the hypothesis and simulation results were verified by analyzing the prototype model and experiment results.

In this paper, a W-band (80 GHz) sub-harmonic mixer (SHM) IC is designed, fabricated and measured in 130-nm SiGe BiCMOS technology. The presented SHM IC makes use of a common emitter common collector transistor pair structure with a bottom-LO-configuration to decrease the LO power requirement and a tail current source to flatten the conversion gain. On-chip Marchand balun is designed for W-band on-wafer measurements. The SHM IC presented in this paper has exhibited a conversion gain of 3.9 dB at 80 GHz RF signal with an LO power of only −7 dBm at 39.5 GHz. The mixer core consumes only 0.68 mA at a supply voltage of 3.3 V.

This paper reports a differential photoreceiver module designed for short reach applications such as access network and data center interconnect. It consists of a monolithically integrated semi-conductor optical amplifier with a PIN photodiode and a linear transimpedance amplifier (TIA) mounted on the same carrier. A matching circuit is placed between the PIN and the TIA in order to increase the cut-off frequency. The module shows a −3 dB bandwidth of 43 GHz, a single-ended conversion gain of 10 000 V/W for an optical input power of −25 dBm and a sensitivity at 40 Gb/s non-return-to-zero operation of −22.5 dBm for a bit error rate of 10−9.

A novel transmission-line model is used for the analysis of planar structures, including wire-medium (WM) slabs with vertically aligned wires. The network formalism allows for an effective determination of the relevant spectral Green's functions, of the modal dispersion equation via transverse resonance, as well as of the far-field radiation pattern produced by simple sources via reciprocity, as opposed to the more cumbersome field-matching approach. Numerical results, validated also against state-of-the-art simulation software, confirm the accuracy and effectiveness of the proposed approach. In particular, modal and radiation features are presented for a class of leaky-wave antennas based on planar WM loaded configurations covered by partially reflecting screens, for which leaky unimodal regimes are achieved by minimizing spurious radiation from the quasi-transverse electromagnetic (TEM) mode.

In this paper, by using composite right and left handed transmission lines and non-radiating CRLH-TLs, a dual-band 3-way series power divider (SPD) is presented. The proposed dual-band divider is designed and fabricated on an inexpensive FR4 substrate of thickness h = 0.79 mm and a relative dielectric constant of εr = 4.4 to work at 0.915 and 2.440 GHz. Also, in order to improve the isolation characteristics of this divider, three isolation resistors are implemented among output ports. Derived formulas are presented in details. The dual-band nature of the designed SPD, good input return loss, as well as equal power split among the three output ports, flexibility of spacing the output ports arbitrarily apart, and easy integration with planar devices make the proposed divider well suited for feeding many dual-band microwave circuits, such as multipliers, mixers, and planar array antennas. In addition, due to its excellent return-loss at the output ports and its high isolation, the proposed divider in this paper can be used as a power combiner.

A multilayer bandpass filter with ultra-wideband passband is presented in this paper. The filter is designed to have a very wide passband with a fractional bandwidth of about 180% at a center frequency of 10.5 GHz. The filter consists of two sections of parallel-coupled lines loaded at the center with short-circuited stub. Each of the coupled line sections and short-circuited stubs is designed to be a quarter-wavelength long at the desired center frequency. As a result, the filter exhibited a selective filtering characteristic equivalent to a five-pole Chebyshev filter with a very low insertion loss. The proposed filter is realized and fabricated using multilayer liquid crystal polymer substrate. The design is successfully realized in theory and verified by full-wave electromagnetic simulation of the full layout and the experiment where excellent agreement is obtained.

High-resolution imaging with an airborne synthetic aperture radar (SAR) calls for precise trajectory measurements that can hardly be achieved with common navigation systems. In this paper, an efficient method called the local-quadratic map-drift autofocus is developed for the estimation of residual (uncompensated) motion errors directly from the received radar data. The map-drift autofocus is applied locally on short time intervals to estimate the cross-track components of the aircraft acceleration. The estimated acceleration is then integrated to evaluate the residual trajectory errors on the whole data frame interval. The method has been successfully tested with an X-band airborne SAR system.

In this paper, a gain-increased method of cavity-backed slot antennas based on excitation of high-order substrate-integrated waveguide cavity resonance has been proposed. To this end, the metallic posts are introduced in a main cavity to excite the cavity's TM220 mode. Then the properties of the modified cavity's TM220 mode are used to feed an array of 2 × 2 slot antenna. Moreover, to acquire insight of modified cavity's field distribution, a comprehensive modal study was performed on the modified cavity to fully understand the effects of the dividing walls on the cavity's field distribution. Also, compared with HFSS, the modal solution that is proposed in this paper provide a considerable time and storage saving. To validate the simulated results, two types of the proposed antenna forming two different polarizations (horizontal and vertical) are analyzed, simulated, and fabricated. The proposed antennas exhibit relatively gain of 8.2 dBi at resonant frequency and high front-to-back ratio. In addition, the gain-enhanced method proposed in the present paper can be extended for using even higher-order cavity resonances, such as TM440, TM660 etc., if higher gain is desirable. The proposed antennas are suitable for using in many wireless communication systems and some radar systems.

A robust and tuneless micromachined waveguide diplexer operating in the frequency range 71–86 GHz is here presented. The diplexer is based on multiple coupled cavities and it is manufactured using micromachining technology on two staked silicon layers. The diplexer consists of two filters combined to a common waveguide port via an E-plane T-junction. The two eight-order band-pass filters are centered at 73.5 and 83.5 GHz. The fractional bandwidths for two bands are 8.8 and 7.8% at higher- and lower-band, respectively. The measured insertion loss is below 0.7 dB for both the filters and the diplexer isolation is better than 55 dB, as required. The proposed technology allows for a very compact device (<20 × 20 × 1.5 mm) and the first prototypes were proved to be very robust to manufacturing tolerances and environmental tests, thus leading to an excellent tuneless manufacturing yield in future production. The diplexer will be employed in next generation terrestrial radio-link communications front-ends.

A high-gain microstrip patch-type WiMAX antenna operating at 3.5 GHz has been designed with a parasitic radiator and a raised ground plane. Antenna design has been carried out through extensive three-dimensional electromagnetic simulations. The patch antenna itself provides a realized gain of about 3.6 dB at 3.5 GHz. When a parasitic radiator is placed on top of the patch antenna, the gain increases from about 3.6 dB to about 7.4 dB. The raised ground plane further enhances the gain by about 1.5 dB. Hence the overall gain improvement is about 5.3 dB without the need of a radio-frequency amplifier.

Phase shifters are indispensable microwave components. In this paper, a dual-frequency, passive, analog, and reciprocal phase shifter is proposed, deploying the phase-delay characteristics of complementary split-ring resonator (CSRR). A transmission line is loaded with a pair of CSRR in the ground plane and the phase variations are compared with an ideal transmission line. The proposed phase shifter operates in the industrial, scientific and medical (ISM) and wireless local area network (WLAN) bands, providing a phase of 180° at 2.4 GHz and 90° at 5.4 GHz for beam steering applications.

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 contribution, we study the design and experimental characterization of a reconfigurable transmitarray in X-band with reduced focal distance. To this end, we consider an illumination with four feed horn antennas in two different configurations. The focal distance and the horn configuration in the focal plane have been optimized with an in-house simulation tool. The effects of source placement errors and excitation unbalances are also studied. The numerical results show a reduction of the focal distance by a factor 1.8 if compared with the single-source case, for a reconfigurable 400-element transmitarray designed in X-band. Moreover, generation of multiple beams is considered and demonstrated numerically for spatial power combining applications. The experimental results obtained in radiation are in good agreement with the numerical predictions. This multiple-source transmitarray exhibits similar radiation performances as the single-source one in terms of gain, bandwidth and beam tilting capabilities, but with about half its volume. This technique seems very attractive for a better integration on various platforms such as vehicles, drones, aircrafts, buildings, etc.

This paper addresses the study of the variation effects of incident plane wave on a multiconductor transmission line (MTL), using a coupling circuit model of MTL line with plane wave based on the method of characteristics (Branin method). This model is valid in the time and frequency domains. It has also an advantage of not presupposing the conditions of the charges applied to its ends, which allows it to be easily inserted in circuit simulators, such as SPICE, SABER, and ESACAP. We confirm the validity of this model by comparing our simulation results under ESACAP with other results, and we discuss the variation effects of the incident plane wave on an MTL line.

This paper describes a concept of stepped impedance resonators (SIR) built from two coaxial structures fitted inside one another. The resonator is built out of a succession of two coaxial sections in cascade, where the ground conductor of the first one is the central core of the next, or vice-versa. An advantageous property of SIR is that they allow a substantial reduction in size, while keeping away the first harmonic and without strongly degrading the quality factor. After describing the theoretical behavior of the resonator, we will then present the specific properties of this approach in second order filter, conceived, and realized in the UHF band. With this example, we will also address flexibility and tunability aspects, which are the other potentially useful properties of the structure. Measurements and simulations are presented and discussed. The architecture resembles a set of two Russian dolls that fit inside one another.

Impedance tuners are key instruments used for load- and source–pull measurements. They are crucial for any active microwave components, circuits, and systems characterization and optimization. This paper reports theoretical, simulated, and experimental results related to the development of a novel programmable impedance tuner offering high-voltage standing wave ratio (VSWR). After presenting the proposed tuner principle, a fabricated prototype operating at microwave frequencies and based on a 3.5 mm coaxial line is introduced with experimental results. Depending on the targeted frequency band, different pairs of slugs, with optimized length and characteristic impedance, can be used to obtain an optimal VSWR. This first prototype allowed us to demonstrate the interest of the proposed impedance synthesis principle and to identify ways forward to further improve its performances and push forward this promising technology.

In this paper, a triple-band 1 × 2 and 1 × 4 microstrip patch antenna array for next-generation wireless and satellite-based applications are presented. The targeted frequency bands are 3.6, 5.2 and 6.7 GHz, respectively. Simple design procedures and optimization techniques are discussed to achieve better antenna performance. The antenna is designed and simulated using Agilent ADS Momentum using FR4 substrate (εr = 4.2 and h = 1.66 mm). The main patch of the antenna is designed for 3.6 GHz operation. A hybrid feed technique is used for antenna arrays with quarter-wave transformer-based network to match the impedance from the feed-point to the antenna to 50 Ω. The antenna is optimized to resonate at triple-bands by using two symmetrical slits. The single-element triple-band antenna is fabricated and characterized, and a comparison between the simulated and measured antenna is presented. The achieved simulated impedance bandwidths/gains for the 1 × 2 array are 1.67%/7.75, 1.06%/7.7, and 1.65%/9.4 dBi and for 1 × 4 array are 1.67%/10.2, 1.45%/8.2, and 1.05%/10 dBi for 3.6, 5.2, and 6.7 GHz bands, respectively, which are very practical. These antenna arrays can also be used for advanced antenna beam-steering systems.

In this paper, an ultra-wideband (UWB) planar monopole antenna with impedance bandwidth from 2.83 to 11.56 GHz and dual band-notched characteristics is presented. The antenna consists of a small rectangular ground plane, a bat-shaped radiating patch, and a 50-Ω microstrip line. The notched bands are realized by introducing two different types of structures. The half-wavelength spiral-slots are etched on the radiating patch to obtain a notched band in 5.15 5.925 GHz for WLAN, HIPERLAN, and DSRC systems. Based on the single band-notched UWB antenna, the second notched band is realized by etching a folded stepped impedance resonator as defected ground structure on the ground plane for WiMAX and C-band communication systems. The notched frequencies can be adjusted by altering the length of resonant cells. Surface current distributions and equivalent circuit are used to illustrate the notched mechanism. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is suitable and a good candidate for UWB applications.

In order to evaluate a communication system, we need to model the propagation channel of the relevant environments pertaining to that communication. In this paper, we propose a Geometry-Based Stochastic Channel Modeling approach to build up propagation channel simulations to assess the performance of vehicle-to-vehicle wireless communications. Our methodology allows the simulation of dynamic scenarios, with an electromagnetic simulator, to emulate typical propagation environments (rural, highway and urban-like propagation channels). Simple metallic plates are used to represent scatterers in the simulated geometric configurations. The common characteristics defining a propagation channel such as delay spread, angle of arrival distribution, and the delay-Doppler spectrum are obtained through adjustment of the number and location of those simple metallic plates.

This paper presents small balanced bandpass filters exhibiting wide differential-mode pass bands and high common-mode suppression. The filters are implemented in microstrip technology and their topology consists of multisection mirrored stepped impedance resonators (SIRs) alternating with mirrored interdigital capacitors. The mirrored SIRs provide the required common-mode transmission zeros to achieve effective rejection of that mode in the region of interest, i.e. the differential-mode pass band. An automated design method for such filters, based on aggressive space mapping, is reported. The method uses the equivalent circuit model of both the mirrored SIRs and the interdigital capacitors, and filter synthesis is based on a quasi-Newton iterative algorithm where parameter extraction is the key aspect. The automated design approach is illustrated through an order-3 filter, where it is demonstrated that the filter topology is generated from the specifications. As compared with previous balanced filters based on mirrored SIRs coupled through admittance inverters, the proposed filters of this work are smaller and the design method is simplified, since bandwidth compensation due to the narrowband functionality of the inverters is avoided.