This paper describes the design considerations, integration issues, packaging, and experimental performance of recently developed D-Band dual-channel transceiver with on-chip antennas fabricated in a SiGe-BiCMOS technology. The design comprises a fully integrated transceiver circuit with quasi-monostatic architecture that operates between 114 and 124 GHz. All analog building blocks are controllable via a serial peripheral interface to reduce the number of connections and facilitate the communication between digital processor and analog building blocks. The two electromagnetically coupled patch antennas are placed on the top of the die with 8.6 dBi gain and have a simulated efficiency of 60%. The chip consumes 450 mW and is wire-bonded into an open-lid 5 × 5 mm2 quad-flat no-leads package. Measurement results for the estimation of range, and azimuth angle in single object situation are presented.

In this paper, the design and test of a single-chip RF pulse-width modulator and driver (PWMD) aimed at exciting a high-power class-E GaN high-power stage at 435 MHz is described. For the required buffer size, avoiding potential ringing of the pulses within the buffer structure presents a major challenge in the design process. Therefore, a smaller test chip capable of driving capacitive loads of up to 5 pF was initially designed, fabricated, and tested. An approach based on three-dimensional electromagnetic simulations was used to validate the test results and offers excellent simulation accuracy. Based on the results obtained for test chip an enlarged PWMD chip capable of driving a 40 W high-power stage has been designed and tested on passive loads representing the targeted final stage.

This study presents a simple switched-band impedance transformer using microstrip lines. The proposed circuit is suitable for loads with frequency-dependent complex impedances at two arbitrary operating frequencies. The transformer comprises two cascaded microstrip lines and two detachable shunt stepped-impedance stubs, which are separately connected to the main line via switching diodes such that provide good matching at one of the two operating frequencies and suppress unwanted signal at the other frequencies. The structure contains several user-set parameters such that designers can create a smaller circuit. The circuit parameters, except the user-set ones, are obtained using the derived design formula. The numerical simulations and experimental results agree well such that validate the proposed structure and the design formula.

Phase retrieval algorithm is an effective method to reconstruct the surface distortions for reflector antennas. As the traditional Fourier iterative algorithms usually stagnate at local minima, we previously proposed a global phase retrieval algorithm, named CMAES-HIO, based on the hybridization of hybrid-input-output algorithm and covariance matrix adaptation evolution strategy. We address the problem of selection of the Zernike order used in the phase parameterization for CMAES-HIO algorithm in this paper. By introducing a hybrid evaluation parameter, which combines the algorithm accuracy and time consumption, we utilize the Monte-Carlo method to simulate the algorithm performance under different random surface distortions. Simulation results show that for an unknown surface distortion, a Zernike order of 5 or 6 is probably the optimum for the comprehensive algorithm performance with respect to time and accuracy.

This research work presents an implantable antenna that operates at 5.8 GHz. By using a radiator with a loop-based design, the antenna can be made smaller. Radiator is made up of three connected rectangular loops. On the substrate’s back side, an I-shaped ground plane is used. As substrate and superstrate, polydimethylsiloxane (PDMS) with dimensions of 7 mm × 5 mm × 0.3 mm is used. The conducting sections are made using copper foil that is 30 µm thick. The suggested antenna is examined by the implantable medical device using realistic human scalp phantom models and a homogenous skin box. Simulated study revealed that it operates around 5.8 GHz with a bandwidth from 5.69 to 5.92 GHz. The specific absorption rate was 0.28 and 0.26 W/kg for skin box and human scalp phantoms, respectively, at 1 mW input power across 1 g volume tissue.

In this paper, the development and designing of angle-independent metamaterial microwave absorbers are presented. The unit cell consists of two concentric circle that are linked by consolidated resistors. The absorber is built on a dielectric substrate (FR4) with a thickness of 3.2 mm (λ/0.07) and a dielectric constant of 4.3. The wideband absorption is acquired in the range of 2.8 to 10.42 GHz with a wide band of 7.62 GHz with absorptivity above 90%. In the area of interest, a flat band is obtained, and to examine the current distribution and electric field in the respective region, two peaks are considered at a frequency of 3.66 and 9.54 GHz, with maximum absorptivity of 99.99% and 99.44%, respectively. The presented absorber is examined under different angles for phi and theta variation. From the phi variation, it is observed that for all the angles, absorptivity does not vary, which confirms that the absorber is acting as an angle independent. The fabricated sheet consists of an array of a unit cell, which is examined inside the anechoic chamber with the help of two horn antennas and vector network analyzer. The tested and simulated results are compared, and it was observed that they are close in their agreement. At the end of the manuscript, the presented and already reported arts are compared, and it is observed that the presented one operates for the low frequency with higher bandwidth. The presented absorber can be practically used for defense applications for Radar Cross Sections reduction.

In this paper, a new methodology to compare the robustness of sensor structures employed in radiofrequency design for test (RF DFT) architectures for RF integrated circuits (ICs) is proposed. First, the yield loss and defect level of the test technique is evaluated using a statistical model of the Circuit under Test (obtained through non-parametric statistics and copula theory). Then, by carrying out the dispersion analysis of the sensor architecture, a figure of merit is established. This methodology reduces the number of iterations in the design flow of RF DFT sensors and makes it possible to evaluate process dispersion. The case study is a SiGe:C BiCMOS LNA tested by a single-probe measurement.

The novel compact size orthogonally fed 2 x 2 Multiple Input and Multiple Output (MIMO) array antenna for mid-band Fifth Generation (5G) wireless application is presented. The antenna configuration consists of diamond-shaped patches employed at the top of substrate. The V-shaped common ground slot structure is employed at the bottom of substrate. A broadband circular polarization is achieved by simply combining two circular polarization modes obtained from ground V slot and top patch feed structure. Mainly, the impedance bandwidth (IBW) and gain are enhanced by protruding slots on ground and cutting edges of patches. The measured result shows that 1.70 – 8.00 GHz (6.30 GHz) of IBW, 8.8 dBic of peak gain, and 3 dB axial ratio bandwidth from 1.81 – 3.87 GHz (2.06 GHz) are obtained. The proposed antenna performances are experimentally validated by fabricating and testing it for measured result analysis without using power divider.

A circularly polarized (CP) broadband antenna is proposed for wireless applications in the range of 2–3 GHz frequency. It consists of asymmetrical Koch fractal boundary patch over a reactive impedance surface (RIS) substrate. The simulations of single-layer Koch fractal antenna, dual layer with square and fractal RIS elements are carried out in a systematic way for broadband CP radiation and corresponding results are presented. For better CP characteristics, properties of fractal curves and dimensions of RIS elements are optimized. The antenna with fractal RIS iteration order one (iteration1) is experimentally studied. The 10-dB return loss bandwidth is 50.35%, whereas 3-dB axial ratio bandwidth is 7.45%, which indicate that by applying fractals concept to RIS technique, with a single probe feed, broadband CP radiation can be obtained.

In this paper, we present the results of using a frequency-stepped continuous-wave radar system to estimate the position of overlapping and electrically good conductive plates. We especially focus on polarimetric scattering effects caused by the step of a lap joint, which is a common welding-geometry. To model the step's contribution to the overall scattered signal, we use a two-dimensional combined field integral equation (CFIE) approach. For demonstrating its practical applicability, the implemented scattering model is verified by measurements. To emphasize the improvements of position estimation by using a CFIE approach, the outcomes of the model are compared to a commonly used point scattering model. Finally, the numerical signal is utilized to precisely estimate the position of the lap joint.

In this paper, we investigate the scattering properties of an array of finite-length single-walled carbon nanotubes (SWCNTs), up to terahertz frequencies. The problem is cast in terms of a Pocklington-like equation. The current density along the CNT is described by a quasi-classical transport model, recently proposed. The numerical solution is obtained by means of the Galerkin method. Case studies are carried out, either referred to isolated SWCNTs and an array of SWCNTs, aimed at investigating the frequency behavior of the scattered field.

An 8 × 8 butler Vivaldi beam-steering antenna array is introduced for X-band application. Circularly polarized array is made of eight Vivaldi elements with 1×8 platform and an 8×8 beam feeding network. Vivaldi radiating element is used in array form to enhance impedance bandwidth and overall efficiency such as gain. Using microwave passive components, for instance, 3 dB branch line couplers and crossover help to have orthogonal modes for feeding each of the elements, hence circular polarization property is achieved. Extracted results show that the array has an impedance bandwidth over 7–12.7 GHz (~58%) for VSWR≤2 and an axial-ratio bandwidth of 3.15 GHz that is between 8.15 and 11.3 GHz (~33%). The peak gain of antenna array is 18 dBi at 10 GHz. The proposed beam-steering antenna with compact size and good operation is capable to cover an angle range from −42 to 55 degree in whole operation frequency.

This paper proposes planar antennas with quadri-polarization diversity using a pair of orthogonal linear polarizations and a pair of orthogonal circular polarizations (CP). A novel feeding network with four input ports and four output ports is presented, allowing antenna polarization diversity by selecting different input ports, which can generate right-handed CP, left-handed CP, horizontal linear polarization, and vertical linear polarization. The first design uses two square patch resonators to synthesize the four polarizations; the second design comprises four circularly polarized patches to synthesize the four polarizations with an improved axial-ratio (the ratio of orthogonal components of an E-field) bandwidth. The proposed designs do not require for embedding PIN diodes and DC-biasing circuits, making them suitable for use in higher-frequency applications where using lump elements would be difficult. The novel antennas provide potential polarization diversity features which can be used for many applications. Details of the antenna design are shown, and the measurement and simulation results are also provided to validate the proposed concept.

A new simple compact ultra-wideband (UWB) dielectric resonator antenna is presented. The antenna consists of a modified stepped microstrip-fed monopole printed antenna loaded with a rectangular dielectric resonator, truncated ground plane, and a parasitic strip underneath the dielectric resonator (DR). Using an optimized truncated ground plane and a combination of stepped feed line with DR an ultra-wide impedance bandwidth of 153% for (∣S11∣ ≤ −10 dB), covering the frequency range of (3.7–28 GHz) is achieved. The added parasitic strip can improve the radiation pattern, especially at high frequencies. The proposed antenna covers almost the entire UWB (3.1–10.6 GHz), Ku (12.4–18 GHz), and K (18–26.6 GHz) frequency bands. Also this antenna has an omnidirectional and stable radiation pattern over the whole operating frequency range and a compact size of (15 × 20 × 5.8 mm3) that make it suitable for wideband wireless system applications. This structure is light weight and can be easily fabricated. A prototype is built and measured. The simulated and measured results are in good agreement.

This paper proposes a practical approach for developing a new class of compact slow-wave coplanar waveguide (CPW) series/shunt stubs, which offer 40% reduction in size relative to a conventional design. It demonstrates that the technique using interdigitated capacitive loading can provide size and cost reductions, while also providing performance enhancements such as better return loss. The experimental prototypes presented in this paper demonstrate the validity of the design method and the ability to print interdigitated capacitors inside the center conductor of the series/shunt stubs. The principle of achieving such high-quality circuits is detailed and is also confirmed by theoretical and experimental results, which are in reasonable agreement up to at least 70 GHz. The paper also presents a family of novel topologies of slow wave bandpass filters based on the proposed capacitively loaded CPW series/shunt stubs.

A bottom-feed omni-directional CP (circularly polarized) antenna array is proposed in this letter. The antenna array is composed of four elements (two printed ZPS (zero-phase-shift) line loops and two half-wavelength dipoles). The four elements are fed with the same phase and amplitude. The ZPS line loops provide the horizontal polarization while the dipoles provide the vertical polarization. Therefore, omni-directional circular polarization is formed in the far field. The feeding network consists of a 1–4 T-shaped power divider formed by parallel strip lines. In order to balance the amplitude of the feeding coaxial cable, the structure is used in the bottom to transfer parallel strip line to micro-strip line. Besides, the loops and the dipoles are placed on the different side of the network to guarantee the omni-directional radiation property. The measured impedance bandwidth of the fabricated antenna is 0.13 GHz (2.40–2.53 GHz) and the measured maximum CP gain at 2.45 GHz is 4.8 dBic.

In this paper, a metasurface (MS)-based multi-functional electromagnetic (EM) structure is proposed to realize its two different applications, namely absorption and radiation. The proposed structure is based on periodic arrays of disk-shaped metallic patches and split rings with four embedded lumped resistors. The metallic vias are inserted from top to bottom to connect the disk-shaped patches with a feeding network designed on the bottom layer where two p-i-n switches are embedded in the feeding network to alter the different functions of the proposed structure. For free space incident plan wave, the designed structure works as an absorber when the p-i-n switches are switched OFF. The absorber operates over a frequency band from 6.2 GHz to 8.2 GHz and unchanged over an incident angle from 0° to 30° for both TE and TM polarized incident waves. The same structure also works as a low scattering and high gain radiator when the p-i-n switches are turned ON and radiate within absorbing frequency band, i.e. from 7.5 to 8.0 GHz. The designed structure is fabricated and experimentally verified for EM absorption and radiation applications.

Detailed analysis of the polarization tracking modules for Ku band active phased array antennas is presented. The proposed transmitter (14.0–14.5 GHz) and receiver (12.25–12.75 GHz) modules are based on the low temperature co-fired ceramic (LTCC) technique, containing orthogonal dual channels with different phases controlled by phase shifters. The effect of amplitude and phase inconsistency between two channels on polarization tracking performance is analyzed. The validity of the analysis is verified by the measurements of the manufactured prototypes. The measured patterns of the active phased array antenna are given to illustrate the effects of the modules on polarization agility, which may be used for Ku band satellite antennas on mobile terminals.

In this study, we present a comprehensive dual-band ambient radio-frequency (RF) energy harvesting system, consisting of rectenna and power management circuit, to harvest energy from 2.45 and 5.8 GHz Wi-Fi. The rectenna employs a metamaterial antenna based on a split-ring resonator, which possesses omni-directional radiation pattern at both frequencies and compact size (0.18λ × 0.25λ at 2.45 GHz). The dual-band rectifier yields the highest efficiency of 42% at 2.45 GHz and 1 dBm input power, 30% at 5.8 GHz and − 7 dBm input power. The maximum RF-DC efficiency for each band is 72% at − 5 dBm and 27% at − 2 dBm, respectively. The power management circuit, consisting of a storing capacitor and a boost converter, is integrated to produce a stable, sufficient output voltage. The energy harvesting system, with its comprehensiveness, is suitable for supplying low-power wireless sensor nodes for indoor applications.

Simple internal multiband monopole antenna with low specific absorption rate (SAR) for most wireless communication applications is presented in this paper. The proposed antenna is an unequal arms monopole antenna with a meander stripoin the other substrate side. The antenna has a simple structure and it is sufficiently small in size to be easily fitted on the housing of a mobile phone or a universal serial bus (USB) dongle with size 20 × 50 × 0.8 mm3. The antenna is designed to operate in different bands to cover most of allocated wireless communication bands in the frequency range from 0.9 to 6 GHz. The proposed antenna has an acceptable average gain of about 2.75 dBi and an average efficiency of about 85% while providing a monopole radiation pattern in both horizontal and elevation planes, with average half-power beam width of 65° in the elevation plane. The simulation and the experimental results of the antenna are in agreement. The SAR in the human head is investigated by using CST 2012 Microwave Studio Hugo Voxel Model.