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.

In this article, we propose three-dimensional antenna systems for determining the position of electromagnetic radiation source at an unknown location. Received signal power at different antennas and position of radiation source are used as training data for Artificial Neural Network (ANN). It is found that, a well-trained ANN is computationally efficient and capable of predicting the unknown location of the source, from the received power pattern. Two multi-antenna systems with geometry in three dimensions, namely the cube and frustum, are considered in this paper. Further, test results of the proposed method for random positions of electromagnetic source, spanning a hemisphere, are presented for the geometries considered.

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, 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.

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.

In this paper, a small ultra-wideband (UWB) antenna with two stop bands by a compact electromagnetic bandgap (EBG) cell loaded with two new open meander slots is presented. With the coupling of the EBG cell to the feedline, the stop bands are formed. The designed EBG cell is a mushroom type that has the advantages of being able to independently control the stop bands, high responsiveness selectivity of stop bands, easy switching, the need for fewer EBG cells, and low impact on the working characteristics of the antenna. To have a better understanding of the proposed EBG mechanism, characteristic mode analysis is used. The size reduction of the suggested antenna is obtained by halving the reference antenna relative to the axis of symmetry. The measurement results for −10 dB adaptation are from 2.73 to 13 GHz with stop bands at 3.51 GHz (12.9%) and 5.34 GHz (14.1%). The radiation behavior of the minimized antenna is similar to that of a reference antenna. Minimized UWB antenna with transmission function and group delay with small variations in the operating frequency range is suitable for small multiple-input and multiple-output (MIMO) and diversity systems.

Specifications of the substrates are among the most important and problematic parameters that still do not have proper models in the design procedures of metasurfaces. In this paper, a new fast and exact algorithm based on artificial neural networks (ANNs) is presented, which makes it possible to design frequency-selective surfaces (FSSs) on various kinds of standard substrates. Also for the first time, designing FSSs on uniaxial anisotropic substrates can be easily done in short time and without any optimization algorithms. During this paper, first equivalent geometry approach (EGA) is demonstrated as a new method of preparation the ANNs. Then EGA is used to train geometry transformation ANNs. The advantage of this approach is to reduce the size of training datasets by about 98% and prevent from superfluous simulations. Hence, the time needed for training of the networks is much less than before. Numerical results are used to show that the required time for developing FSSs is <200 ms on average, and errors are <2%. For the final validation, a prototype sample of FSS is fabricated on the RO4003 substrate with 20 mil thickness. Both analytical and experimental results confirm the correctness of the predicted values.

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.

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.

We present the results obtained on a multi-mode multi-band 20 W Monolithic Microwave Integrated Circuit (MMIC) power amplifier. The proposed two-stage circuit is based on the silicon Laterally Diffused Metal Oxide Semiconductor (LDMOS) technology. Thanks to dedicated design techniques, it can cover the Digital Cellular Service (DCS), Personal Communications Service (PCS), and UMTS bands (ranging from 1.805 to 2.17 GHz) and deliver more than 20 W of output power, 30 dB of gain and 50% of power added efficiency. When combined in a Doherty configuration with an incremental 40 W MMIC in a dual-path package, the resulted asymmetric MMIC (an industry first) can deliver an unprecedented LDMOS MMIC efficiency of up to 44% at 8 dB back-off in the UMTS band. Then, the DPA has been optimized in conjunction with a novel RF pre-distortion technique, leading to 33–80% energy saving at the system level.

In urban target localization, the presence of walls creates virtual radars (VRs), which can be exploited to aid in localization process. The fact that multipath changes with the radar locations, which are referred to as aspect dependence property, enable us to find a radar location, which reduces wall uncertainties. This paper proposes single-antenna target localization in an enclosed structure taking advantage of VRs. Using ultra-wideband signals, we can resolve the target returns and estimate the correct location by solving monostatic loci at real and VR locations. Simulation results show that the method can precisely and accurately localize the target for a wide range of timing errors.

A new quad-band bandpass filter for Global System for Mobile Communications, Wireless Local Area Network, and Worldwide Interoperability for Microwave Access is designed and fabricated using the stub-loaded resonator (SLR) technology without complex fabrication process, such as via-hole or multi-layer substrate. Owing to the embedded SLR, the proposed quad-mode resonator is compact. Equivalent circuits of the proposed quad-mode resonator are analyzed in detail, and high design freedom is shown because of shifting the passband frequencies individually. Good passband selectivity and isolation of the each passband at 1.8, 2.4, 3.5, and 5.2 GHz can be well achieved due to the transmission zeros appeared near the each passband edges. Experimental results show good agreement with the simulated results.

In this paper, the design of a broadband multi-layer microstrip antenna is presented. The broadband characteristics are the results of coupled resonances of the patch and transmission line through the resonant aperture. For this purpose, a cross-shaped transmission line, a ring slot, and a shaped ring patch are used. The simulation and measurement results indicate that a wide impedance bandwidth of 70% for |S11| < −10 dB and a perfect impedance matching 35% for |S11| < −20 dB are achieved. The gain is stable over the impedance bandwidth. The maximum gain of the proposed antenna is 8.8 dBi at 5 GHz. The radiation pattern, radiation efficiency, and cross-polarization are also suitable throughout the impedance bandwidth.

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.

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.

Two-dimensional scattering of a Gaussian beam by a homogeneous gyrotropic circular cylinder is presented. The incident Gaussian beam source is expanded as an approximate expression with Taylor's series. The transmitted field in the homogeneous gyrotropic cylinder is expressed in terms of the series of wave functions based on the integral equation. The unknown coefficients of the scattered fields are obtained with the aid of the boundary conditions of continuous tangential electric and magnetic fields. Some numerical results are presented and discussed. The result is in agreement with that available as expected when the Gaussian beam degenerates to a plane wave incidence case.

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 a novel compact multi-band printed coplanar waveguide (CPW)-feed antenna for wireless local area network (WLAN)/WiMAX/RFID applications is proposed. The proposed antenna is composed of a multi-triangular structure as metal ground plane and the radiation element with four different branches, both of the structures are printed on the same side of a substrate and the antenna is fed by a CPW. By carefully tuning the locations and the sizes of these four branches, the antenna can yield three different resonating frequencies to cover the desired bands for WLAN/WiMAX/RFID applications. The simulated and measured results demonstrate that the proposed antenna has the impedance bandwidth (for return loss less than −10 dB) of 700 MHz (2.2−2.9 GHz), 540 MHz (3.16–3.7 GHz), and 850 MHz (5.05–5.9 GHz), respectively, which can cover the WLAN 2.4/5.8 GHz bands, the WiMAX 2.5/3.5 GHz bands, and the RFID 2.45/5.8 GHz bands.

By introducing an L-shaped metal plate connecting with the spiral monopole antenna, a planar compact ultra-high-frequency (UHF) tag antenna for radiofrequency identification system is proposed. With the overall antenna size of only 13 × 9 × 1.6 mm3, the proposed tag antenna provides the measured impedance bandwidth of 12 MHz to comply with Taiwan UHF operating band (922–928 MHz). The measured peak gain and antenna efficiency are approximately −1.1 dBi and 27% for Taiwan UHF band, respectively. Meanwhile, the measured reading distance can approach 250 m. Good tag sensitivity is obtained across the desired frequency band.

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.