In this paper, a compact quintuple notched-band ultra-wideband bandpass filter with high selectivity and wide bandwidth is proposed. The filter adopts an approximate closed-loop C-shaped stepped impedance resonator to generate triple notched bands, and uses Hilbert fractal curve slit and L-shaped resonator to create single notched band, respectively. Multiple notched-band are centered at 5.29, 6.61, 7.92, 8.95, and 9.93 GHz to eliminate undesired interference from coexisting wireless services of WLAN, C-band, and X-band. Additionally, two transmission zeros are introduced to enhance the sharp skirt selectivity up to 0.944. This filter could exhibit high sharp selectivity and wider bandwidth simultaneously. The filter is fabricated on a RT/Duroid 5880 substrate (ɛr = 2.2 and thickness = 0.787 mm) and measured to verify the simulation results. Both simulation and measurement are in well agreement, showing the good performance of the filter.

Despite the great progress in data transmission systems using dielectric waveguides (DWGs) in the millimeter-wave (mm-wave) frequency band (30–300 GHz), the signal distortions caused by DWGs have not yet been fully understood. However, such investigations would help to optimize DWGs as a transmission channel in order to further increase data rate and transmission distance of such systems without the need for more complex transceivers. Therefore, this paper presents a detailed study of the expected signal distortions caused by frequency-dependent attenuation and frequency-dependent group delay of circular DWGs at mm-wave frequencies. Based on a low-complexity digital transmission system, the effects of DWGs on the signal-to-noise ratio and the intersymbol interference at the receiver are evaluated. The figures and equations given in this paper allow the reader to easily calculate the channel properties and signal distortions for a wide range of circular DWGs without the need of finite element method solver or other time-consuming numerical simulations. Finally, design recommendations are given to minimize signal distortions for transmitting signals along DWGs.

We present a new ultra-wideband (UWB) band-pass filter (BPF) configuration with a stepped impedance short-circuited stub (SISS)-loaded triple-mode resonator (TMR) and stepped impedance radial stub (SIRS). The novel SISS-loaded TMR and SIRS improve the roll-off ratio at both ends. Even though this UWB BPF is based on a single resonator, the measured results show excellent in-band performance with a small insertion loss less than 0.6 dB and return loss greater than −16 dB. The proposed UWB BPF has sharp roll-off ratio of 96 and 43 dB/GHz, respectively, at the lower and upper edges of the pass-band, and a wide stop-band from 10.8 to 15.6 GHz with the rejection greater than 20 dB.

In this paper, a developed theory of a novel approach of the wave concept iterative process (WCIP) method is presented. This method is well used to demonstrate many attractive properties of metamaterials and to analyze metamaterial-based negative refractive index lenses by easy and speedy computation of the electromagnetic field distribution. These metamaterial-based circuits are established by using periodic L–C and C–L networks. The results of simulation using the proposed method are justified theoretically.

A broadband six-way out-of-phase substrate-integrated waveguide (SIW) power divider was designed, analyzed, and fabricated for low loss and out of phase dividing applications. The SIW technology was used to realize the power divider; where it consists of a central dual-disc probe connected with coaxial outer-conductor impedance matching transformer and six SIW-to-microstrip transitions as output probes. Three of the SIW-to-microstrip transitions are located at the top plane, whereas the other three are at the bottom plane of the power divider to achieve the out-of-phase dividing functioning. These transitions are all the same in size and shape for symmetry reason. Good transmissions from coaxial input port to six-way SIW power divider were also achieved. There is a reasonable agreement between measured and simulated results.

A new approach for designing a single-feed circular microstrip antenna with dual-band/multi-band circularly polarized (CP) radiation are demonstrated and studied experimentally. It is presented that by embedding pairs of asymmetrical ring-shaped arc slots to the boundary of both circular patch and the ground plane the impedance bandwidth of the antenna increases. This can be achieved by making use of both mutual coupling between the resonances of the ring-shaped arc slots and the fundamental resonances of the circular antenna. Also, by extending the ring-shaped arc slots out with narrow slots, the circular microstrip patch antenna can perform dual-band/multi-band CP radiation. Further details of the proposed CP microstrip antenna designs are described, and typical experimental results are presented and discussed.

The recent developments in electronic cards such as the network equipment are characterized by the miniaturization of the board size and the increasing complexity of the layout. Because of these requirements, multi-layered printed circuit boards are commonly used and vias connecting signal lines on different layers, or integrated circuit devices to power and ground planes, are frequently used and often essential. However, a via is not an ideal transmission line. Besides, it creates discontinuities at high frequencies leading to high insertion loss degradation of signal which limits the performances of integrated circuit and systems. In this paper, the impacts of coupling between via and parallel-plates cavity on the response of microwave integrated devices are highlighted in the first part. Then, to describe the intrinsic interaction between the via transition and parallel-plate modes, the notion of parallel-plates matrix impedances is presented and new boundary conditions like open or plated through holes shielded boundaries of the cavities are introduced. Then, using this physics-based model, an intuitive equivalent circuit has been developed. Finally, the proposed approach and the equivalent circuits were validated by using comparisons with electromagnetic simulations and measurements in different scenarios.

In this paper, a novel miniaturized and flexible dual band frequency selective surface (FSS) is presented. This FSS provides effective shielding in X-band and Ku- band, with a frequency response of 9.4 and 16.7 GHz, respectively. The proposed FSS provides 924 MHz bandwidth at X-band and 1.34 GHz bandwidth at Ku-band with an insertion loss of 20 dB. Moreover, the proposed design is polarization-independent and it provides stable frequency response at various angles of incidences for both transverse electric and transverse magnetic modes. More significantly, the proposed FSS analyzed the bandstop response of the selective frequency and also is suitable for conformal applications. A prototype of the proposed FSS is fabricated. The measured results and simulated results are good in agreement.

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. The radar data are processed with the H-α decomposition algorithm. The H-α scattering characteristics of threat objects are analyzed in terms of a weighted averaging. It is shown that an object classification is possible even for threat objects conceiled under thick layers of clothing. Measurement results are presented to illustrate the topic.

Fractals have unique properties such as self-similarity and space-filling. The use of fractal geometry in antenna design provides a good method for achieving the desired miniaturization, multi-band, and wideband properties. In this communication, novel fractal geometry is proposed based on which a multiband antenna is designed. The proposed antenna has fractal patches which are shaped as different iterations of an eight-pointed star. The multiband behavior is in the frequency range from 4.50 to 17.00 GHz. The proposed antenna is designed on a dielectric substrate Roggers RO4003 lossy with a dielectric constant of εr = 3.55. The antenna has applications in commercial and military communication system.

This research paper introduces a ultra-wideband (UWB) multiple input multiple output (MIMO)/diversity antenna with three rejected bands using one compact electromagnetic band gap (EBG) structure. The suggested EBG structure rejects three bands at WiMAX, WLAN, and the X-band within the passband of the UWB antenna. To achieve compactness in the conventional EBG structure, two via and square slots are introduced. This structure contributes to better impedance matching by using tapered feedline and slots in the radiating patch. To improve the isolation among all four compact UWB monopoles, decoupling strips are extended from the ground plane. Furthermore, the |S21| is below 17 dB in between the antenna elements and the envelope correlation coefficient is below 0.5, which are tolerable values within the UWB range. Furthermore, different MIMO/diversity characteristics are also discussed. An FR-4 substrate with dimensions of 38 × 45 × 1.6 mm3 is used for the fabrication of the suggested structure.

This paper describes an automatic-dependent surveillance–broadcast (ADS–B) implementation for air-to-air and ground-based experimental surveillance within a prototype of a fully automated air traffic management (ATM) system, under a trajectory-based-operations paradigm. The system is built using an air-inclusive implementation of system wide information management (SWIM). This work describes the relations between airborne and ground surveillance (SURGND), the prototype surveillance systems, and their algorithms. System's performance is analyzed with simulated and real data. Results show that the proposed ADS–B implementation can fulfill the most demanding surveillance accuracy requirements.

A novel Scarecrow-shaped patch antenna has been presented for broadband applications. The proposed antenna composed of an elliptical shape radiating patch, partial ground plane, and 50 Ω microstrip line which is Boolean added with the radiating patch. To achieve wide impedance bandwidth, an elliptical notch and two rectangular-shaped parasitic slots have incorporated on the ground plane. This antenna has printed on FR-4 substrate (tan(δ) = 0.02, εr = 4.3) with the thickness of 1.6 mm. It is energized by coaxial feed which is connected with a microstrip line through via. The proposed configuration has examined numerically with the help of CST Microwave Studio and experimentally also. The broadband property of this antenna has been achieved by adjusting the dimensions of an elliptical notch. The antenna exhibits the bandwidth of 116.32% from 1.23 to 4.65 GHz for S11 <−10 dB. Current distribution and far-field pattern at resonating frequencies 1.29, 1.77, 2.28, 2.94, and 3.72 GHz have been studied. It has been found that the far-field pattern is distorted at frequency 3.72 GHz due to higher order modes. Effect of parameters on frequency response of the antenna has also been investigated to know the behavior of the antenna.

We studied the viability of the embedded wafer level ball grid array (eWLB) package environment as an antenna platform for 77 GHz automotive radar sensors and the effects of package fabrication tolerances on the antenna performance. The investigation of different antenna concepts in the eWLB package and their characterization methods are addressed. The design procedures for electrically large, differentially fed loop antennas in a multilayer package structure are introduced. Two different planar antennas are developed and measured in an eWLB package showing promising results such as a gain of 9 GHz and an impedance bandwidth of 8 GHz. An acceptable antenna performance is recorded within the tolerance limits. Therefore, the eWLB package is seen as an appropriate platform for mm-wave antennas and as a good candidate for an antenna-in-package (AiP) concept.

In this paper, a wideband two-segmented four-element triangular dielectric resonator antenna (TDRA) with coaxial probe feed has been proposed. The proposed antenna has been analyzed, optimized, and studied through Ansoft HFSS simulation software. The prototype of the proposed antenna has been fabricated and its input characteristics are measured with the help of R&S Vector Network Analyzer. Good agreement has been obtained between simulated and measured results. The proposed design has been compared with two segments TDRA and found wider bandwidth with lower resonant frequency. The proposed antenna provides monopole-like radiation pattern over the entire bandwidth with nearly 33% bandwidth (return loss ≥10 dB) at a resonant frequency 6.9 GHz and 4.93 dBi peak gain. The proposed antenna is suitable for application of C-band microwave frequencies.

In this paper, a compact circularly polarized quadrifilar antenna with planar inverted-F antenna (PIFA) elements is presented. The proposed antenna consists of four PIFA elements and a Wilkinson divider-based feed network fabricated on FR-4 substrate (ɛr = 4.4, loss tangent = 0.02, thickness = 1.6 mm). The total size of the antenna is 120 × 120 × 13.2 mm3. Impedance matching with a reflection coefficient <−15 dB and an axial ratio (AR) <3 dB are achieved over the global ultra-high frequency (UHF) radio frequency identification (RFID) frequency band and beyond. The realized gain ranges from 2.25 to 3.75 dBic within the frequency band of interest from 860 to 960 MHz with a directional radiation pattern. The proposed antenna is compact, low-cost and extremely wideband in terms of matching and AR compared to state-of-the-art UHF RFID reader antennas.

This paper presents a rollable metamaterial screen for high-efficiency wireless power transfer (WPT) system based on magnetic resonance coupling, which operates at 4.5 MHz. The rollable metamaterial screen with a fully expanded area of 750 mm × 750 mm is located in the middle between transmitter and receiver coils and focuses the magnetic field and, by such a way, significantly improves power transfer efficiency (PTE). The metamaterial screen can be rolled up, e.g. onto the ceiling when it is not used, and thus does not require any designated space for the screen saving space. A WPT system with the rollable metamaterial screen is designed, fabricated, and characterized. Improved PTE is qualitatively and quantitatively verified by light bulb experiments and vector network analyzer measurements. The PTE of the WPT system with the metamaterial screen increases from 36 to 58.52% and 10.24 to 31.36% for the distances between the transmitter and receiver coils 100 and 150 cm, respectively. The effects of lateral and angular misalignments on the PTE of the WPT system are also studied. Obtained results show that the rollable metamaterial screen improves the PTE even at the misaligned condition.

This work presents a methodology for designing microwave acoustic filters, based on two-port bulk acoustic wave resonators (also known as stacked crystal filters), with either Butterworth or Chebyshev response. The presented methodology makes it possible to design this type of filter without any optimization work, and, moreover, for its closed-form expressions design can be obtained. As a validation example, we address the design of a pair of filters for UMTS cellular phone handsets. The different simulations carried out show the good agreement between the transmission response of the designed filters and the theoretical response.

An empirical model has been proposed which provides an excellent fit to the drift of pull-in and release voltages of a MEMS capacitive switch due to bulk dielectric charging. This model correctly fits the linear time dependence over short time spans and transitions to a logarithmic dependence over longer time spans. Using this model to fit measured data enables a quick and efficient determination of the rate of dielectric charging, as well as providing a worst-case prediction of when the switch will fail due to dielectric charging. This model has been used to explore the impact of applied voltage, temperature, and duty factor on switch lifetime.

In this work, we analyze the pressure sensing of a thin film molybdenum/aluminumnitride/molybdenum (Mo/AlN/Mo) microwave/RF MEMS filter fabricated by a simple technology. After an experimental characterization in a frequency range between 1 and 36 GHz, we focused on the piezoelectric effect due to the stress properties of the piezoelectric AlN layer by applying forces by means of weights. Variations in the bandpass region of the microwave/RF filter are observed by proving high sensitivity also for low applied weights. We check by a properly designed three-dimensional (3D) finite-element method (FEM) tool the pressure-sensing property of the proposed device. Finally, we analyze the bad gap property of a chip with central defect around 40 GHz.