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.

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.

This work presents the design, fabrication, and test of X-band and 2–18 GHz wideband high-power single pole double throw (SPDT) monolithic microwave integrated circuit (MMIC) switches in microstrip gallium nitride (GaN) technology. Such switches have demonstrated state-of-the-art performances and RF fabrication yields better than 65%. In particular, the X-band switch exhibits 1 dB insertion loss, better than 37 dB isolation, and a power handling capability better than 39 dBm at a 1 dB insertion loss compression point; the wideband switch shows an insertion loss lower than 2.2 dB, better than 25 dB isolation, and an insertion loss compression of 1 dB at an input drive higher than 38.5 dBm in the entire bandwidth.

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.

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.

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.

The growing demand for communication systems requires multi-channel solutions. However, the number of antennas in communication systems is dictated by the number of channels in each system which is limited by the available space on a broadcasting platform and by the limited available resources. We have developed a Multi-Channel Phase Control coupler in the VHF frequency range enabling a reduction in the number of antennas to a third of the original setup. The system is based on a phase shifter in a meander stripline geometry connected to each channel individually. The channels are then phase matched simultaneously to a single antenna through a computer-controlled capacitor bank connected to each phase shifter. The system performance shows a low insertion loss of 0.5 dB and a low return loss of −15 dB for the multi-channel setup.

A novel calibration network for patch antennas is proposed. We introduce magnetically coupled in-situ probes, which excite the fundamental patch mode. In that way, finite array effects and mutual coupling are taken into account, providing the opportunity for accurate online calibration of active antenna terminals. The specific advantages of the approach are demonstrated for linearly polarized patch antennas. Realization aspects of the multilayer antenna are discussed and the effect of some fabrication imperfections are investigated. Measured S-parameters as well as radiation simulation results of a single patch with the integrated probes are presented. Based on simulation of antenna arrays with in-situ probes the calibration accuracy is given in theory.

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.

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.

This research article represents the design of a simple, smaller, and novel frequency reconfigurable patch antenna for 5G communication using PIN diodes. This antenna operates in both mid-5G and high-5G bands. The antenna is intended to operate in eight distinct modes with three PIN diodes in 5G wireless communication covering 27.46–50 GHz of high-5G band (range n257/n258/n260/n261/n262) and frequencies of the 3–6 GHz of mid-5G band (range n77/n78/n79/n46). The antenna has an overall size of 20 mm × 25 mm × 1.6 mm and is placed upon a low-cost FR4 substrate. A higher radiation efficiency from 75% to 98% is achieved in all the different modes. The resonant frequencies are around 3.46, 4.43, 5.83, 31.8, 35.5, and 46 GHz in different modes of operation. Different switching statuses have been carried out in this research work and their performances have also been illustrated in the form of surface current distribution in different resonant frequencies. The simulated and measured results are compared to highlight its proposed design operation.

The plane wave diffraction by a planar junction consisting of a thick metallic sheet and a lossy double-negative metamaterial slab is studied by using the Uniform Asymptotic Physical Optics approach. This approach assumes the radiation integral as a starting point and uses the physical optics surface currents as sources to be integrated. The integral is manipulated by taking advantage of useful approximations and evaluations, and re-formulated in order to apply an asymptotic procedure able to generate a closed-form approximate solution in the framework of the Uniform Geometrical Theory of Diffraction. Accordingly, advantages and drawbacks result from the application of the proposed solution. The jumps of the geometrical optics field are compensated. Implementation and handling of the computer code are facilitated by the evaluation of well-known functions and parameters. No differential/integral equations or special functions must be computed.

A compact and planar broadband circularly polarized (CP) eighth-mode substrate integrated waveguide (EMSIW) antenna is proposed in this paper. An isosceles right triangular waveguide with one electric sidewall (located on one of its catheti) and two magnetic sidewalls (located on the other two edges of the triangle) is presented to investigate the characteristics of the EMSIW. The closed-form mode solutions of the electromagnetic field components and the cut-off frequencies are derived for all propagating modes in this triangular waveguide. The simulated electromagnetic field distribution is consistent with the analytical results. The resonant frequencies of the EMSIW cavity are then determined. A CP antenna consisting of four EMSIW elements is designed, fabricated, and measured. The measured 3-dB axial ratio bandwidth of the antenna is 21.6% from 4.72 to 5.86 GHz. Within this frequency range, the measured reflection coefficient is below −10 dB, and the measured peak gain in circular polarization at broadside is 6.89 dBic at 5.1 GHz.

This paper reports on high-order balanced bandpass filters (BPFs) that are continuously tunable in terms of frequency and bandwidth and can be intrinsically switched-off. They use a hybrid integration scheme based on two different types of capacitively loaded resonators—ceramic coaxial and microstrip—that reduce the filter size, enhance its out-of-band selectivity and common-mode suppression, and allow for multiple levels of transfer function tuning. High selectivity is obtained in the differential mode due to the high number of poles and transmission zeros present. The common mode is highly suppressed through the introduction of additional transmission zeros and resistively loaded resonators. Furthermore, the use of ceramic coaxial resonators results in supplementary transmission zeros that are used to lower the out-of-band transmission in the differential mode. Multiple levels of tuning are obtained by reconfiguring only the frequency of the BPF's resonators. For experimental validation, a tunable mixed-technology microstrip prototype was manufactured and measured at S-band. It exhibited frequency tuning between 2.22 and 2.94 GHz, bandwidth tuning between 104 and 268 MHz, and an intrinsically switched-off mode with isolation >50 dB in the differential mode. For all states, the common mode was suppressed by at least 35 dB at the center frequency and within a wide range.

In this paper, the resonant frequencies, quality factors and bandwidths of high Tc superconducting circular microstrip patches in the presence of a dielectric superstrate loading have been studied using Galerkin testing procedure in the Hankel transform domain. The exact Green's function of the grounded dielectric slab is used to derive an electric field integral equation for the unknown current distribution on the circular disc. Thus, surface waves, as well as space wave radiation, are included in the formulation. London's equations and the two-fluid model of Gorter and Casimir are used in the calculation of the complex surface impedance of the superconducting circular disc. Galerkin testing is used in the resolution of the electric field integral equation. Two solutions using two different basis sets to expand the unknown disk currents are developed. The first set of basis functions used is the complete set of transverse magnetic and transverse electric modes of a cylindrical cavity with magnetic side walls. The second set of basis functions used employ Chebyshev polynomials and enforce the current edge condition. The computed values for a wide range of variations of superstrate thickness and dielectric constant are compared with different theoretical and experimental values available in the open literature, showing close agreement. Results are showing that the superstrate parameters should always be kept into account in the design stage of the superconducting microstrip resonators.

A super-wideband microstrip fractal antenna is designed with miniaturized dimensions of 21 mm × 23.5 mm × 1 mm and generation of dual rejection bands for WLAN/WiMAX systems has been achieved. The triangular fractal shape slots are placed inside a circular patch and the antenna is miniaturized by using a repetition frequency resonance technique. The proposed antenna frequency range 2.6–40 GHz operates for VSWR of less than 2. Two band rejections for the frequency ranges 5.1–5.8 GHz and 3.4–3.7 GHz are created by one enhanced slot at the feed line and one split-ring resonator at the back of antenna. HFSS 3D software was used for computer simulation. The proposed antenna is fabricated on the FR4 substrate with 1 mm thickness. The measurement data show good agreement with the simulation results.

In this paper, micromachined devices for millimeter-wave applications at U- and V-bands are presented. These structures are designed using a rectangular coaxial line built of gold-coated SU-8 photoresist layers, where the coaxial center conductor is suspended in air by stubs. The designs include a stepped coplanar waveguide (CPW)-to-coaxial transition at 63 GHz, with an insertion loss of 0.39 dB at 67.75 GHz and a return loss better than −10 dB across the band of operation between 54.7 and 70.3 GHz. Two filters have been designed; one centered at 42 GHz with a 10% bandwidth, and another at 63 GHz with a 5% bandwidth. Measured insertion losses of 0.77 and 2.59 dB were obtained for these filters, respectively. Measured return loss lower than 13.8 dB over the passband was achieved for both designs. The structures presented in this paper involve a low-cost manufacturing process suitable to produce integrated subsystems at millimeter waves.

The design of an analog frontend including a receiver amplifier (RX) and laser diode driver (LDD) for optical communication system is described. The RX consists of a transimpedance amplifier, a limiting amplifier, and an output buffer (BUF). An offset compensation and common-mode control circuit is designed using switched-capacitor technique to save chip area, provides continuous reduction of the offset in the RX. Active-peaking methods are used to enhance the bandwidth and gain. The very low gate-oxide breakdown voltage of transistors in deep sub-micron technologies is overcome in the LDD by implementing a topology which has the amplifier placed in a floating well. It comprises a level shifter, a pre-amplifier, and the driver stage. The single-chip frontend, fabricated in a 28 nm bulk-digital complementary metal–oxide–semiconductor (CMOS) process has a total active area of 0.003 mm2, is among the smallest optical frontends. Without the BUF, which consumes 8 mW from a separate supply, the RX power consumption is 21 mW, while the LDD consumes 32 mW. Small-signal gain and bandwidth are measured. A photo diode and laser diode are bonded to the chip on a test-printed circuit board. Electro-optical measurements show an error-free detection with a bit error rate of 10−12 at 20 Gbit/s of the RX at and a 25 Gbit/s transmission of the LDD.

In this paper, design and development of a via-free composite right/left handed transmission line (CRLH TL)-based diplexer for WiMAX and WLAN bands is reported. The diplexer is having two channels, where each channel consists of a separate bandpass filter (BPF). The BPF of both channels are designed on via-free CRLH TLs based on a newly proposed right-angled corner-modified split ring resonator (RAC-MSRR) structure. The RAC-MSRR incorporates meander paths because of which working scope of frequencies is focused for measured center frequencies (f1) 3.5 GHz with −3 dB fractional bandwidth (FBW) of 21.21% (BPF1 channel) and (f2) 5.6 GHz with −3 dB FBW of 13.29% (BPF2 channel). For diplexer design, T-section is used for joining two BPFs which results in very good isolation of more than 32.5 dB over the frequency band of 2.5–8.0 GHz. The designed diplexer has passband insertion loss of −0.87 dB at f1 and −1.25 dB at f2. Overall size of the fabricated diplexer including 50 Ω feed line is 18 × 15 mm2. Equivalent lumped circuit model parameters of the diplexer are obtained from the pseudo-inverse matrix technique. Measured results show good concurrence with simulated results and subsequently approve the proposed model design.

In this paper, multiple-input–multiple output (MIMO) antenna with dual-band frequency reconfiguration is presented. The proposed antenna consists of two symmetrical pentagon radiating elements. These radiating elements support bands of 1.5 GHz (GPS) and 2.4 GHz (Wi-Fi) frequency. The two PIN diodes are appropriately located on slot line in order to control the current flowing through the radiator. All simulated results are compared and confirmed with measured results. The antenna has VSWR ⩽1.8 and isolation of −28 dB. The advantage of this antenna is that bandwidth is increased by switching of PIN diode in the range from 80 MHz up to maximum 300 MHz. These characteristics demonstrate that proposed antenna is an attractive solution for a multimode application such as GPS, Wi-Fi routers, vehicular communication, etc. where wideband is required.