In this paper a novel differentially fed Ultra-Wide Band (UWB) antenna in low-temperature co-fired ceramics (LTCC) technology to be used in the 60 GHz band for integrated RF front-ends is presented. The antenna is based on the aperture stacked patch fed via H-shaped aperture to achieve more than 10 GHz operational bandwidth. The antenna is fed by a parallel-wire transmission line which enables the antenna to be directly integrated with differential Monolithic Microwave Integrated Circuits (MMICs). To alleviate influence of the surface waves (efficiently excited in LTCC material due to its high dielectric constant) on the antenna radiation and realize uni-directional radiation patterns, a dedicated shield is added to the antenna. The measured results of the shielded antenna showed that the antenna has an operational bandwidth from 51 GHz to over 65 GHz, the gain is about 3.5–8 dBi, and −5 dB beamwidth is about ±30°. The measurement results also demonstrated that the shield indeed improves the antenna impedance bandwidth, gain, and radiation patterns substantially.

This paper presents the results of direct rain attenuation measurements carried out on four experimental microwave links, installed at UTM, Malaysia. The links operate at frequencies of 15, 22, 26, and 38 GHz and the cumulative distribution function for different rain rates have been generated from the measured 4-year rain gauge data. The experimentally measured attenuation data have been compared with International Telecommunication Unior-R rain attenuation predictions; and it has been found that the latter have underestimated the measured values, especially at higher rain rates. The deviations have been modeled as a function of rain rate exceedances R%p. It is hoped that the study will provide useful information for estimation of rainfall attenuation on microwave links in tropical regions that have similar situation to Malaysia.

This paper reports the effect of suspended periodic defect structure in switching the frequency of ring resonator. It has been observed in simulations and experiments that this non-intrusive method can switch the frequency by 31 MHz for square lattice of suspended periodic defect and by 124 MHz for a triangular lattice of suspended periodic defect structure.

This work describes the integration of Schottky diodes into fast GaN MMIC process technology suitable for the realization of switch-mode power amplifier core chips for class-S operation at 2 GHz. With the demonstration of this technology, the so-called third-quadrant issue, which reduces the efficiency in band pass-Δ-Σ class-S operation can be diminished on device level. Compared to a hybrid diode assembly, the broadband properties of the amplifier module with on-chip-integrated diode can be improved by the reduction of parasitic losses. The GaN heterostructure field effect transistors (HFETs) with integrated series diode show a cut-off frequency of 28 GHz with drain breakdown voltages exceeding −100 and +100 V and comparable large signal performance to conventional GaN HFETs at 10 GHz. MMIC core chips for class-D and class-S switch-mode power amplifier modules are demonstrated for the operation at mobile communication frequencies between 0.45 and 2 GHz and signal bit rates up to 8 Gbps. The circuits yield broadband output power levels between 4 and 9 W with efficiencies of up to 80%.

Atmospheric and higher pressure RF and microwave plasma sources have numerous applications including material processing and spectroscopy. More recently, advantages in using such discharges for combustion ignition are being investigated. A particularly simple and compact microwave discharge generating device is the quarter wave coaxial cavity resonator (QWCCR). This paper presents a new, compacted design of such a device. A simple approximate analysis of the quality factor, Q, which is a measure of the resonant electromagnetic potential step-up capability is given, and compared to experimentally measured quality factors showing reasonable agreement. Analytic results indicate that the foreshortened folded cavity quality factors are comparable to tapered coaxial cavity designs.

Antenna on chip (AoC) and antenna in package (AiP) solutions for millimeter-wave (mmWave) applications and their characterization are presented in this paper. Antenna integration on low resistivity (LR) and high resistivity (HR) silicon substrate are expected. And, in a packaging approach, the combination of antenna on silicon with a material, which has the effect of a “lens”, allowing increasing gain is presented. In a second part, to satisfy beamforming capabilities, a hybrid integration of the antenna on silicon and glass substrates is proposed.

In this paper a dual-band bandpass filter with sharp rejection is proposed. The filter is realized by using two half-wavelength stepped impedance resonators to operate at the passbands 2.5 and 3.5 GHz. To increase the band width further to about 45 MHz at the lower passband and 115 MHz at the higher passband, interdigital capacitors are introduced between resonator and input and output combining network. Measured insertion loss is about 1.45 and 1.7 dB at first and second passbands, respectively. A finite transmission zero in between two passbands at 2.84 GHz is realized to improve the selectivity of the filter. The design procedure to get highly selective response of the proposed filter is explicitly explained. An equivalent circuit model of proposed filter is developed that matches well with measured results.

Burst mode operation is proposed as an efficiency improving technique for power amplifiers. The core idea is to modulate the amplitude of the envelope signal into a series of square-wave pulses such that the width of the signal burst or the total amount of pulses are varied according to the envelope. The phase information is still contained by the timing of the pulses. This work presents the efficiency and linearity analysis of burst mode radio frequency (RF)/power amplifier (PA). In addition, the efficiency performance is compared when the burst mode RF power amplifiers (PA) is connected to a wideband load or a narrowband filter. It is shown that burst mode PAs are more efficient than the conventional Class B PAs. To achieve an even more favorable efficiency, a transmission line is inserted between the output of the switching RF PA and the filter to improve the filter's impedance characteristic. Additionally, the efficiency and linearity of the burst mode PA with and without transmission line has been studied and simulated thoroughly. To demonstrate the validity of the efficiency formulas and linearity considerations, a printed circuit board (PCB)-mounted burst mode PA using a laterally diffused metal oxide semiconductor (LDMOS) transistor was fabricated. Measurements show a peak efficiency of 78% and 28.8 dBm of output power.

A novel wideband transition from finite ground-conductor backed-CPW (FG-CB-CPW) to microstrip has been demonstrated in 8–23 GHz band. Proposed transition provides a very low-loss alterative to microstrip/coplanar lines at higher frequencies. Simulated results are detailed for both alumina and silicon substrates. Simulated results are validated on alumina substrate providing more than 100% bandwidth with maximum insertion loss of around 1.5 dB in the targeted frequency range. Comparison of the results along with design procedures is detailed in this article.

The large bandwidth of the 60 GHz frequency band enables wireless short-range applications with data rates of several Gbit/s. The German project EASY-A has focused on early prototype implementations for selected applications, although no generally accepted 60 GHz standard has been available at the time. The implementations are based on application-oriented physical layer designs and link-budget investigations that account for the scenario-specific channel characteristics and for different integration technologies. This paper discusses the results of these investigations and details the hardware implementation of the digital baseband processing that relies on considerable parallelization. The link-budget results show that SiGe technology allows for 1 Gbit/s at a range of 3.5 m in non-line-of-sight environments, while up to 10 Gbit/s are feasible at more than 1 m in case of strong line of sight.

The high millimeter-wave (mmW) frequency range offers new possibilities for high-resolution imaging and sensing as well as for high data rate wireless communication systems. The use of power amplifiers of such systems boosts the performance in terms of operating range and/or data rate. To date, however, the design of solid-state power amplifiers at frequencies about 210 GHz suffers from limited transistor model accuracy, resulting in significant deviation of simulation and measurement. This causes cost and time consuming re-design iterations, and it obstructs the possibility of design optimization ultimately leading to moderate results. For verification of the small-signal behavior of our in-house large-signal transistor model, S-parameter measurements were taken from DC to 220 GHz on pre-matched transistors. The large-signal behavior of the transistor models was verified by power measurements at 210 GHz. After model modification, based on process control monitor (PCM) measurement data, the large-signal model was found to match the measurements well. A transistor model was designed containing the statistical information of the PCM data. This allows for non-linear spread analysis and reliable load-pull simulations for obtaining the highest available circuit performance. An experimental determination of the most suitable transistor geometry (i.e. number of gate fingers and gate width) and transistor bias was taken on 100 nm gate length metamorphic high electron mobility transistor (mHEMT) transistors. The most suitable combination of number of fingers, gate width and bias for obtaining maximum gain, maximum output power, and maximum power added efficiency (PAE) at a given frequency was determined.

This paper reports a new compact dual-band axially corrugated profiled horn feed (DBCPH) for prime-focus reflector antenna at C-band (uplink and downlink frequency bands with bandwidth ratio of 1.6). DBPCH consists of one sinusoid profiled section and two internal axial corrugations (internal short-circuited ring slots), for obtaining a multimode horn feed. Such a blended structure is optimized over the specified frequency bands (3.68–3.70 and 5.865–5.915 GHz) to achieve various performance objectives (such as compactness, return loss, polarization purity, etc.). Measured and predicted results show that DBCPH provides better return loss >18.6 dB, low cross-polarization (better than −32 dB), and adequate edge taper at ±48° (8.5–11.7 dB) along with compact size (1.3λ aperture diameter and 0.88λ length at lower frequency). The horn would be used as a feed element for front-fed prime-focus reflector for pencil beam spacecraft antenna application.

A 160-GHz SiGe-HBT (Heterojunction Bipolar Transistor) down-conversion receiver front-end for use in active millimeter-wave imaging arrays and D-band communication applications is presented. The monolithic front-end consists of a three-stage low-noise amplifier providing 24 dB of gain and a Gilbert-cell mixer capable of operating from a −8-dBm LO signal. A fully differential architecture compatible with balanced on or off-chip antennas is used to avoid the need for on-chip baluns in antenna-integrated applications. The implemented downconversion front-end consumes 50 mA from a 3.3 V supply and requires a 0.1 mm2 die area (excl. pads) per channel. With a 160-GHz input signal and an Intermediate Frequency (IF) of 1 GHz, the implemented front-end yields a 25-dB conversion gain, a −30-dBm input compression point, and a 9-dB/7-dB (with/without auxiliary on-chip input balun) system noise figure.

This article presents measurement and analysis results for 60 GHz short-range wideband radio channels. We consider two scenarios, referred to as “very-high-rate extended-range” (VHR-E) and “ultra-high-rate cordless” (UHR-C). The VHR-E measurements aimed at 60 GHz fixed networks for an Airbus A340 cabin both under static and dynamic (shadowing due to passenger movement) channel conditions. We describe the channel sounder used for the VHR-E measurements and present a simple multipath model derived from the measurements. Furthermore, simulations show the feasibility of the ray-tracing approach for this kind of channel. As a typical UHR-C use case, a data kiosk scenario was investigated. Various propagation conditions are analyzed with respect to channel gain, time dispersion, and frequency selectivity.

In this paper, it is proposed to use a cylindrical cell for the characterization of dielectric material. The extraction of complex permittivity is based on inverse gradient approach where the full-wave simulation results are mapped to experimental data to extract the complex permittivity. As the operational frequency of radio frequency (RF)/microwave devices is increased, it becomes difficult to accurately model waveguide transitions using traditional methods based on meshing such as finite-element method (FEM) where mesh size is determined according to the wavelength. Moreover, these techniques usually require extensive computational resources. Mode matching technique (MMT) is the full-wave tool implemented in this current work. It is used to compute the generalized scattering matrices (GSMs) of the different discontinuities of test setup. These GSMs model precisely discontinuities as they include the effects of all higher-order modes propagating and evanescent. Simulation and experimental results are included to validate the proposed approach for the rigorous modeling of those discontinuities and hence the extraction of complex permittivity.