This paper describes some key points in the history and development of the European Microwave Conference, the European Microwave Week, and the European Microwave Association, starting from 1969. It captures the way in which the conference since the earliest days has sought to create a successful blend of scientific and industry interests and has adapted itself to and indeed shaped the many existing technical changes that have characterized and continue to be at the core of the field of microwave engineering.

This paper proposes the design of tunable dual-band resonators for multi-band multi-standard systems. The main objective is to provide frequency tunability in the second resonance while maintaining the first resonance fixed. To this end, two tunable resonators are proposed: the capacitive-loaded stepped-impedance resonator and the capacitive-loaded hole resonator. The work is divided into two main parts. In the first part, an in-depth analysis of the capacitive-loaded stepped-impedance resonator (SIR) structure is done; it provides analytical closed-form design equations that ease the resonator design in contrast to the several approaches available in the literature to date. The analysis is also particularized to the case of the capacitive-loaded constant-section resonator and extended to the capacitive-loaded hole resonator. In addition, a study of the quality factor in capacitively tuned SIRs is also provided. In the second part, resonators are integrated in three dual-band tunable filters, one based on the capacitive-loaded constant-section resonator, another one on the capacitive-loaded SIR, and finally on the capacitive-loaded hole resonator. Two of these filters demonstrate operation in wireless local-area network frequency bands, with a fixed first band at 2.45 GHz and a second band which can be tuned between 5.75 and 5.25 GHz.

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.

This work presents the design, manufacturing, and testing of three 5-bit K-band Micro-Electro-Mechanical-Systems (MEMS) phase shifters based on similar architectures (combination of switched line and loaded line) but employing different MEMS switch typologies (cantilevers and air bridges) and RF junctions (SP2T and SP4T). All devices have been monolithically manufactured on 200 µm thick high resistivity silicon substrate (4″) by using the Fondazione Bruno Kessler (FBK) RF MEMS process. The performance of the different devices has been compared in order to identify the best configuration to be implemented in electronically steerable phased array antennas for satellite COTM (communication on the move) terminals. Excellent performances were measured for the dielectric-free pad RF MEMS switches as well as the single bits constituting the phase shifter. The three 5-bit devices show return losses better than 15 dB for all states, with average insertion loss of 3.5 dB for the clamped–clamped, SP2T-based design, 2.2 dB for the cantilever, SP2T-based device and 2.1 dB for the cantilever, SP4 T-based design. A low-cost Surface Mountable Technology (SMT) one-level package has been developed as well to allow the phase shifter integration into phased array antennas by using automatic surface mounting techniques. The design and simulation of the SMT package are also presented together with its measured RF performance.

New technologies have resulted in transmission lines that deviate significantly from the intended rectangular cross sections. Trapezoidal cross sections and roughness that penetrate a significant depth into the surface in comparison to the skin-depth of the conductor can cause a very significant deviation in transmission line parameters from predicted values. Proximity effect further complicates the analysis by increasing losses and changing the impact of surface roughness by changing the current distribution. A skin-effect filament model that combines a traditional skin-effect filament modeling concept with traditional surface roughness modeling concepts is presented that accounts for surface roughness effects and non-ideal cross sections. The new technique models the transmission line non-idealities in a combined way with the current density in the signal and return current paths. This adapted filament model shows an average deviation of less than 2% above 1 GHz with one given transmission line measurement and does not have the computational challenges seen in a 3D full-wave solver.

We present here a new set of equations for modeling the I–V characteristics of Field Effects Transistors (FETs), particularly optimized for AlGaN/GaN HEMTs. These equations describe the whole characteristics from negative to positive breakdown loci, and reproduce the current saturation at high level. Using this model enables to decrease the modeling process duration when a same transistor topology is used for several applications in a T/R module. It can even be used for switches design, which is the most demanding application in terms of I–V swing. Moreover, particular care was taken to accurately model the first third orders of the current derivatives, which is important for multione applications. We also focused on an accurate definition of the nonlinear elements such as capacitances for power applications. There are 18 parameters for the main current source (and six for both diodes Igs and Igd). This can be compared to Tajima's equations-based model (13 parameters) or to the Angelov model (14 parameters), which only fit the I–V characteristics for positive values of Vds. We will detail here the model formulation, and show some measurements/modeling comparisons on both I–V, [S]-parameters and temporal load-pull obtained for a 8 × 75 μm GaN HEMT, with 0.25 μm gate length.

We introduce an integrated design methodology for the optimization of RF-to-DC conversion efficiency of multi-band rectennas (rectifying antennas), with the aim of harvesting the RF energy available in humanized environments. Existing RF sources can either operate at known frequencies, power budgets, and locations, or can be ubiquitously available at different frequency bands, and with unknown directions of incidence and polarizations. In all cases, the RF link power budget may be extremely low. In order to harvest a significant quantity of energy, it is thus mandatory to place a very special care in the design of each part of the receiving/storing system. For this purpose, the receiving antenna must be optimized together with the rectifying circuit and the load. In our work, this is accomplished by a rigorous design tool based on the concurrent use of nonlinear/electromagnetic (EM) CAD tools and EM theory. The effectiveness of the method is demonstrated by comparing the computed and measured performance of single- and multi-band rectennas, both linearly and circularly polarized. Such antennas are designed to harvest RF energy from a variety of cellular and WiFi systems that are normally present in civil environments.

This paper presents two compact slot array antennas for the 79 GHz automotive band integrated into a 28 µm thick benzocyclobutene (BCB) substrate attached to a 325 µm thick 5–20 Ω cm bulk resistivity silicon wafer. The two antennas are a transmit (TX) 1 × 8 slot array antenna with a size of 1 × 23 mm and a receive (RX) 8 × 8 slot array antenna with a size of 15 × 23 mm. Promising performance has been measured with the TX and RX subarray antennas (gain >4 dBi) with good matching to 50 Ω (RL > 10 dB) in the frequency range 70–90 GHz. By using a metal cavity, mounted on the back of the antenna, potential parallel plate or cavity modes could be reduced and the gain could also be increased by 2 dB. The measured and the simulated results are consistent.

This paper presents the design and implementation of an inverse class-F power amplifier (PA) using a high power gallium nitride high electron mobility transistor (GaN HEMT). For a 3.5 GHz continuous wave signal, the measurement results show state-of-the-art power-added efficiency (PAE) of 78%, a drain efficiency of 82%, a gain of 12 dB, and an output power of 12 W. Moreover, over a 300 MHz bandwidth, the PAE and output power are maintained at 60% and 10 W, respectively. Linearized modulated measurements using 20 MHz bandwidth long-term evolution (LTE) signal with 11.5 dB peak-to-average ratio show that −42 dBc adjacent channel power ratio (ACLR) is achieved, with an average PAE of 30%, −47 dBc ACLR with an average PAE of 40% are obtained when using a WCDMA signal with 6.6 dB peak-to-average ratio (PAR).

A highly integrated silicon platform (Hi-Mission) for high frequency applications is introduced. This platform utilizes heterogeneous Multi-Chip Module-Deposited (MCM-D) technology with integrated passive devices together with silicon and GaAs Monolithic Microwave Integrated Circuit (MMIC) technology developed for the automotive Ultra Wide Band (UWB) radar (short-range radar) frequency band from 77 to 81 GHz. Developments are described in the area of MCM-D process development, MMIC, integrated phased array antenna, module design, and assembly process development. The demonstrator is composed of two test vehicles designed for conducted and radiated measurements, respectively. Test results are presented at the component and module level.

Radio Frequency Micro-Electro-Mechanical System (RF-MEMS) represents a feasible solution to obtain very low power dissipation and insertion loss, very high isolation and linearity switch with respect to “solid state” technologies. In this paper, we demonstrate the full integration of RF-MEMS switches in the GaN-HEMT (Gallium Nitride/High Electron Mobility Transistor) fabrication line to develop RF-MEMS devices and LNA-MMIC (Low Noise Amplifier/Monolithic Microwave Integrated Circuit) prototype simultaneously in the same GaN wafer. In particular, two different coplanar wave (CPW) LNAs and a series of discrete RF-MEMS in ohmic-series and capacitive-shunt configuration have been fabricated. RF-MEMS performances reveal an insertion loss and isolation better than 1 and 15 dB, respectively, in the frequency range 20–50 GHz in the case of pure capacitive shunt switches and in the frequency range 5–35 GHz for the ohmic-series switches. Moreover, the GaN HEMT device shows an Fmax of about 38 GHz and a power density of 6.5 W/mm, while for the best LNA-MMIC we have obtained gain better than 12 dB at 6–10 GHz with a noise figure of circa 4 dB, demonstrating the integration achievability.

A novel scheme involving experimental analyses and diagnoses is presented for monitoring radio-frequency (RF) and high-speed circuits. A live electrooptic imaging (LEI) camera is used in the scheme and it provides real-time images of the phase evolution of the RF electric field. Besides, it is demonstrated that essential properties of RF wave propagation are easily grasped from visual images; examples of LEI movies and images from which such essential properties can be identified are presented. The subjects of the LEI observations, analyses, and diagnoses are planar RF circuits and a Gbps-class emitter-coupled-logic circuit. In addition, the results of analyses and diagnoses in the space domain are discussed.

Differential signaling is very common for high frequency integrated circuit design. Accurate multimode de-embedding at multigigahertz frequencies, however, is a major challenge. The differential and common-mode parameters can be obtained by converting the measured four-port nodal S-parameters into the mixed-mode form. Under certain conditions, it is possible to separate the modes and consider only the entries corresponding to the differential S-parameters. This allows to reduce the measured 4 × 4 matrix to a 2 × 2 matrix and consider the differential device as a two-port network. Thus, the standard de-embedding techniques, derived for two-port networks, can be applied to differential S-parameters. The purpose of this paper is to investigate the applicability of this approach for on-wafer measurements. We describe analytically the conditions under which this method is valid. As an example, a 2:1 transformer, manufactured in Infineon's 0.13 μm CMOS (complementary metal-oxide semiconductor) process, has been characterized. On-chip de-embedding structures have been fabricated using the same process. The results obtained using Short-Open, Thru-Line, and Thru-Line-Reflect de-embedding techniques are compared. Additionally, the results are verified by simulation of a device under test having high-mode conversion.

Taking into account sparsity of the reflectivity function of several radar targets of interest, efficient low-complexity automatic target recognition (ATR) systems can be designed. Such ATR systems would be based on two-dimensional (2D) spatial target models of low dimensionality, where critical information on the radar target signature is summarized. Discrete 2D radar target models can be estimated using high range resolution (HRR) data, measured at a sparse system of view angles. This being the main objective, incoherent tomographic processing of HRR data from a distributed surveillance system, made up of several radar nodes, is studied in this paper. A sparse angular sampling scheme is proposed, which exploits diversity due to both the distributed radar system and the target motion. The novelty is in the exploitation of this locally dense, but otherwise sparse set of viewing angles of the targets, obtained using a sparse network of radars. The de-ghosting efficiency of such a sampling scheme is demonstrated geometrically. This results in identification of minimal information resources for unambiguous estimation of a 2D target model, useful for radar target classification.

This paper presents an experimental investigation of two approaches to short-range radar imaging at microwaves by means of ultra-wideband (UWB) technology. The first approach represents a classical synthetic aperture radar (SAR) that employs a transmit–receive antenna pair on mechanical scanner. The second one makes use of a multiple input multiple output (MIMO) antenna array that scans electronically in the horizontal plane and mechanically, installed on the scanner, in the vertical plane. The mechanical scanning in only one direction reduces significantly the measurement time. Two respective prototypes have been built and compared. Both systems comprise the same 10–18 GHz antennas and multi-channel video impulse electronics while the same data processing and imaging method based on Kirchhoff migration is applied to acquired data for digital beamforming. The study has been done for an application of concealed weapon detection.

TanDEM-X (TDX; TerraSAR-X add-on for digital elevation measurement) is an innovative spaceborne X-band earth observation mission that will be launched in June 2010. This paper gives an overview of the TDX mission concept, summarizes the basic products and illustrates the achievable performance. In more detail the effect of quantization on the interferometric performance is discussed. Finally, new imaging techniques are outlined.

This paper presents the results of Doppler-polarimetric radar signal analysis, computer modeling, and real data processing that show the correlation between differential Doppler velocity (DDV), which is a difference between mean Doppler velocities measured at orthogonal polarizations of electromagnetic waves, and parameters of rain including both rain microstructure (parameters of drop-size distribution) and turbulence intensity in resolution volume. The reasonability to use DDV as one of the informative parameters in the recognition neural network system is checked.

This paper proposes a receiver that repeats iterative frequency-domain equalization (FDE) and decision-directed phase noise compensation (DD-PNC) to alleviate degradation due to the phase noise for millimeter-wave single carrier (SC) systems. High bit-rate SC-FDE transceivers based on the single-chip Si RF-CMOS IC technology in the 60-GHz millimeter-wave band have been extensively studied for wireless personal area network (WPAN) systems, and the relatively large phase noise in a phase-locked loop (PLL) synthesizer severely degrades transmission performance. In an initial processing of the proposed receiver, a cyclic prefix (CP)-based phase noise compensator (CP-PNC) removes the phase noise from a time-domain received signal by using CP, which is known to the receiver, and the channel is equalized by the iterative FDE using the conventional minimum mean-square-error (MMSE) weight. In an iterative processing, DD-PNC estimates the phase noise each symbol by exploiting an output of a channel decoder, and then compensates the time-domain received signal for the phase noise by using the estimate. In order to equalize the compensated received signal, the iterative FDE performs both the MMSE filtering and residual inter-symbol interference cancelation using the decoder output. Computer simulations following the 60-GHz WPAN standard demonstrate that in the 64QAM with the coding rate of 3/4, the proposed receiver with three iterations can drastically remove the phase noise of −85 dBc/Hz at 1 MHz offset, and that it can achieve excellent transmission performance.

This contribution deals with guided radar distance measurements in the field of industrial tank level control. The aim is to achieve a submillimeter gauging accuracy even when conducting the measurement within a highly dispersive environment of large and thus overmoded circular waveguides. Normally, multimode propagation causes a decrease in measurement precision. Therefore, the effects of intermodal dispersion are fundamentally reviewed and, based on these results, a correlation-based signal processing method is presented. This method is able to exploit the otherwise parasitic dispersion effects to enhance the measurement precision even in constellation with a simple waveguide transition or antenna, respectively. Furthermore, considerations on the mode variety and its influence on the signal complexity as well as investigations on the technique's reliability and accuracy are presented. Measurement results in a frequency range of 8.5–10.5 GHz are provided for three different kinds of waveguide transitions proving the capability of the method.