Yorgos Stratakos

T his article discusses the design and devel-opment of a novel Ka band power ampli-fier. The amplifier has a gain of 25 ±1.5 dB, an output power of 1.5 watts at 1 dB com-pression and a power-added efficiency of 25 per-cent. The frequency range is 25 to 32 GHz. The amplifier is housed in an aluminum box with an associated heat sink for long life operation. The input is a 2.9 mm female connector and the out-put is a WR-28 waveguide adapter. The design incorporates three power MMICs from Fujitsu Quantum Devices. The developed module can be incorporated into a waveguide combiner to achieve higher output levels. This amplifier is useful for the output stage of transmitters for satellite base stations. Experimental results are shown with S-parameter measurements and output power levels. Design specifications — measurements The rough block diagram of the amplifier is shown in Figure 1. It is comprised of one stage of FMM5804X and parallel ES/FMM5803X. Both MMICs are products of Fujitsu Mic...

T his article discusses a low-cost homodyne hybrid multichannel multipoint distribu-tion service (MMDS) upconverter. The design of the radio frequency (RF) bandpass fil-ter shows a sharp out-of-band response and, therefore, permits the use of a single phased-locked oscillator for the upconversion of the intermodulation frequency (IF) signal to the total MMDS band (2.3 to 2.7 GHz). Two separate bands for the MMDS standard are common: one from 2.3 to 2.5 GHz and the other from 2.5 to 2.7 GHz. The new system was developed on a low-cost Rogers RO4003 sub-strate material in microstrip, except for the fil-ter, which was implemented in stripline geome-try. The spurious emissions of the upconverter were well below 55 dBc and the intermodulation distortion (IMD) performance was excellent.

ABSTRACT The circuit and coupling properties of a dipole grid array placed inside a rectangular cross-section waveguide are analysed when also a rectangular aperture is used to couple the resonator energy into a semi-infinite waveguide. A Green function approach is employed to determine the current distribution on the dipole elements by solving an integral equation and taking into account the boundary conditions on the rectangular cavity walls. Both mutual and self-impedance terms are calculated for the dipole grid array, and the effects of the rectangular coupling aperture are also examined. © 1997 by John Wiley & Sons, Ltd.

I. INTRODUCTION ASSIVE imaging techniques use only naturally generated signals from the body and are therefore entirely safe for the subject. In this context, a Microwave Radiometry Imaging System (MiRaIS) has been developed in the Microwave and Fiber Optics Laboratory of ...

ABSTRACT In this paper the design of a MMIC low noise amplifier at 10 GHz is presented using Computer Aided Design (CAD) techniques. The foundry used for the fabrication of the chip is GEC-Marconi F20 process. This process has Ft=24 GHz and an associated gain of 10 dB with minimum noise figure of 1.6 dB at 12 GHz. The LNA is a two stage design where source peaking techniques have been used in order to have an acceptable level of unconditional stability in the whole frequency range from DC-20 GHz. The area of the chip is 2 mm2, the two stage gain is 10 dB at 10 GHz, the noise figure obtained is almost 2 dB and the input and output return loss is better than 10 dB. The chip is designed to work in a low noise radar receiver. Experimental results are also measurements using a CASCADE wafer probe station concerning both linear (S-parameters, noise figure) and nonlinear measurements (power gain compression, spectrum). Very good agreement between theoretical and experimental results have been noticed due to the very good simulator used (MDS=Microwave Design System) as well as due to the very good smart libraries offered by GEC-Marconi

ABSTRACT Monolithic Microwave Integrated Circuits (MMICs) and Microstrip Antennas (MSA) technologies are used in the design and development of a cylindrically shaped conformal array system as presented in Kanno er al (1)(4)(6) operating at X-band to be used for mobile communications, as well as remote sensing - radar applications. A novel hybrid Method of Moments and Method of Auxiliary Sources technique is employed to design the printed antenna array on the curved surfaces. MMICs are designed for the QPSK modulator/demodulator using the F20 GaAs foundry process of GEC-Marconi as described in (15) in the framework of the EUROPRACTICE Action. Low noise and power amplifier as well as the diplexer filters and the circulator have been designed based on MIC technology on TEFLON R4003 substrates. An IF band signal processing is employed for phase shifting of the array elements, without using amplitude control at the first stage.

ABSTRACT Angle tracking noise in monopulse tracking radars has been an important study topic during the last decades. This phenomenon otherwise known as "Glint" is studied in present article assuming the presence of a non-perfect interferometer transponder placed on a target with a non-zero radar cross section. The effects of interferometer angle and amplitude balance and the target echo signal strength is analyzed theoretically and numerical results are computed and presented for a wide set of parameter values. The required power ratio of interferometer and echo signals to achieve significant angle noise is derived. Numerical results and analytical approximations of the angle noise are presented in the form of parametric curves.

ABSTRACT The design and development of a novel dual-band coplanar waveguide (CPW)-fed bow-tie shaped slot antenna for broadband wireless applications is presented. The antenna operates in IEEE 802.1 1b (2.4-2.5 GHz) and 802.11 a (5.1-5.9 GHz) frequency bands and is aimed to cover a gap in the multi-band wireless applications domain. Simulation work has been performed using commercially available three-dimensional electromagnetic tools and prototypes have been built in order to explore the actual performance of this novel antenna. Satisfactory agreement in simulation and experimental results is shown. The antenna can easily be attached on the backplane of PDAs (Personal Digital Assistants), smartphones or notebooks, to meet the users' needs for wireless connectivity in a small form factor.

The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings. To reduce the impact of installation and management, data will be transmitted to a remote base station using a wireless interface. During the project, sensor prototypes were produced by assembling pre-existing components and by developing ex-novo miniature devices with ultra-low power consumption and sensing performance beyond that offered by sensors available on the market. The paper outlines the device operating principles, production scheme and working at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, back to back with reference devices, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The paper assesses the economical sustainability and performance of the sensors developed for the project and discusses their applicability to long-term seismic monitoring.

The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings and will transmit data using a wireless interface. During the first phase of the project completed so far, sensor prototypes were produced by assembling preexisting components. This paper outlines the device operating principles, production scheme and operation at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The performance of the sensors developed for the project and their applicability to long-term seismic monitoring are discussed.