This paper presents the work carried out to assess the feasibility of miniature directive antennas. It is based on an analysis of the physical limits of antenna directivity in general and in particular as a function of their compact dimensions. A state of the art is done to identify and classify techniques to increase the directivity of compact antennas.

This work presents a wideband amplifier, in 12?19 GHz frequency range, with noise figure lower than 1.35 and 26 dB of gain developed in the frame of European Component Initiative program, supported by European Space Agency. By using a flexible biasing, this amplifier allows us to reach a significant linearity, output power at 1 dB compression up to 19 dBm, or to reduce the DC consumption close to

In this paper, we report a new high-speed and high-power switching circuit based on GaN HEMT's. The elementary switching cell, composed of two GaN HEMT's and two resistors, acts like a power threshold comparator with high-output voltage. Theoretical analysis of static and dynamic circuit operation points out the dependence of efficiency and switching speed to the main circuit elements. Four switch

The silicon/porous silicon (PS) hybrid substrate is an interesting candidate for the monolithic integration of radiofrequency (RF) circuits. Thus, passive components can be integrated on the insulating PS regions close to the active devices integrated on silicon. Regarding silicon, hybrid substrates allow the improvement of RF circuits performances. To demonstrate it, coplanar waveguides have been

Implantable antennas have recently been receiving substantial attention for medical diagnosis and treatment. In this paper, a coplanar waveguide-fed monopole antenna for industrial, scientific, and medical (ISM) band biomedical applications is proposed. The antenna has a simple structure is placed on human tissues such as muscle, fat, and skin. The designed antenna is made compatible for implantat

We present a study on using carbon nanotubes (CNTs) as the radiating part of resonant antennas in order to reduce their dimensions. A mesoscopic electromagnetic (EM) model for CNTs was developed to allow the simulation of RF devices in classical EM solvers while retaining the specific properties of CNTs. A circuit approach is also used to provide a physical interpretation of the results on monopol

In the present paper, we present a dynamic gate biasing technique applied to a 10 W, S-band GaN amplifier. The proposed methodology addresses class-B operation of power amplifiers that offers the potential for high efficiency but requires a careful attention to maintain good linearity performances at large output power back-off. This work proposes a solution to improve the linearity of class-B amp

This paper outlines an original shape optimization library backed by a three dimensional (3D) full-wave electromagnetic (EM) simulator, combining several efficient structural optimization techniques and suitable for viable computer-aided design (CAD) of complex microwave components. The microwave components are modeled by finite element method (FEM) and their dimensions and shape are optimized usi

An accurate and very large band (30?110 GHZ) lumped element equivalent circuit model of capacitive RF-MEMS components based on a standard 250 nm BiCMOS technology is presented. This model is able to predict the effect of the fabrication process dispersion, synthesize new components and monitor the failure mechanisms. Moreover, a reliability study is performed in order to define a screening criteri

In the present work, a novel multistrip monopole antenna fed by a cross-shaped stripline comprising one vertical and two horizontal strips has been proposed for wireless local area network (WLAN)/Industrial, Scientific, and Medical band (ISM)/International Mobile Telecommunication (IMT)/BLUETOOTH/Worldwide Interoperability for Microwave Access (WiMAX) applications. The designed antenna has a small