This paper focuses on multi-radio front-end transmitter, a function implied by cognitive radio (0.5–6 GHz). S and C bands standards (wireless local and metropolitan area networks) present a challenge, due to the signal modulation schemes (orthogonal frequency division multiplex (OFDM)/WCDMA, wideband code division multiple access) dynamic (tens of dBs), driving us to a mandatory transmitter linearization. The idea is to provide frequency, flexibility, and average power control of a multi-radio high-efficiency front end for such signals (polar/envelope elimination and restoration (EER) structure). The study implies antennas design and average power control demonstration. Based on a switched mode power amplifier (PA), a discrete detuning is possible to adapt the PA at both “WiMAX” and “Wifi5” frequencies. This architecture amplifies signals with amplitude information. This is coded here by the ΣΔ/PWM (pulse width modulation) technique, to present a constant envelope signal. The amplitude information is restored by a pass-band radio frequency (RF) filter. The antenna can be designed with a notch, to reduce the filtering constraints (selectivity and standards coexistences) and to help in the restoration of amplitude information. Average power control is illustrated by voltage supply variation and results are a possible dynamic of 9.5 dB. To complete the analysis, the simulation of the propagation channel, including antennas, with CST (free space, line of sight) is imported under AGILENT-ADS.

The electrical modeling of power packages is a major issue for designers of high-efficiency hybrid power amplifiers. This paper reports the synthesis and the modeling of a packaged Gallium nitride (GaN) High electron mobility transistor (HEMT) associating a nonlinear model of the GaN HEMT die with an equivalent circuit model of the package. The extraction procedure is based on multi-bias S-parameter measurements of both packaged and unpackaged (on-wafer) configurations. Two different designs of 20 W packaged GaN HEMTs illustrate the modeling approach that is validated by time-domain load-pull measurements in S-band. The advantage of the electrical modeling dedicated to packaged GaN HEMTs is to enable a die-package co-design for power matching. Internal matching elements such as Metal oxide semiconductor (MOS) capacitors, Monolithic microwave integrated circuits (MMICs), and bond wires can be separately modeled to ensure an efficient optimization of the package for high power Radio frequency (RF) applications.

We present a design strategy for a buck converter, which fulfills the high dynamic requirements of efficient envelope amplifier needed by modern efficiency enhancement techniques for power amplifiers. The proposed DC–DC converter has an innovative control system, which makes it fast, robust, and resource saving. A mathematical model describes its dynamic behavior and is used to find a setup, which gives an optimal compromise between the dynamic performance and efficiency. The approach is applicable to various state-of-the-art communication standards. As an example, an envelope following (EF) power amplifier (PA) for the wideband code-division-multiple-access (W-CDMA) modulation scheme is treated. The corresponding buck converter is implemented in a monolithic chip (except the inductor and the capacitor of the output filter). The measurements with an industry standard W-CDMA PA (RMPA2265) match very well with the forecast of the model and confirm doubling of the average efficiency.

In this paper, a new methodology to compare the robustness of sensor structures employed in radiofrequency design for test (RF DFT) architectures for RF integrated circuits (ICs) is proposed. First, the yield loss and defect level of the test technique is evaluated using a statistical model of the Circuit under Test (obtained through non-parametric statistics and copula theory). Then, by carrying out the dispersion analysis of the sensor architecture, a figure of merit is established. This methodology reduces the number of iterations in the design flow of RF DFT sensors and makes it possible to evaluate process dispersion. The case study is a SiGe:C BiCMOS LNA tested by a single-probe measurement.

This paper proposes a systematic approach for designing and modeling letter-shaped microstrip ground slots. Twenty-three structures are investigated. For each one, a geometrical circuit model is developed. Interestingly, 21 letters have unique s-parameters (electromagnetic [EM] print). Results are confirmed by EM simulations and measurements. These results may pave the way to new applications, e.g. microwave character recognition, letter-based microwave circuits, or new radio frequency identification (RFID) structures

A new structure is proposed in this article, to operate as wideband and wide-angle flat Radome. In this structure several dielectric and ferrite layers are placed successively, one next to the other, to behave as a matched layer. First, the relationship between the permittivity and permeability of a required fictitious mixed material is obtained. Then the required permittivity and permeability of dielectric and ferrite layers are obtained at desired incidence angle. The performance of the proposed structure is investigated and validated using some theoretical and simulation examples.

New Global Navigation Satellite System (GNSS) systems under development, such as Galileo, are very promising for future global positioning-based applications. A vast research is undergoing a final stage of implementation in order to fulfill the primary purpose of European Space Agency for developing and then sustaining of 30 (27 + 3 spares) Galileo satellites in orbit. This article presents simulation results for a realistic deployment of multibeam antennas, with a new modified theoretical pattern, in GNSS Satellite Systems. The proposed multibeam antennas use 61-spot beams for maximum efficiency in terms of satellite coverage and accessing high quality of service. In order to prove the reliability and feasibility of this work, various simulations were conducted using the upcoming Galileo system as a platform taking into consideration real-world conditions. Gain analysis versus elevation, Bit Error Rate (BER) and access time simulation results show that the viability of the proposed multibeam antenna deployment is established.

In the present study, the essential oil from the leaves of River Red Gum (Eucalyptus camaldulensis Dehnh) was distilled by microwave applied in situ hydrodistillation (MWHD) and the properties obtained were compared with hydrodistillation (HD) techniques. The chemical composition of essential oil obtained by the microwave method was analyzed by gas chromatography (GC) and GC–mass spectrometry (MS). The results showed that the essential oil from E. camaldulensis could successfully be distilled by using microwave irradiation power. Microwave power has been supplied from a cavity having a multimode microwave reactor 2455 MHz with a maximum power of 1000 W. Electromagnetic power distribution has been analyzed inside the cavity. The yield of essential oil increased with increasing microwave irradiation power. It was also found that the content of main compounds clearly varied according to methods applied. However, the yield of essential oil determined by MWHD was slightly lower than that of conventional HD method at conditions studied.

The radiofrequency (RF) system of the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a resonant system based on the quarter-wave cantilever-type resonating structure. Power is fed to the Dee from the anode of the 500 kW RCA 4648 tetrode tube operating in grounded cathode configuration, which is coupled to the side of the Dee stem. The tube is obsolete and makes its continued use impractical. A new final power amplifier was designed and built using the commercially available tube Eimac 4W150,000E. The new amplifier was successfully commissioned and has been reliable and easy to operate.