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International audienceIn this paper, a compact diplexer based on coupled stepped impedance resonators (SIRs) is designed for Digital Communication System and the industrial, scientific and medical applications. The diplexer is composed from two band-pass filters operated at 1.8 and 2.45 GHz respectively. The size and the position of the SIR and the feed lines are determined through the theoretical design and the simulation. The diplexer has less than 2.2 dB insertion loss and more than 21 dB of isolation. The diplexer performances are investigated numerically by using Momentum ADS Agilent and CST microwave software.The electromagnetic simulated results of the proposed diplexer show a good agreement with the measured results

In this paper design of microstrip patch antennas are presented for ultra wideband (UWB) applications. The designed antennas have good matching input impedance in a wide frequency band covering the UWB frequency band which is defined by the FCC. The proposed antennas consist of rectangular patch which is fed by 50Ω microstrip line. These antennas are investigated and optimized by using CST microwave studio, they are validated by using another electromagnetic solver HFSS. The proposed antennas are designed and optimized taking into account the optimized of the ground by using Defected Ground Structure (DGS) in order to improve the frequency band of microstrip antenna. Hence, the impedance and surface current of the antenna structures are affected by DGS. As will be seen, the operation bandwidth of the proposed antennas is from 3 to 15 GHz (return loss≤-10 dB), corresponding to wide input impedance bandwidth (133.33%), with stable omnidirectional radiation patterns and important gain. A good agreement has been obtained between simulation and measurement results in term of bandwidth clearly show the validity of the proposed structures. These antennas are useful for UWB applications, may be able to potentially minimize frequency interference from many wireless technologies i.e WLAN, WiMAX. Details of the antennas have been investigated numerically and experimentally.

RF/microwave power amplifier (PA) is one of the components that has a large effect on the overall performance of communication system especially in transmitter system and their design is decided by the parameters of transistor selected. This letter presents a new concept of a wide-band microwave amplifier using scattering parameters that is often used in the radio frequency communication systemas an application of the active integrated antenna [1][2]. This power amplifier operates from 1.75 GHz to 2.15GHz frequency and it is based on AT-41410 NPN transistor that has a high transition frequency of 10GHz. The proposed Single Stage PA is designed by microstrip technology and simulated with Advanced Design System (ADS) software. The simulation results indicate good performances; the small power gain (S21) is changed between 11.8 and 10dB. For the input reflection coefficient (S11) is varied between -11 and -22.5dB. Regarding the output reflection coefficient (S22) is varied between -13.1 and -18.7dB over the wide frequency band of 1.75-2.15GHz and stability without oscillating over a wide range of frequencies.

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This work deals with the design, simulation, fabrication and experimentation of a novel 2.45 GHz rectifier for wireless power transmission applications. We have designed a voltage multiplier topology rectifier including 5 Schottky diodes known by their low threshold. This rectifier could perform a wireless power supply for many cases where the use of batteries or wires is impossible due to many limitations. The circuit was analyzed and optimized with the Harmonic Balance method provided by the Advanced Design System (ADS). Good performances are observed through the simulated results and confirmed by the fabrication tests in terms of RF-DC conversion efficiency, DC output voltage level and matching input impedance.

The aim of this paper is to use defected ground structures (DGS) in order to miniaturize a microstrip patch antenna. The DGS structure is integrated in the ground plane to improve the performance of the planar antenna, and shifted the resonance frequency from 5.8 GHz to 2.5 GHz, with a miniaturization up to 83%. The antenna is designed, optimized, and miniaturized by using the CST MWstudio, mounted on an FR-4 substrate having a dielectric constant 4.4, a loss tangent tan (ɸ)=0.025, thickness of 1.6 mm with the whole area of 34X34 mm2.The proposed antenna is suitable for ISM (Industrial, Scientific and Medical) applications at 2.5 GHz with S11 ≤(-10) dB. The antenna is fed by 50ohm input impedance and it has good performances in terms of matching input impedance and radiation pattern. The proposed antenna was fabricated and tested.Simulation and measurement results are in good agreement.

This paper presents the design of new compact antennas for ultra wide band applications. Each antenna consists of a rectangular patch fed by 50Ω microstrip transmission line and the ground element is a defected ground structure (DGS). The aim of this study is to improve the bandwidth of these antennas by using DGS and the modification geometry of rectangular structure, which gives new compact antennas for UWB applications. The input impedance bandwidth of the antennas with S11<-10dB is more than 10GHz, from 3GHz to more than 14 GHz. The proposed antennas are investigated and optimized by using CST microwave studio, they are validated by using another electromagnetic solver Ansoft HFSS. The measured parameters present good agreement with simulation. The final antenna structures offer excellent performances for UWB system.