Modelo electrotérmico gran señal de la fuente de corriente Ids de los transistores GaAs MESFET y HEMT

This paper describes an accurate approach to modelling the effect of ambient temperature (from -70ºC to +70ºC) on the I/V characteristics of the drain to source Ids current source of Gallium Arsenide (GaAs) MESFET and HEMT transistors under DC and/or pulsed operation. The proposed approach can be applied to any existing DC drain to source current models to increase their accuracy and rang of operation. Starting from a single-current source model, based on the I/V DC and pulsed measurements, a new model allows the user to simulate both DC and large signal behaviour of the device over a range of temperature is presented. This model takes into account all the second order effects (frequency dispersion, self-heating due to the operating point and ambient temperature effect) present in this kind of devices. The accuracy of the proposed approach will validate when comparing the simulation with experimental results

A new compact small circular patch antenna for UWB communication

A new small circular patch antenna for ultrawideband (UWB) applications is presented. By studying this structure, it is shown that the insertion of a slot with the desired length and width in the ground plane, can lead to a large bandwidth. Our antenna, whose dimensions are 18×12×1.58 mm3, was fed by an SMA female connector with characteristic impedance of 50Ω in order to measure the return loss and VSWR and to compare them with the simulation results. The bandwidth obtained from measurements ranges from 3.52 to 13.67 GHz for VSWR < 2 and from 3.26 GHzto14.23GHz for VSWR < 3. The radiation pattern is omnidirectional on most of the operating band. High Frequency Structure Simulator (HFSS) was used for simulation whose results are in good agreement with the measured parameters

Dispersion uncompensated IM/DD transmissions of 12GHz-wide multi-band OFDM over 100km with a D-EML

International audienceGeneration of optical SSB signals by a D-EML is extended to its whole bandwidth. In an SSB context, 12GHz multi-band OFDM signal is transmitted through 100km intensity modulation/direct detection dispersive channel without frequency fading

Determination of the complex permittivity of each layer for a bi-layer dielectric material using transmission (ABCD) matrix in Ku-Band frequency

A new technique is presented to determine the complex permittivity of each layer for a bi-layer dielectric material. The bilayer material sample is loaded in a Ku-band rectangular waveguide WR62 and its two port S-parameters are measured as a function of frequency using the E8634A Network Analyzer. Also, by applying transmission (ABCD) matrix, expressions for the S-parameters of the bi-layer dielectric material as a function of complex permittivity of each layer are developed. To estimate the complex permittivity of each layer’s dielectric material, the square sums of errors between the measured and calculated S-parameters are minimised using a nonlinear optimization algorithm. The complex permittivity of each layer for a bi-layer dielectric material such as FR4-Teflon, FR4-Delrin and Delrin-Teflon are determined at the Ku-band frequencies, and the average relative errors between the individual dielectric materials and those of each individual layer of the bi-layer dielectric materials are calculated

Business Activity And Environmental Degradation In Mexico

This paper contributes to the literature by investigating the relationships between business activity, carbon dioxide (CO2) emissions, energy consumption in a developing country by taking into consideration the effects of ongoing industrialization and financial development. To do this, we introduce an innovative empirical approach based on ARDL bounds testing in the presence of structural breaks and apply it to Mexico over the period 1971-2011. We show strong evidence of cointegration between these variables. More interestingly, we find that energy is the long-run forcing variable to explain the Mexican business activity growth. This implies that energy savings policy may result in decreasing the national income or employment

A new method to determine the complex permittivity and complex permeability of dielectric materials at X-band frequencies

This paper presents a simple waveguide measurement technique to determine the complex permittivity and complex permeability of a dielectric material. The dielectric sample is loaded in the transmission line rectangular waveguide WR90. The S-parameters of the waveguide are measured by Network analyzer and calculated as a function of the complex permittivity and complex permeability using theory of transmissions lines. Using the MatLab Optimization Tools, a simple MatLab scripts is written to look for complex permittivity and complex permeability of a dielectric material so as to match the measured and calculated values of S-parameters. The complex permittivity and complex permeability of Teflon, Nylon and Delrin at the X-band frequencies are then determined

Nueva estructura convertidor de modos ancha banda TM01-a-TE11

A novel mode converter that transforms circular waveguide transverse magnetic (TM01) to transverse electric (TE11) circular waveguide is investigated, providing over 48% bandwidth of extraneous-mode-free operation at a conversion loss of less than 0.05dB. The design philosophy is based upon the unique use of two intermediate modes: coaxial TEM and a rectangular waveguide TE10, which provide input to output isolation of converter modes

Concepción de amplificadores de potencia microondas de alto rendimiento

In this paper, we present the design of a high efficiency class-F power amplifier in pHEMT technology using an accurate WREN/COBRA model at 2GHz. The transistor is overdriven into compression in order to maximize efficiency and output power. Three concepts of output matching networks are used in the design of class F power amplifiers, based on harmonics output terminations, that is shown to have a critical influence on PA performances when compared to a classical class B power amplifier (PAE= 61.56%, Pout=12.14 dBm). The design of the first amplifier is based on 2nd harmonic termination while all other harmonics are open circuited where the output is seen to consist of a half-wave rectified voltage waveform. 87.37% saturated PAE and 12 dBm output power are obtained for this amplifier. In the second amplifier, the 3th harmonic is terminated and the output is seen to consist of a square wave voltage waveform. This amplifier result in 72.87% saturated PAE and 12.52 dBm output power. Finally, following a detailed theoretical analysis, a class F matching network that suppress the necessary load harmonics, is used for the design of the third amplifier. The saturated PAE delivered is 74.19%, the output power is 12 dBm and a square wave voltage waveform is obtained at the output