Bujalance, A.; Picher, C.; Anguera, J.; Andújar-Linares, A.; Puente, C. Microwave and optical technology letters Vol. 55, num. 8, p. 1770-1779 DOI: 10.1002/mop.27709 Data de publicació: 2013-08 Article en revista
Picher, C.; Anguera, J.; Bujalance, A.; Andújar-Linares, A.; Puente, C. Microwave and optical technology letters Vol. 55, num. 1, p. 173-180 DOI: 10.1002/mop.27232 Data de publicació: 2013-01-01 Article en revista
The ground plane of a handset device plays an important
role in the radiation process. As a consequence, through a ground plane modification, it is possible to obtain a multiband performance while keeping small antenna dimensions. Numerical simulation using Method of Moments has been used to understand the effect of the slots and a prototype has been built to validate the solution. The proposal consists in a multiband planar monopole handset antenna featuring a small area of 13 mm 11 mm with a slotted ground plane operating in multiple communication standards (GSM850, GSM900, DCS, PCS, UMTS, LTE2300, WiMAX, Bluetooth, and Wi-Fi). Thanks to the presence of the slots, the bandwidth and efficiency results have been significantly improved.
The ground plane of a handset device plays an important role in the radiation process. As a consequence, through a ground plane
modification, it is possible to obtain a multiband performance while
keeping small antenna dimensions. Numerical simulation using Method
of Moments has been used to understand the effect of the slots and a
prototype has been built to validate the solution. The proposal consists
in a multiband planar monopole handset antenna featuring a small area
of 13 mm x 11 mm with a slotted ground plane operating in multiple
communication standards (GSM850, GSM900, DCS, PCS, UMTS,
LTE2300, WiMAX, Bluetooth, and Wi-Fi). Thanks to the presence of the
slots, the bandwidth and efficiency results have been significantly
There is a need of developing new techniques for enhancing the bandwidth of handset antennas without increasing the antenna volume in order to incorporate more frequency bands into the cell phones. The technique to enhance the bandwidth proposed herein consists in adding a conductive strip connected to the ground plane at the opposite edge of the handset antenna location. Conductive strip tunes the ground plane mode to effectively improve the bandwidth at the low frequency region (∼900 MHz) while keeping the same antenna volume. An electrical model is used to give an insight into the behavior concluding that the conductive strip is a useful mechanism to improve the bandwidth. The model demonstrates that the length of the conductive strip can be reduced by inductive or dielectric loading, as well as by reducing its height. Simulations and measurements show how the conductive strip excites the resonance of the ground plane mode improving the bandwidth and validating the electrical model predictions. The proposed technique is applied to a dual-band (900–1800 MHz) planar inverted F-antenna providing a measured bandwidth enhancement of 1.6 times when using the strip at the low frequency region while keeping the same performance at the high frequency region (∼1800 MHz).
The feasibility of optical amplification solutions for extended reach next generation access networks in C + L bands is studied. Amplification schemes based on Raman fiber amplifier and their combination with remotely pumped erbium-doped fiber amplifiers are assessed and optimized. The results concerning a ring with 80 km for rural scenario demonstrate gain equalization over a bandwidth of 50 nm. The survey was complemented with experimental results
Molina, M.; Gómez, D.; Aragones, X.; Mateo, D.; Gonzalez, J. Microwave and optical technology letters Vol. 53, num. 7, p. 1632-1637 DOI: 10.1002/mop.26043 Data de publicació: 2011-07 Article en revista
This work presents the design procedure followed to obtain a low-power voltage-controlled oscillator (VCO) robust against
high-frequency substrate noise, using as a demonstrator a 2.5 GHz VCO with quadrature outputs (QVCO) based on a 5-GHz LC tank resonant VCO (LC-VCO) and frequency divider. A simple, intuitive, and easy to handle analytical model is proposed to identify the design parameters that contribute to the performance degradation of LC-VCOs due to the
effect of high frequency substrate noise. The guidelines obtained have been applied in the design of the low-power QVCO. Finally, the work discusses several trade-offs that can be used to maximize the immunity of a LC-VCO against substrate noise.
Teixeira, A.; Costa, L.; Wada, N.; Chanclou, P.; Forin, D.; Prat, J.; Tosi Beleffi, G. Microwave and optical technology letters Vol. 52, num. 10, p. 2378-2380 DOI: 10.1002/mop.25438 Data de publicació: 2010-10 Article en revista
Rodríguez, P.; Ribó, M.; Pajares, F.; Sanchez, A.M.; Regué, J.; Pérez, A.; Pradell, L. Microwave and optical technology letters Vol. 52, num. 6, p. 1328-1331 DOI: 10.1002/mop.25161 Data de publicació: 2010-03-19 Article en revista
Risco, S.; Anguera, J.; Pérez, A.; Andújar-Linares, A.; Puente, C. Microwave and optical technology letters Vol. 52, num. 2, p. 359-364 DOI: 10.1002/mop.24893 Data de publicació: 2010-02 Article en revista
Girbau, D.; Lázaro, A.; Martínez, E.; Masone, D.; Pradell, L. Microwave and optical technology letters Vol. 51, num. 9, p. 2025-2028 DOI: 10.1002/mop.24550 Data de publicació: 2009-06 Article en revista
A simple human body phantom model is proposed and
used to demonstrate that the radiation efficiency of an internal handset
antenna operating at the FM band can be improved for a particular
holding position up to 10 dB. To corroborate the numerical results, an
experiment using a real human body has been performed showing very
A passive internal handset antenna for FM reception is presented
using electromagnetic simulations as well as laboratory experiments.
Received signal for the antennas have been demodulated and the quality of the
audio signal evaluated. Results have been compared with a long antenna ( /4)
confirming that the proposed solution is a good candidate to migrate to a full
wireless FM system that may be integrated into a handset phone.
This article presents an electrothermally-actuated lateral resistive-contact RF-MEMS parallel switch for application to low GHz wireless communication bands. The device is driven by a metal electrothermal actuator, which achieves large displacements and contact forces at much lower temperatures than conventional polysilicon electrothermal actuators. It was manufactured on a standard low-resistivity substrate and its RF performance was improved by suspending the structures 25 µm from the substrate. Measured (at 1 GHz) insertion loss is -0.11 dB, return loss -41 dB, and isolation -22 dB.
A compact antenna gain measurement system suitable for
wireless devices is presented. The method needs the antenna under test,
a planar electric conductor, and a vector analyzer. It is possible to obtain
the total gain by a reflection measurement. Several simulations
show a guideline to optimize the set-up. Finally, some wireless devices
operating at GSM900, GSM1900, and Bluetooth® are tested and compared
with gain obtained by a three radiation pattern method.
In this work, a nonlinear model to predict actuation characteristics in lateral electrostatically-actuated DC-contact MEMS switches is proposed. In this case a parallel-plate approximation cannot be applied. The model is based on the equilibrium equation for an elastic beam. It is demonstrated that the contribution of fringing fields is essential. The model relies on finite-difference discretization of the structures, applying boundary conditions and is solved with a Gauss-Seidel relaxation iteration scheme. Its usefulness is demonstrated in a series MEMS switch with lateral interdigital electrostatic actuation.
A method to extract the elements of the small-signal equivalent circuit and the noise parameters (NPs) of heterojunction bipolar transistors (HBTs) is presented. The extraction is done by simultaneous fitting of the measured S-parameters, noise figure (for a well-matched impedance), and NPs (estimated using the so-called F50 method). An additional error term, given by the root square sum of the differences between the NPs estimated from the F50 method and the NPs directly computed using the Hawkins model, is considered in order to avoid nonphysical results in the extraction of the intrinsic noise sources. To obtain the initial values of the equivalent-circuit elements, analytical expressions are applied under a number of bias conditions, namely, reverse bias, forward bias, and active bias. Experimental verification of the extraction of the equivalent-circuit elements and NPs of an HBT, up to 8 GHz, are presented, and the NPs are compared to those measured with an independent (tuner-based) method. The behavior of Fmin, extracted using the proposed method, as a function of the HBT collector current, is also presented.
This paper presents a study of the nonlinear effects introduced by MEMS varactors when excited with digitally modulated RF signals (QPSK and 16 QAM). The study is based on simulating a nonlinear model of the MEMS device using harmonic-balance and envelope solvers, and on experimental measurements of the wave reflected by the on-wafer MEMS device. It is shown that the adjacent-channel power ratio (ACPR) and error-vector magnitude (EVM) of the digital signal suffer a degradation due to the device nonlinear distortion.
Bonache , J.; Martín, F.; Garcia-Garcia, J.; Gil, I.; Marqués Sillero, Ricardo; Sorolla, M. Microwave and optical technology letters Vol. 46, num. 3, p. 283-286 Data de publicació: 2005-08 Article en revista
Bonache , J.; Martín, F.; Falcone, G.; Garcia-Garcia, J.; Gil, I.; Lopetegi, T.; Laso, M.; Marqués, R.; Medina, F.; Sorolla, M. Microwave and optical technology letters Vol. 46, num. 1, p. 33-35 Data de publicació: 2005-07 Article en revista
Garcia-Garcia, J.; Bonache , J.; Gil, I.; Martín, F.; Marqués, R.; Falcone, F.; Lopetegi, T.; Laso, M.; Sorolla, M. Microwave and optical technology letters Vol. 44, num. 4, p. 376-379 Data de publicació: 2005-02 Article en revista
A new method for the determination of a distributed FET noise model is presented. It is based on the extraction of the intrinsic noise-correlation matrix of an elemental section of the device from the device's noise figure, measured for only one source-impedance state at a number of frequency points. Experimental results up to 40 GHz are given.
This paper presents a broadband-noise circuit model for a cold-FET (Vds = 0 V) with a reverse-biased gate. The noise model includes two intrinsic uncorrelated noise-current sources whose spectral densities are determined from measurement of the device's S parameters and noise powers. The model is used to characterize the device's excess noise ratio (ENR) for application to full receiver-noise calibration. Experimental results up to 40 GHz are given.
This paper presents a method for characterizing coplanar waveguide-to-microstrip (CPW-M) transitions by using on-wafer coplanar (CPW) microprobes. It is based on extracting the transmission matrix of the CPW-M transition from the measurement of the S parameters of two microstrip transmission lines of different lengths, each of which includes two CPW-M transitions. To verify the proposed method, the S parameters of a zero-length line, which is composed of two CPW-M transitions (thru connection) and has not been used in the transition characterization, are measured up to 40 GHz and are compared to those extracted and obtained from electromagnetic simulations. The method is applied to the measurement of a microstrip coupled-line filter embedded in CPW-M transitions.
The bias-dependence of microwave-FET intrinsic noise sources in their hybrid configuration is theoretically determined, using a new quasi-2D (Q-2D) physical model based on Thornber's current equation . It is shown that the correlation coefficient cannot be neglected, in agreement with empirical work in the literature. Experimental verification using noise-parameter measurements up to 26 GHz is presented.
This paper presents a method to characterize the excess noise ratio (ENR) of an unmatched avalanche noise diode for application as an on-wafer noise source. It is based on the determination of a broadband device noise circuit-model from its measured reflection coefficient and noise powers. Measured ENR is used to calibrated a noise receiver up to 40 GHz.
Anguera, J.; Montesinos, G.; Puente, C.; Borja, C.; Soler, J. Microwave and optical technology letters Vol. 2, num. 37, p. 100-103 DOI: 10.1002/mop.10836 Data de publicació: 2003-04-20 Article en revista
This work describes the application of a commercial
CAD software to implement load-pull techniques in the design of microwave
mixers. This method is used to generate conversion-loss regions
when a diode is pumped and operated as a mixer circuit. Emphasis is
placed on the inclusion of image and out-of-band terminations to optimize
the operating conditions required to obtain low conversion loss. An
X-band 5-dB conversion-loss mixer is designed and tested using this