I. Magrini

A new approach for concurrent Dual-Band IF Digital PreDistortion: System design and analysis

In this paper we propose a dual band digital predistorter (DB-DPD), suitable for concurrent dual-band power amplifiers. A sub-sampling receiver is at the basis of the feedback path, while the vectorial gain adjuster is achieved at the proper digital intermediate frequency. The proposed method adopts a conventional memory polynomial DPD for linearization. The approach is tested by system-level simulations and it was proven to be able to correct most of the nonlinearity, with only a modest performance loss with respect to single-band architectures.

A Distributed Sensor Network for Real-Time Acoustic Traffic Monitoring and Early Queue Detection

A novel sensor network configuration is introduced for traffic surveillance in Intelligent Transportation Systems. Distributed sensor nodes based on passive acoustic transducers are non intrusively/obtrusively deployed at motorway road-side to provide real-time traffic data collection for dynamic queue/jam detection. The system is capable to provide a complete real-time picture of traffic flow at unprecedented time/space scale. The infrastructure is based on a stand-alone, install-and-forget architecture, featuring an energy efficient protocol for sensor networking and providing connectivity to back-end computing environment via TCP/IP over UMTS. Extensive experimental demonstration is given for long term operation on a motorway test site.

A design method for single-feed wideband microstrip patch antenna for switchable circular polarization

In this paper a design method for a circular polarized small-size microstrip antenna on a short dielectric layer is presented. Its known that exciting two detuned modes with a single coaxial probe makes possible circular polarization (CP) but as yet little efforts were made in order to control CP frequency and exact 50 ohm matching. A straight forward circuital model for the device can solve both this issues and gives hint for the best radiator design; our prototype is a circular disc slotted by a concentric elliptical cut in order to slightly perturb the central symmetry and obtain the modal degeneration. It includes a SPDT to allow the switching between the two CP. The prototype is designed for 2.44 GHz and exhibits a return loss of 19 dB, an impedance BW of 120 MHz a directivity of 6 dB and an estimated gain of 1.8 dB.

A real-time traffic monitoring based on wireless sensor network technologies

Non intrusive systems-based traffic monitoring, is a paradigm for Intelligent Transportation Systems (ITS). Real time systems capable of providing prompt information, like loop detectors, laser/radar systems and video cameras, were proposed in the past but they are affected by some straits in deployment. In this paper a Traffic Monitoring Wireless Sensor Network system (TM-WSN), based on acoustic arrays and powered by effective post-processing, is proposed. The system is composed by an hierarchical scheme of Master Nodes and Sensor Nodes linked with a multi-hop protocol. Key features are traffic monitoring and queue detection to be performed in real-time at unprecedented space scale.

A 2.45 GHz smart antenna for location-aware single-anchor indoor applications

This paper proposes a new switched beam array optimized for 2.45 GHz wireless indoor applications. The antenna supports directional communication to enable spatial reusability, and polarization diversity to mitigate multipath propagation. It also supports absolute 2D target localization using measurements from a single anchor node. The paper describes the antenna design, the implementation and the experimental characterization, along with its positioning applications. The localization results obtained with data collected from indoor measurements, showing an average localization error as low as 1.7 m.

Full-Spectrum Behavioral Model for Linearized Sub-Harmonic Mixer Extracted by Large-Signal Vectorial Measurements

A behavioral model for microwave mixers operating in linear regime, which is extracted from large-signal vectorial measurement, is introduced herein. This is capable of predicting the performance of the converted signals and the main mixing products as well as the LO leakage at both the two signal ports. The mixer performance is provided as a function of a set of a priori defined LO levels and predicts the response with respect to an arbitrary LO phase. This paper gives a detailed analytical treatment of the model and its experimental validation by using a hybrid technology sub-harmonic mixer operating at IF=650 MHz and RF=5.2 GHz

Compact Concurrent Dual-Band Power Amplifier for 1.9GHz WCDMA and 3.5GHz OFDM Wireless Systems

The aim of this paper is to focus on the dual band power amplifier design and characterization as an enabling technology for beyond 3G wireless systems. The design approach within a full characterization of the dual band power amplifier is given in the paper. For 1.98 GHz 3 GPP UL WCDMA and 3.42 GHz 5 MHz 16QAM WiMAX digital systems, the dual-band concurrent exhibited simultaneous peak power levels of 24 dBm and 17 dBm respectively, to maintain ACPR and EVM within the regulatory requirements. A performance discussion is then outlined with respect to multi band multi module PA architectures for software defined radio wireless transmitters.

A 2.14 GHz GaN power amplifier with 1-bit discrete power control

This paper focuses a GaN HEMT power amplifier with 1-bit power control and provides experimental data. It relies on a new concept of power combining allowed by an adaptive gate bias control scheme. At 2.1 GHz CW the discrete power control technique enables a linear factor 3.3 efficiency enhancement at the maximum power back-off of 7 dB, while a maximum output power of 34 dBm and a peak drain efficiency of 35%.

Concurrent dual-band SiGe HBT power amplifier for wireless applications

This paper presents an investigation of a concurrent low-cost dual-band power amplifier (PA) fabricated in SiGe technology, able to simultaneously operate at two frequencies of 2.45 and 3.5-GHz, including an evaluation of its system level performance potentiality. Taking into account the technology novelty and the lack of device characterization and modeling, a hybrid (MIC) approach has been adopted both for a fast prototyping of the PA and for the evaluation of the device potentiality based on an extensive linear and nonlinear characterization. The comparison of PA performance in single-band or concurrent mode operation will be presented. In particular, the measured PA prototype shows an output power of 17.2 and 17-dBm at a 1-dB compression point, at 2.45 and 3.5-GHz, respectively, for CW single-mode operation, with a power added efficiency around 20%. System-level analysis predicts that, when the PA is operated under the 20-MHz Orthogonal Frequency-Division Multiplexing (OFDM) concurrent signals, the maximum output power levels to maintain the Error Vector Magnitude (EVM) within 5% are 11 and 3.5-dBm at 2.45 and 3.5-GHz, respectively. Moreover, new concepts and possible new system architectures for the development of the next generation of the multi-band transceiver front-end will be provided with an extensive system-level evaluation of the amplifier.

A Balanced Sub-Harmonic Mixer for multi-OFDM Ultra Wide Band Direct Conversion Transmitters

In this paper a single balanced sub-harmonic mixer, suitable for direct-conversion IEEE 802.15.3a ultra wide band transmitter, is introduced, fabricated and tested. The circuit, which consists of two pairs of anti-parallel diodes connected by a wideband balun and proper frequency terminations, is optimized for direct up-conversion in the 3.1-4.8 GHz band. The prototype was realized by means of hybrid technology, surface mount packaged Schottky diodes and passive components. The measurements highlight a conversion loss ranging from 12 dB to 15 dB and an in-band second LO harmonics in the range of 48 dB to 57 dB. The proposed passive mixer optimum functionality is achieved with a LO power of 7 dBm. Finally, the prototype response was shaped by a microstrip multisections coupled-lines band pass filter, designed to operate as output spectrum shaping. The system level considerations demonstrated the suitability of the proposed circuit topology for UWB MBOA applications