Ricardo Abreu

Nonuniform Broadband Circularly Polarized Antenna Array for Vehicular Communications

Road safety applications drive the development of vehicular communications as support to intelligent transport systems. The communications network necessary for this is supported by dedicated short-range communications (DSRC), which is based on roadside units (RSUs) and onboard units. In the RSU, the DSRC physical-layer standards, along with practical issues, require specific radiation patterns of the respective antenna, leading to the use of unusual arrays of antennas. This paper describes a new concept based on a binomial array structure, which simplifies the design of the antenna array while ensuring good performance. The new structure developed for this antenna enabled the design of a feed network using unbalanced power dividers in the same plane as that of the radiating elements, maintaining the favorable characteristics of microstrip antennas. The array thus obtained met the desired specification, in terms of a radiation pattern with a bandwidth greater than 1 GHz.

Low cost transceiver for DSRC applications

In this paper a low cost transceiver for DSRC applications is presented. First a brief overview of the new European Standards is given followed by a possible implementation of a on board unit (OBU). The implementation proposed for the RF part can be implemented with very low cost components, making this solution viable for the huge DSRC market.

Non-uniform microstrip antenna array for Rx DSRC communications

The urgent need to mitigate traffic problems such as accidents, road hazards, pollution and traffic jam have strongly driven the development of vehicular communications. DSRC (Dedicated Short Range Communications) is the technology of choice in vehicular communications, enabling real time information exchange among vehicles V2V (Vehicle-to-Vehicle) and between vehicles and infrastructure V2I (Vehicle-Infrastructure). This paper presents a receiving antenna for a single lane DSRC control unit. The antenna is a non-uniform array with five microstrip patches. The obtained beam width, bandwidth and circular polarization quality, among other characteristics, are compatible with the DSRC standards, making this antenna suitable for this application.

A Homodyne Low Cost Uplink Receiver for Digital Short Range Communication Systems

In this paper we propose an architecture for a homodyne receiver for dedicated short range communications (DSRQ for road traffic and transport telematics (RTTT). The receiver was thought with the new European standard EN12253 in mind, although its architecture may be adopted in other scenarios.

The impact of different power dividers used in a non-uniform planar antenna array

Wireless communications are widely used for various applications, requiring antennas with different features. Often, to achieve the desired radiation pattern, is necessary to employ antenna arrays, using non-uniform excitation on its elements. Power dividers can be used and the best known are the T-junction and the Wilkinson power divider, whose main advantage is the isolation between output ports. In this paper the impact of this isolation on the overall performance of a circularly polarized planar antenna array using non-uniform excitation is investigated. Results show a huge decrease of the array bandwidths either in terms of return loss or in polarization, without resistors.

Microstrip antenna for vehicular communications with improved axial ratio band

The use of microstrip antennas has grown in wireless communications in last few years. Due to their characteristics, simplicity and low cost of production, they allow the development of high quality and high efficiency antennas in diverse applications. The dedicated short range communications (DSRC) widely used in vehicular communications is one of the possible uses. In this paper, it is described the design of an antenna with characteristics according to the European standard for DSRC communications, and its radiation pattern is suited to road communications. Moreover, the antenna has the advantage of a wide frequency band where good circular polarization characteristics are shown.