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- Non-uniform microstrip antenna array for RX DSRC communicationsPublication . Varum, Tiago; Matos, João N.; Abreu, Ricardo; Pinho, PedroThe 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. © 2014 IEEE.
- Nonuniform broadband circularly polarized antenna array for vehicular communicationsPublication . Varum, Tiago; Matos, João N.; Pinho, Pedro; Abreu, RicardoRoad 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 onbo ard 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 impact of different power dividers used in a non-uniform planar antenna arrayPublication . Varum, Tiago; Matos, João N.; Abreu, Ricardo; Pinho, PedroWireless 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. © 2014 IEEE.
- Non-uniform microstrip antenna array for DSRC in single-lane structuresPublication . Varum, Tiago; Matos, João N.; Pinho, PedroVehicular communications have been subject to a great development in recent years, with multiple applications, such as electronic payments, improving the convenience and comfort of drivers. Its communication network is supported by dedicated short range communications (DSRC), a system composed of onboard units (OBU) and roadside units (RSU). A recently conceived different set-up for the tolling infrastructures consists of placing them in highway access roads, allowing a number of benefits over common gateway infrastructures, divided into several lanes and using complex systems. This paper presents an antenna array whose characteristics are according to the DSRC standards. Additionally, the array holds an innovative radiation pattern adjusted to the new approach requirements, with an almost uniform wide beamwidth along the road width, negligible side lobes, and operating in a significant bandwidth.
- Detect and pointing algorithm’s performance for a planar smart antenna array: a reviewPublication . Varum, Tiago; Matos, João N.; Pinho, PedroAn adaptive antenna array combines the signal of each element, using some constraints to produce the radiation pattern of the antenna, while maximizing the performance of the system. Direction of arrival (DOA) algorithms are applied to determine the directions of impinging signals, whereas beamforming techniques are employed to determine the appropriate weights for the array elements, to create the desired pattern. In this paper, a detailed analysis of both categories of algorithms is made, when a planar antenna array is used. Several simulation results show that it is possible to point an antenna array in a desired direction based on the DOA estimation and on the beamforming algorithms. A comparison of the performance in terms of runtime and accuracy of the used algorithms is made. These characteristics are dependent on the SNR of the incoming signal.
- Non-uniform microstrip antenna array for DSRC in single-lane structuresPublication . Varum, Tiago; Matos, João N.; Pinho, PedroVehicular communications have been subject to a great development in recent years, with multiple applications, such as electronic payments, improving the convenience and comfort of drivers. Its communication network is supported by dedicated short range communications (DSRC), a system composed of onboard units (OBU) and roadside units (RSU). A recently conceived different set-up for the tolling infrastructures consists of placing them in highway access roads, allowing a number of benefits over common gateway infrastructures, divided into several lanes and using complex systems. This paper presents an antenna array whose characteristics are according to the DSRC standards. Additionally, the array holds an innovative radiation pattern adjusted to the new approach requirements, with an almost uniform wide beamwidth along the road width, negligible side lobes, and operating in a significant bandwidth.
- Printed nonuniform antenna array for WI-FI sectorized communicationsPublication . Varum, Tiago; Matos, João N.; Pinho, PedroWireless networks have joined to the sports venues, offering to the public a set of facilities, such as the access to email, news, and also to use the social networking, uploading their photos. New challenges have emerged to provide Wi-Fi in this densely populated stadiums, such as increasing capacity and coverage. In this article, an access point antenna array to cover a sector of a stadium is presented. Its structure, designed in a low cost material allows to reduce the total manufacturing costs, an important factor due to the large number of antennas required in these venues. The material characteristic, the broad bandwidth of operation (300 MHz), along with to the low side lobe levels, important to reduce interference between sectors, makes this antenna well-positioned for wireless communications in these particular locals. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2037-2041, 2015.
- Circularly polarized microstrip antenna array for the Ka-bandPublication . Varum, Tiago; Matos, Joao; Duarte, Vanessa; Pinho, PedroThe growing needs of higher transmission rates lead to the use of the Ka frequency bands and multi-beam technology, in the satellite communications, allowing more coverage. This fact leads to the need for the use of directive antennas and beamforming techniques to achieve a precise control of radiation pattern. This paper presents the design of a circularly polarized microstrip antenna array, at 29 GHz, suitable to satellite communications. The array will be a module part to develop an ample antenna array suitable to fulfill the satellite requirements, and feed with an electronic beamforming network.
- Detect and pointing algorithm's performance for a planar smart antenna array: a reviewPublication . Varum, Tiago; Matos, João N.; Pinho, PedroAn adaptive antenna array combines the signal of each element, using some constraints to produce the radiation pattern of the antenna, while maximizing the performance of the system. Direction of arrival (DOA) algorithms are applied to determine the directions of impinging signals, whereas beamforming techniques are employed to determine the appropriate weights for the array elements, to create the desired pattern. In this paper, a detailed analysis of both categories of algorithms is made, when a planar antenna array is used. Several simulation results show that it is possible to point an antenna array in a desired direction based on the DOA estimation and on the beamforming algorithms. A comparison of the performance in terms of runtime and accuracy of the used algorithms is made. These characteristics are dependent on the SNR of the incoming signal.
- Non-uniform microstrip antenna array for tolling using a single access lanePublication . Varum, Tiago; Matos, Joao; Pinho, PedroOver the last few years we have seen the progress of vehicular communications, as a way of development of the entire highway infrastructure, offering a set of new applications and functionalities to the users. The electronic collection for parking, tolls, gas stations, are some outcome of this technological development. This paper presents an antenna array according with the dedicated short range communications standards that rules the tolling applications, with the specific application in the access roads to highways. The radiation pattern with an innovative shape, combined with good wide operating band opens good perspectives for the application of this antenna in vehicular communications.