RFID Tag for Toll-Collection Systems Sergio Buenrostro Rocha 1 , Roberto Herrera Charles 1 , José Luis Medina Monroy 2 , Andrés Calvillo Téllez 1 1 Instituto Politécnico Nacional, Centro de Investigación y Desarrollo de Tecnología Digital, Tijuana, Baja California, Mexico sbuenrostro@citedi.mx, robcharles@citedi.mx, calvillo@citedi.mx 2 Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, B.C., Mexico jmedina@cicese.mx Abstract. The installation of an RFID tag on a vehicle's windshield for Automatic Vehicle Identification AVI applications has become a challenge for RFID users and service providers, since in some situations the tag is not read properly because some customers do not follow instructions of the recommended locations for installation. This problem is because each location of the windshield provides different distances to the car hood, car roof and A-pillars, and these metallic surfaces directly interact with the radiation resistance of the tag antenna and consequently change its performance (tag read range, frequency, radiation pattern, etc). There are locations in the windshield where the read range of the tag is severely reduced and in others it is greatly benefited. In the present work, an RFID tag for vehicle windshield with the Higgs 3 chip is developed. The tag is designed to operate at the 865 MHz – 868 MHz frequency band and it can be used in Europe, Asia and South Africa. It was observed that its read range is longer at any point of the windshield than that provided by the commercial RFID tag SMARTRAC DogBone with Monza 4 chip that has been well accepted internationally. In order to design the tag, the modeling of the antenna was performed by electromagnetic analysis using the method of moments, then it was prototyped and characterized directly in vehicles. It was also performed an analysis of the different locations of the windshield in order to find the best and worst locations to install the tag. Keywords: RFID, tag, toll. 1 Introduction In recent years, Radiofrequency Identification (RFID) systems have attracted much attention, particularly in the ultra-high frequency (UHF) band [1]. Radio Frequency Identification (RFID) is a wireless technology used for the identification and collection of data of objects, people or animals in digital form and automatically or manually. RFID is an alternative to bar code, but with superior capabilities since the readings are made using electromagnetic waves. A basic RFID system consists of a base station called reader or interrogator and a set of remote transponders called RFID tags. A basic interrogator consists of a reader antenna, a coaxial cable, RFID reader, network cable and a computer with dedicated software to manage the readings of the tags [2, 4, 8, and 55 ISSN 1870-4069 Research in Computing Science 148(2), 2019 pp. 55–62; rec. 2018-08-11; acc. 2019-09-27