Compact UWB Monopole Antenna for Automotive Communications

Abstract

This communication presents a bandwidth enhanced, compact, monopole antenna with modified ground plane for modern automotive ultra wide-band (UWB) applications. The proposed antenna has hybrid geometry and is constructed using half circular ring and half square ring. The ground plane of the fundamental radiator is curved and defected to improve the VSWR bandwidth. An extended ground stub is added to further enhance the bandwidth to suit the modern automotive requirements. The designed antenna covers 3.1 -10.9 GHz frequency spectrum with VSWR ≤ 2. This antenna can be conveniently placed inside the shark fin housing or it can be printed along with the existing Print Circuit Board (PCB) electronics nullifying the need for dedicated location for in-car communications. Furthermore, a simple 2 port Multiple Input Multiple Output (MIMO) antenna is constructed and its diversity performance is estimated. The prototype is fabricated and tested for impedance and radiation characteristics. Index Terms -UWB, printed antennas, wideband antennas, multi-service, automotive communications, MIMO I. INTRODUCTIONWING to the rapid development in wireless communication technologies, modern cars are fitted with multitude of information and communication systems. These systems are aimed at providing an enhanced service to the motorway users during mobility. The fast moving passenger devices undergo severe impairments in data rate and link quality due to multipath propagation and frequent cell handovers [1]. The severity is dictated by the speed of the vehicle and cell size. The conventional narrow-band systems may fail under such scenario since the performance of these communication systems is highly sensitive to transmitter and receiver locations [1]. Thus, to overcome the effects of mobility and achieve highest data rate, modern automobiles utilize UWB technology and MIMO/diversity techniques [2 -3]. The integration of MIMO/diversity with UWB further increases the robustness of the communication system.The UWB technology is also dedicated for in-car communications since the metallic body and the presence of passengers/load lead to complex propagation characteristics. The UWB technology is capable of handling these challenges for reliable functionality of the wireless systems [2]. Some of the potential applications of UWB include high speed mobile communications, in-car sensor network communication, automotive localization and tracking with high spatial resolution, emergency services and roadside assistance [1 -2].The antennas form the integral part of any communication system. In automobiles, the number of installed antenna increases with increase in the number of services offered by the vehicle which further increases while adopting MIMO/diversity techniques. Therefore, compact antennas operating over a large frequency spectrum receive special attention among automotive antenna designers.0018-926X (c)

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