An Omnidirectional Multiband Antenna for Railway Application

In this letter, we propose a top-mounted train antenna to work for GSM, LTE, and Wi-Fi communication systems. The antenna has a double-sided planar dipole configuration with a single port. An additional feeding structure has also been designed. To achieve multiband, an asymmetrically folded branch was loaded, whereas slits were etched on the rectangular patch. The structure was then optimized considering the roof and coupling effects. Simulated results show that the antenna can operate in the bands of 825-960 MHz, 1.7-2.7 GHz, and 5.7-5.9 GHz with a return loss better than 10 dB. The dimensions of the antenna are 116 mm × 40 mm × 1.6 mm. A gain of 4.27-9.82 dBi with omnidirectional (horizontal) coverage is realized to ensure reliable mobile communication. The antenna can be integrated with a global navigation satellite system (GNSS) antenna in a compact radome. It has the advantages of low cost and easy fabrication. Good agreements are observed between measured and simulated results. Furthermore, the proposed dipole is compared with a commercial antenna for similar applications in terms of impedance matching, isolation, and radiation characteristics.