A single-layer pentaband antenna with very small frequency ratio for urban vehicular communication application has been presented. The proposed antenna is linearly polarized and is designed to cover the navigation and communication frequencies. This antenna utilizes a square patch radiator loaded with an inverted U-slot and a coupled C-slot to provide resonance at the navigation frequencies-viz., 1.176, 1.381, and 1.575 GHz-and communication frequencies-viz., Satellite Radio Broadcast Service (SRBS) at 1.472 GHz and Mobile services at 1.675 GHz. The designed antenna exhibits the lowest frequency ratio of 1:1.17:1. 25:1.35:1.43 with nonoverlapping frequency bands. Furthermore, a parametric study has been carried out to investigate the effect caused by the change in slot parameters in the antenna aperture. Both theoretical and experimental results have been presented and discussed.