When selecting a mobile antenna, you must ensure it covers the specific bands required for your region, typically 136-174MHz for VHF and 400-470MHz for UHF. For urban environments with many obstacles, a high-gain antenna (e.g., 3.0dB to 5.5dB) is preferable to maintain signal strength. However, for mountainous terrain, a lower gain antenna may actually perform better due to a wider radiation pattern. Always verify that the VSWR (Voltage Standing Wave Ratio) is less than 1.5 to prevent damage to the radio transmitter.