When evaluating antennas, you must prioritize Frequency Range (MHz/GHz) to ensure compatibility with specific networks like 5G NR, 4G LTE, or IoT (LoRa/Sigfox). Key performance metrics include Gain (dBi), which determines signal strength and coverage distance, and Voltage Standing Wave Ratio (VSWR), which should ideally be less than 1.5 to minimize signal reflection and power loss. Additionally, verify the Polarization type (Vertical, Horizontal, or Cross-polarized) to match your system architecture.