Explanation: Antenna bandwidth describes the range of frequencies over which an antenna maintains acceptable electrical characteristics and efficiency. While an antenna is designed to be most efficient at a specific resonant frequency, it can still perform effectively across a *band* of frequencies around that point, typically defined by a maximum allowable Standing Wave Ratio (SWR) or a minimum radiation efficiency. Option A describes physical attributes, not the frequency range of operation. Option C defines the *beamwidth* of an antenna, which is a measure of its directivity, not its frequency performance range. Option D is not a recognized antenna parameter.