This document discusses different aspects of antennas used in wireless networks and protocols. It begins by defining an antenna as an array of conductors electrically connected to transmit and receive radio waves. It then discusses key antenna parameters including radiation pattern, efficiency, gain, and bandwidth. Radiation pattern describes the direction of radiated power. Efficiency is the ratio of radiated to input power. Gain indicates how directional antennas concentrate power in specific directions compared to an isotropic antenna. Bandwidth refers to the range of frequencies an antenna can transmit or receive effectively. The document provides examples of omnidirectional and directional antennas and explores these antenna parameters in more detail.