An antenna is a device designed to transmit or receive electromagnetic waves. Antennas are commonly used in communication systems, such as radio and television broadcasting, cellular phones, and wireless networks. They come in a variety of shapes and sizes, each with its own unique characteristics and advantages.

Antennas can be classified based on their frequency range, such as low-frequency (LF), high-frequency (HF), very high-frequency (VHF), ultra-high frequency (UHF), and microwave frequencies.
Wire antennas are the most common type of antenna and consist of a simple wire or a group of wires that are used to transmit or receive electromagnetic waves. They can be further classified into various types, such as dipole antennas, monopole antennas, loop antennas, and helical antennas.

Patch antennas are another popular type of antenna used in communication systems, particularly in wireless networks. They are compact, lightweight, and have a low profile, making them ideal for use in portable devices like cell phones and laptops.