Patch antenna

Lore & Background

The patch antenna was the original type of microstrip antenna described by Howell in 1972. Its radiation mechanism arises from fringing fields along the radiating edges of the patch. These fringing fields cause the antenna to behave electrically larger than its physical dimensions, so a resonant patch uses a length slightly shorter than one-half wavelength at the operating frequency. The antenna is mainly practical at microwave frequencies, where wavelengths are short enough that the patches are conveniently small. A variant commonly used in mobile phones is the shorted patch antenna, or planar inverted-F antenna (PIFA), in which one corner or edge of the patch is connected to ground via a pin, providing better impedance matching than the standard patch.

Reader's Guide

The patch antenna is widely used in portable wireless devices because it can be easily fabricated on printed circuit boards. Its low profile and planar structure make it suitable for integration into compact electronics. Multiple patch antennas on the same substrate can be combined to form high-gain array antennas and phased arrays, where the beam can be electronically steered. This capability is exploited in applications such as space probe instruments, for example the Microwave Radiometer on the Juno spacecraft, which uses patch array antennas. The shorted patch variant (PIFA) is particularly common in mobile phones due to its improved matching characteristics. Overall, the patch antenna's simplicity, ease of manufacturing, and adaptability to arrays have made it a fundamental antenna type for modern wireless communication systems.

Did You Know?

• The two metal sheets form a resonant microstrip transmission line with a length of approximately one-half wavelength.
• A variant called the shorted patch antenna (PIFA) has one corner or edge connected to ground via a pin for better matching.
• Multiple patch antennas on the same substrate can be used to make high-gain array antennas and phased arrays.