It is possible to determine the width of the patch, w, using Equation 1. This article will focus on the cavity model approximation in most situations and will fall back on the transmission line model to derive parameters such as the input impedance of the patch. It is possible to derive the parameters of patch antenna using a few different techniques. The second is the feed line.įinally, the third part is the ground plane. The inset patch design has three distinct geometrical regions. This means that it is not possible to make an inset patch radiate with circular polarization without using four feeds. This creates a skew in the pattern, causing the boresight of the antenna not being located exactly normal to the planar surface of the patch antenna. The patch antenna radiates from the side in which it is fed and the opposite side. The areas where the patch radiates from are shown below. The Microstrip patch antenna is a little different than many antennas, as the structure itself does not radiate, but rather the edge gaps between the patch and the ground plane. Through varying the location of where the microstrip connects to the patch antenna the measured input impedance can be controlled. There are many different ways to feed a patch antenna, the inset fed patch antenna is fed via a microstrip feed line connected to a specific point within the patch. This type of antenna is inherently a high Q antenna, meaning that this antenna is relatively narrow banded. If the feed is located closer to the edge of the patch the input impedance will be high, if the feed is located closer to the center of the patch the impedance will be low.īelow is the standard input impedance of an inset fed patch antenna at 2. The natural input impedance of a patch antenna dependent on where within the patch the feed is located. If the antenna is loaded with different dielectrics, the length of the antenna decreases as the dielectric constant increases. Note that the wavelength depends on the material situated between the ground plane and the patch meaning when air is between the patch and ground, the length of the rectangle electric conductor is of the free-space wavelength. The rectangular piece of copper measures long. This antenna is designed using a rectangular piece of electric conductor situated above a ground plane. The rectangular patch is one of the more common types of patch antennas. A well designed patch antenna can have a peak gain between 6 and 8dBi, and as such it is considered to have a directional pattern click to rotate 3D image below which is linearly polarized along the width of the patch. All the equations for determining the size and impedance of an inset fed patch antenna are at the end of this post. There are many different types of microstrip patch antennas, and many of them can be found in the MicrowaveTools Antenna A-Z database.

Microstrip patch calculator