Microstrip antennas, also called patch antennas, are very popular antennas in the microwave frequency range because of their simplicity and compatibility with circuit board technology. The rectangular patch antenna is one of the most commonly used microstrip antennas. Edge-fed microstrip antennas are suited to direct integration with microstrip circuits, since the antenna can be etched on the same substrate. When sharing a substrate with microstrip circuits, the antenna performance is, however, limited by the conflicting substrate requirements for antenna and circuit use. This antenna is popular as an array-element, but for large arrays the feed-network radiation may affect performance considerably.