Patch and panel antennas are directional antenna types that are commonly used by indoor Wi-Fi devices in a MIMO multiple spatial stream implementation. These antennas have a flat rectangular shape and can be mounted on walls or ceilings to provide coverage in a specific direction. They have a moderate gain and a relatively wide beamwidth, making them suitable for multipath environments where signals can reflect off different surfaces and create multiple spatial streams. Patch and panel antennas can also support polarization diversity, which means they can transmit and receive both horizontally and vertically polarized waves, increasing the MIMO performance. References: 1, Chapter 2, page 72; 2, Section 2.4