What Is a Patch Antenna?

A patch antenna is a pie-shaped directional antenna, which is composed of two metal plates (one of which is larger than the other) with a sheet-shaped dielectric in the middle. And other access points cannot be placed in a central indoor location. The patch antenna produces hemispherical coverage, which propagates from the mounting point, with a propagation range between 30 and 180 degrees.

Because the feeding network of dual-frequency patch antennas is relatively complicated, especially in the array, it has been paid little attention to for a long time. With the rapid development of modern communications, dual-band patch antennas have attracted increasing interest. In addition to the advantages in weight, space and cost, the dual-band patch antenna can ensure the separation and matching of the transmit and receive channels. It has various forms in structure, and can be summarized in principle as: orthogonal mode dual frequency-dual polarized patch antenna (single layer structure), multi patch dual frequency antenna, reactance-loaded dual frequency patch antenna and small array Dual frequency antenna.

Microstrip antennas are divided into three categories: microstrip patch antennas, microstrip antennas, and microstrip traveling wave antennas. Here, the microstrip patch antenna refers to a resonant microstrip patch antenna. The biggest feature of this antenna is high efficiency, but the impedance band is narrow.

Microstrip patch antennas have been widely used for their relatively high efficiency and mature analysis methods. However, the narrow bandwidth of such antennas has limited their application fields. In addition to military applications, microstrip patch antennas can also be used in mobile communication systems, satellite communication systems, global positioning systems, and remote sensing systems. If applied to mobile communication systems, it can be used as a mobile phone antenna and mobile phone body, thus solving the problems of low power of the whip antenna, not easy to carry and the influence of electromagnetic radiation on the human brain. ^[2]

The narrow-band characteristics of a microstrip patch antenna are determined by its high-Q resonant nature. This means that matching is achieved at resonance and that the reactance component changes sharply to mismatch when the frequency deviates from resonance. Therefore, the method of widening the frequency band can be explored by reducing various aspects of the Q value, and it can also be considered to use additional matching measures to achieve. Commonly used methods are thick substrates, substrates with smaller X _r or larger tanW (lossy), additional impedance matching networks, multi-layer structures, windowing on the patch or ground plate, non-linear substrate materials, Non-linear adjustment elements, wedge-shaped or stepped substrates, etc. ^[2]