The antenna is a device that radiates radio frequency signals from the transmission line into the air or receives it from the air to the transmission line. It can also be regarded as an impedance converter or an energy converter. Transform into electromagnetic waves propagating in an unbounded medium, or vice versa. For the design of a wireless transceiver device used in a radio frequency system, the design and selection of the antenna is an important part of it. A good antenna system can achieve the best communication distance. The size of the same type of antenna is proportional to the wavelength of the radio frequency signal. The lower the frequency, the larger the antenna required.
Antennas can be divided into external antennas and built-in antennas according to the installation position. Those installed inside the device are called built-in antennas, and those installed outside the device are called external antennas. For small-sized products such as handheld devices, wearable designs, and smart homes, built-in antennas are commonly used, with high integration and beautiful appearance. The Internet of Things and smart hardware products need to transmit data online, so they all need to use antennas.
The smaller the space and the more frequency bands, the more complex the antenna design. External antennas are generally standard products. You can use the antennas in the required frequency bands without debugging, just plug and play. For example, express cabinets, vending machines, etc., generally use magnetic external antennas, which can be sucked on the iron shell. These antennas cannot be placed in the iron cabinet, and the metal will shield the antenna signal, so they can only be placed outside. This article focuses on the classification and selection method of the antenna, and introduces the relevant information of the antenna.
1. External Antenna
External antennas can be divided into omnidirectional antennas and directional antennas according to the different radiation angles of the radiation field.
Omnidirectional antennas, that is, 360° uniform radiation on the horizontal pattern, that is, the so-called non-directional, and a beam with a certain width on the vertical pattern. In general, the smaller the lobe width, The bigger the gain.
A directional antenna refers to an antenna that transmits and receives electromagnetic waves in one or several specific directions with particularly strong, while transmitting and receiving electromagnetic waves in other directions is zero or extremely small. The purpose of using a directional transmitting antenna is to increase the effective utilization of radiated power and increase the confidentiality; the main purpose of using a directional receiving antenna is to enhance the signal strength and increase the anti-interference ability. External directional antennas mainly include flat panel antennas, Yagi antennas and logarithmic periodic antennas.
Embedded Antenna mainly refer to the general term for antennas that can be placed inside the device. Built-in antennas mainly include FPC antennas, PCB antennas, spring antennas, ceramic patch antennas, laser direct structuring (LDS) and metal shrapnel antennas.
- When choosing a suitable antenna for the device, first of all, it is necessary to determine whether to choose an internal or external antenna according to the product structure. The external antenna is to install the antenna outside the device;
- external antenna
- High gain;
- It is less affected by the environment, can be used as a standard product, and saves development cycles;
- Take up space and affect the appearance of products.
- Built-in antenna •
- Relatively high gain;
- Mature technology and good product delivery consistency;
- Built into the device, beautiful, no need to do three defenses separately;
- It is greatly affected by the surrounding environment and generally needs to be customized in combination with the product itself.
Post time: Oct-13-2022