An antenna is a device that emits radio frequency signals from a coaxial cable source into the air or receives them from the air onto a coaxial cable. It converts the guided waves scattered on the coaxial cable into radio waves scattered in unbounded media, or performs reverse conversion. If you make the wrong choice, you will not receive the expected functionality, and in severe cases, you may even burn out the module
The design and selection of antennas is a crucial part of the wireless network receiving and transmitting equipment used in frequency transmission system software. Excellent antenna system software can achieve optimal communication spacing. The size of the same type of antenna is positively correlated with the optical wavelength of the RF signal, and the lower the frequency of the data signal, the larger the required antenna.
The classification of 01 antennas can be divided into external antennas and internal antennas based on the installation location. Antennas installed inside the machine equipment are called internal antennas, and antennas installed outside the machine equipment are called external antennas.
For small-sized products such as handheld machine equipment, wearing design schemes, and smart home systems, built-in antennas are widely used, which have high processing speed and beautiful appearance. IoT technology and smart products must be connected to the network to transmit data, so antennas must be used.
The smaller the indoor space and the more frequency bands, the more complex the antenna design scheme. External antennas are generally all standard materials, and can be applied by purchasing antennas in the required frequency band without adjustment.
For example, express delivery boxes and vending machines, which are widely used with magnetic external antennas, can be attached to a white metal casing. This type of antenna cannot be placed inside a metal file cabinet, as metal materials will shield the antenna data signal. Therefore, it can only be placed outside. The article provides a detailed introduction to the basic information of the antenna, focusing on the classification and model selection of the antenna.
1.1 External antenna
The key to built-in antenna refers to the antennas that can be placed inside machine equipment. The key to built-in antenna includes FPC antenna, PCB antenna, spring antenna, ceramic patch antenna, laser immediate forming technology (LDS), and hardware spring patch antenna.
Model 02 Selection Manual: When selecting a suitable antenna for machine equipment, it is necessary to first clarify whether to use an internal or external antenna based on the product structure. The main characteristics of external antennas and internal antennas are as follows:
External antenna
High gain with little environmental harm, can be used as a standard product, saves development progress, occupies indoor space, and poses a threat to the aesthetic and elegant appearance of the product
Built in antenna
Relatively high gain, complete processing technology, good consistency in product delivery, built-in in machine equipment, beautiful and elegant, no need for independent three protection against environmental hazards, generally must be integrated with customized products
2.1 Selection of External Antenna Models
Firstly, it is necessary to clarify the coverage area of the machine equipment data signal. The coverage direction of the data signal is determined by the radiation source direction diagram of the antenna. According to the radiation source direction of the antenna, the antenna is divided into omnidirectional antenna and fixed term antenna.
2.1.1 External omnidirectional antenna
Glass suction cup antenna: With relatively high gain, it is characterized by a strong magnetic glass suction cup, which is easy to install and fix. However, the glass suction cup must be attached to the metal surface. In the field of wireless modules, glass suction cup antennas are often used in conjunction with wireless modules to achieve the goal of improving the communication distance between wireless modules, such as wireless intelligent meter reading, vending machines, express delivery boxes, car radios, etc.
Copper rod glass suction cup antenna: Similar to the general whip shaped glass suction cup antenna, but its advantages over whip shaped glass suction cups depend on the use of a large diameter all copper radiator, which has low Euro losses, high antenna efficiency, and wide network bandwidth coverage. Applicable to data transmission stations with relatively high performance specifications, and image transmission with moderate horizontal spacing.
Hot melt adhesive rod antenna: It is a common external antenna with moderate gain and relatively cheap price, commonly used in wireless communication control modules, wireless routers, data transmission radios, etc. According to the indoor space regulations for installation, antennas with suitable specifications and sizes can be selected. The selection of antenna specifications is related to the gain. Generally, the longer the length of the same frequency band, the higher the gain.
Fiberglass corrosion-resistant antenna: In omnidirectional antennas, the performance of fiberglass corrosion-resistant antennas is mainly superior, with the core being an all copper oscillator and using a balanced explosion-proof switch, which is less environmentally harmful; The casing is made of high-quality fiberglass anti-corrosion material, which has excellent three protection characteristics and is well integrated into extreme geographical environments. Especially suitable for long-distance gateway IP data signal masking, image transmission, etc.
2.1.2 External directional antenna
It is generally used in natural environments with long-distance communication, small data signal coverage area, and high overall target density, with extreme examples being point-to-point long-distance communication.
Tablet antenna: High efficiency, small size, easy to install, capable of combining gain and radiation source areas. Network signal coverage can be used in rooms and tunnel construction, data signal transmission at medium horizontal intervals, image transmission, and data signal crossing walls.
Yagi antenna: With high gain, slightly larger volume, strong specificity, and the need to pay attention to the antenna's orientation during application, it can be used for long-distance data signal transmission, image transmission, and direction finding.
Most cycle time antennas: Ultra wideband antennas with very wide network bandwidth coverage, with a network bandwidth of up to 10:1, commonly seen in data signal enlargement, room coverage, and elevator car data signal coverage.
2.2 Selection of built-in antenna models
The shape of the built-in antenna can be divided into FPC/PCB/spring/porcelain/hardware spring plate/laser immediate forming technology (LDS) and other types. At present, PCB antennas are generally chosen more frequently. When selecting spring LDS antennas with high cost management and average performance regulations, the general built-in antennas are all environmentally hazardous and must be designed with customized solutions or matched with resistors.
FPC antenna: With excellent cost-effectiveness, it can match various external color tones after oil pumping; The product has good flexibility and can perfectly meet the standard curved surface; The processing technology is perfect and stable, the production cycle is fast, and the delivery of large quantities is good; Applicable to antenna design schemes for broadband intelligent products with high performance requirements.
PCB antenna: The significant difference from FPC antenna is that FPC has very good flexibility. PCB antenna is a hard board, and in construction and installation, if it must be bent and curved, FPC antenna can be selected. If it is a flat plan, PCB antenna can be selected, which is easier to install than FPC.
Spring antenna: Its major feature is low price, but it has low gain and bandwidth. When it is built-in in the product, it is usually necessary to adjust the antenna pairing.
Porcelain patch antenna: occupying little indoor space and performing well; Bandwidth makes it difficult to ensure multiple frequency bands; Reasonably improving the integration of computer motherboards and reducing the limitation of antennas on IDs; The design scheme must be introduced at the beginning of defining the computer motherboard.
LDS antenna: suitable for a unique external surface antenna, can flexibly use indoor space of the antenna; The completion of antenna performance is closer to the physical limits of the natural environment; There are unique material regulations for the shell or support frame on which the antenna is attached; The processing technology is complete and there is a certain degree of non conformance throughout the entire process, depending on the paint color.
