The function of the feeder and the jumper are both connection and transmission models, and both serve as the medium for connecting devices or equipment. The main difference between the two is the connection distance and softness.
Feeder: RF cable that transmits RF signals. A coaxial radio frequency cable generally used for the transmission of radio frequency signals from BTS equipment to antenna feeders. The length is longer, the general dimension is larger, and the 7/8″ feeder has lower loss as the backbone.
Jumper: a short cable (or optical fiber) connecting equipment and devices. The essence is not much different from the feeder, but because the bending radius is small and soft, it is used to connect the feeder and the antenna, and the feeder and the BTS equipment, and the length is shorter. Another kind of jumper is fiber jumper, which connects optical transmission equipment in short distance. The optical fiber jumper reduces the loss to a minimum because the optical fiber has almost zero loss in transmission through photoelectric conversion.
Jumpers are divided into indoor jumpers and outdoor jumpers. The connection line from the arrester to the combiner (or surf) is called an indoor jumper, which is generally 3 meters long. Commonly used connectors are 7/16DIN type and N type. There are straight and elbows. Outdoor jumper is also called small antenna antenna. It is the connection line connecting the 7/8 “main feeder and the lower interface of the antenna. Normally it is 2 meters (this is the case produced by Datang Telecom). Indoor jumpers are generally soft jumpers. Therefore, in the case of sufficient resources, do not exchange indoor jumpers for outdoor jumpers. In addition, indoor and outdoor jumpers are divided into pressure heads and manual heads.
The feeder is a very long line from the arrester to the outdoor jumper. The main function of the feeder is to efficiently send the radio frequency carrier signal output by the transmitter to the antenna. On the one hand, the attenuation of the feeder is required to be small, and on the other hand, its impedance should match the output impedance of the transmitter and the input impedance of the antenna as much as possible. .
(1) Antennas mainly include the following types:
A) Suction cup antenna: moderate price, convenient installation, moderate gain, suitable for installation on moving vehicles, or adsorption on metal objects. Generally, the gain is 2.6dB, 5dB, etc.
B) Anti-theft antenna: moderate price, easy to install, with the same gain as a suction cup antenna. When installed outside of a metal box, it cannot be removed from the outside of the box, so it is called an anti-theft antenna.
C) Low-gain omnidirectional antenna: The gain is 3.5dB, and the installation requires a fixed bracket, which is suitable for long-distance multi-point transmission.
d) High-gain omnidirectional antenna: The gain is 8.5dB, and the installation requires a fixed bracket, which is suitable for long-distance multi-point transmission.
E) Directional antenna: The gain is very high, 12dB, and the installation requires a fixed bracket, which is suitable for long-distance transmission in a fixed direction
(2) Feeders mainly include the following types:
A) The feeder loss of 50-3 (impedance 50Ω, cross-section 3) is 0.2dB/m.
B) The feeder loss of 50-7 (impedance 50Ω, cross section 7) is 0.1dB/m
C) The feeder loss of 50-9 (impedance 50Ω, cross section 9) is 0.07dB/m.
The feeder is an important equipment connecting the radio and the antenna
The TPA module is a TD-SCDMA power amplifier unit. The TPA is located between the RFU and the smart antenna subsystem. It consists of a low-noise amplifier in the upstream direction and a multi-carrier power amplifier transceiver switch in the downstream direction, as well as a control and alarm unit. It provides the necessary radio frequency power to the antenna and pre-amplifies the received signal to a certain level to meet the further processing requirements of the RFU. Because the TPA module is directly close to the antenna array, it can reduce cable loss and improve the effective transmit power of the antenna and the system’s receiving sensitivity.
A TDB09A TPA box contains 4 antenna power amplifiers. Two TPA boxes form an 8-channel antenna power amplifier, which is connected to an 8-period smart antenna.
