Leaky coaxial cable

Advantages

Compared with the traditional antenna system, the leaky coaxial cable antenna system has the following advantages:

1. The signal coverage is uniform, especially suitable for narrow tunnels, etc. Space;

2. Leaky coaxial cable is essentially a broadband system, some types of leaky cables can be used in CDMA800, GSM900, GSM1800, WCDMA, WLAN and other systems at the same time;

3. Although the price of leaky coaxial cable is more expensive, it can greatly reduce the overall cost when multiple systems are introduced into the tunnel at the same time.

The use of leaky coaxial cable can be used in areas where general communication antennas are difficult to function, especially in areas where discrete antennas for mobile communication systems cannot provide sufficient coverage, such as mountainous areas, hills, tunnels, and Underground railways, mines, underground buildings, shopping malls or other blind areas for electromagnetic field propagation. In these areas, due to the narrowness and obstruction of the surrounding environment, the antenna coverage is greatly restricted, and because it is very close to the covered object and the signal radiation direction is perpendicular to the radiation environment, it can provide uniform field strength. Therefore, for wireless signal receiving devices in these environments Leaky coaxial cable is the best wireless coverage method.

Main indicators

The main indicators of the electrical performance of leaky coaxial cables are longitudinal attenuation constant and coupling loss.

1. Longitudinal attenuation

The attenuation constant is the most important characteristic for evaluating the energy loss of electromagnetic waves transmitted inside the cable.

The signal inside the ordinary coaxial cable becomes weaker with the transmission distance at a certain frequency. The attenuation performance mainly depends on the type of insulation layer and the size of the cable.

For leaky cables, the surrounding environment will also affect the attenuation performance, because a small part of the energy inside the cable is transmitted in the external environment near the outer conductor. Therefore, the attenuation performance is also restricted by the arrangement of the outer conductor slots.

2. Coupling loss

Coupling loss describes the index of the amount of energy received by the external antenna due to coupling outside the cable, which is defined as: at a certain distance, received by the external antenna The ratio of energy to the energy transmitted in the cable. Since the influence is mutual, a similar method can also be used to analyze the signal transmission from the external antenna to the cable.

The coupling loss is affected by the interference or reflection of the cable slot form and the external environment on the signal. In a wide frequency range, the stronger the radiation means the lower the coupling loss. According to the different coupling mechanisms between the signal and the outside world, there are mainly three types of leaky coaxial cables:

·Radiation type (RMC)

·Coupling type (CMC)

·Leakage Type (LSC)