Radiating Cables

The leaky cable structure is similar to that of a normal coaxial cable, except for the outer conductor. To ensure the transmission of electromagnetic waves from one end to the other, ordinary coaxial cables use the largest transverse fully shielded outer conductor, which prevents signals from penetrating the cable and minimizes the loss of electromagnetic energy during transmission. Leaky cable intentionally cuts slots of different sizes and angles on the outer conductor, allowing electromagnetic energy to leak from the inside of the cable to the outside in a controlled manner. At the same time, electromagnetic energy outside the cable will also be induced into the cable, but most of the energy inside the cable will still be transmitted forward along the direction of the cable. The function of a leaky cable is similar to that of a combination of a transmission line and an antenna, guiding electromagnetic waves forward and enhancing field strength coverage along the line.

Leaky cable can be divided into coupling type and radiation type.The coupling type leaky cable has a relatively regular slot, with less longitudinal energy, which rapidly decreases with increasing distance, making it suitable for broadband transmission. The radiation type has irregular non-periodic slots with a spacing comparable to the wavelength (or half wavelength), and electromagnetic energy is radiated from the slots on the outer conductor, with a narrow directional frequency band but a long radiation distance. The specific slot arrangement of the radiating leaky cable can reduce transmission loss and does not decrease rapidly with increasing distance.

Therefore, different types of leaky cables can be selected according to different application scenarios, such as radiating leaky cables for tunnel communication and coupling leaky cables for indoor distribution systems.