Welcome to Zhuhai hanqin cable co.,ltd. In this article, we are going to discuss the performance principle of the Leaky Cable.
Leaky cable is short for leaky coaxial cable, which is a special coaxial cable. Leaky coaxial cable is a special coaxial cable that is slotted at a certain interval and in different forms in the longitudinal direction of the outer conductor of the coaxial cable. The purpose of slotting is to make the electrical signal energy radiate from the cable slot to achieve the purpose of spreading and receiving external radio waves. This radio wave is open, like a hole for radio waves to enter and exit. An open “door”.
The energy of the signal is guided by the length of the leaking cable, and the effective area is limited by the environmental influence of the inner and outer surrounding areas of the cable, so that the signal can continue to enter the mobile communication unit. a) Bamboo knot shape b) Spiral shape c) Lotus shape d) Foam shape like a conventional coaxial cable. The signal transmission depends on the voltage difference between the inner core wire and the outer sheath.
For example, if we intentionally cut a slot to block the current, the current has to surround the slot, which causes the current magnetic field inside the cable to change, so that the slot acts like a coupling antenna and generates radiation. The energy is emitted from the electronic waveguide. Was leaked. This rule applies to the construction of slot antennas in waveguides, so the measurement and description of a slot or a pair of slots often make the method of mapping leaky coaxial cables: leaky coaxial cables can be considered for making coupled antennas. Leaky cables can be divided into two types: radiation type and coupling type according to the different ways of slotting.
a) Radiating leaky cable b) Coupled leaking cable The grooves in the outer conductor of the radiating leaky cable are periodically arranged, and the form of radiation is similar to the radiation of a series of magnetic dipoles distributed along the axis of the leaking cable, and All slots conform to the principle of phase superposition, and the most typical interval is half the wavelength of the transmitted electromagnetic wave signal. The outer conductor of the coupled leaky cable generally has periodic slots of parallel lines. The periodic slot couples out a part of the energy transmitted inside the cable, forming a surface wave outside the cable, and the propagation law of the surface wave is The transmission guided waves in the body are basically the same. The coupled leaky cable rain spoke.
The difference between the leaky cable is that the gap between the grooves of the leaky coupling cable is much smaller than the working wavelength. Therefore, in this coupling mode, the electromagnetic field excites the electromagnetic field through the groove diffraction. Due to the skin effect, the induced resonant charge is only along the shielding. With the movement of the outer surface of the conductor, the leaky cable is like a long display dipole antenna radiating electromagnetic waves, and the coupled leaky cable is like an electronic antenna. The entire leaky cable can be seen as a collection of a series of small antennas.
a Anatomical diagram of TE10 mode electromagnetic wave transmitted by a coupling leaky cable (solid lines are power lines, and dashed lines are magnetic lines of force) b The structure of the electromagnetic field coupling leaky cable at the slot is shown in the figure, and figure b shows the distortion of the electromagnetic field at the slot. , Produced an electric dipole. So how is the electric dipole produced?
In order to explain this problem, according to the principle of electromagnetic conversion, first analyze the situation of the conductor with the same size as the slotted hole. It is assumed that the charge makes a reciprocating simple harmonic motion along the conductor, and a pair of electric dipoles produces a direction in a reciprocating cycle. In this way, the dipole makes a simple harmonic motion with the center of the conductor as the center point in the conductor, and finally forms a series of concentric electric field lines that radiate outwards. According to the principle of reciprocity, on one side of the conductor The conductors with slots of the same area will produce opposite concentric magnetic lines of force, which is the exchange of electric field and magnetic field. The electromagnetic waves coupled at close distances have a concentric structure, but if they are transmitted over long distances, they will be greatly affected by factors such as the surrounding environment and diffraction, and the electromagnetic waves will be interfered when they are emitted outwards, and the space transmission distance will be very limited.
