A kind of leaky coaxial cable
Technical field
The utility model relates to a kind of cable, relates in particular to leaky coaxial cable.
Background technology
In recent years, the fast development of mobile communication industry, the colony that the mobile subscriber of various demands forms is increasing, correspondingly also more and more higher to the requirement of mobile communication service quality.Concerning any wireless system, it is the basic requirement of one item that the high-quality of signal covers.A kind of effective transmission medium that leaky coaxial cable covers as the solution signal obtained development to a certain degree in recent years, it is a kind of open transmission line, slotted eye by the setting of katal on coaxial cable outer conductor shape, just can make the electromagnetic signal and the space outerpace generation mutual coupling of transmission in the cable, thereby make the dual-use function of this cable with transmission and electromagnetic radiation signal, thereby solve the signal covering problem of the weak blind place of wire wireless communication system, use in large quantities in subway, tunnel, mountain area etc.
At present, though there are some leaky coaxial cables using on the market, its slotted eye generally takes the shape of the letter U, splayed etc., the shortcoming of these cable ubiquity radiation directionality differences.In covering engineering, leak the mode that cable all adopts side to lay, make the greatest irradiation direction of cable face moving body with Louing.If used leakage cable radiation directivity is bad, just has in a large number and exist with the side direction signal dorsad; And this part signal can not be moved effectively reception of body, so must suppress it.The application just is being based on above-mentioned background and the design improvement of carrying out.
The utility model content
Thereby the technical problems to be solved in the utility model provides a kind of can effectively the inhibition and leaks cable improves the leakage cable dorsad with the generation of side direction signal radiation directivity, makes the directed leaky coaxial cable of concentrating of emittance.
In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is: a kind of leaky coaxial cable, from nexine to skin successively by inner wire, insulator, outer conductor, sheath is formed, described outer conductor upper edge cable axially offers several slotted eyes, described slotted eye is periodic distribution on outer conductor, each cycle comprises a basic slotted eye unit, one is the symmetrical cell of basic slotted eye unit on cable is axial, described basic slotted eye unit pack is drawn together two at the cable symmetrical slotted eye that directly makes progress, and each slotted eye is by along the axially extended axial hole of cable, be positioned at axial hole one end and go up the hole and be positioned at the axial hole other end and form along the circumferential following hole of extending down of outer conductor along the outer conductor circumference is upwardly extending.
Further, described axial hole, go up the hole and the hole in hole is wide basic identical down, described hole is wide to be defined as distance between the relative hole wall in every kind of hole.
Apart distance is wide close with described hole between two slotted eyes of described basic slotted eye unit.
Distance between described basic slotted eye unit and the symmetrical slotted eye unit is 2~4 length that the hole is wide.
Described outer conductor wraps on the insulator and the pre-copper belt that described slotted eye is arranged that dashes for vertical.
In the mode to enforcement that technique scheme is optimized, also wrapped one deck heat insulating belt between described outer conductor and the sheath.
Because technique scheme utilization, the utility model compared with prior art has following advantage: the utility model is by improving the slotted eye on the outer conductor, make slotted eye outer conductor axially and circumferential distribution arranged all, because slotted eye is the radiation source of leaky cable, adopt the cable of the utility model slotted eye design, the complex method of radiation source has obtained optimization, the overall alignment structure and the arrangement pitches of slotted eye, make it have lower coupling loss and higher directed radiation, transmission attenuation is little, this signal strength that leaks the cable overlay area can satisfy the instructions for use that the wire wireless telecommunication system signal covers greater than common leakage cable 2~3dB under the equal conditions.
Description of drawings
Accompanying drawing 1 is the front view of the utility model leaky coaxial cable;
Wherein: 1, inner wire; 2, insulator; 3, outer conductor; 31, slotted eye; 311, axial hole; 312, go up the hole; 313, following hole; 4, heat insulating belt; 5, sheath;
Embodiment
Below in conjunction with accompanying drawing, the utility model preferred embodiment is elaborated:
Leaky coaxial cable as shown in Figure 1 is made up of inner wire 1, insulator 2, outer conductor 3, heat insulating belt 4 and sheath 5 successively from nexine to skin.In the present embodiment, inner wire 1 adopts copper tube, insulator 2 is made by the physical blowing polyethylene, outer conductor 3 is selected for use in advance and is wrapped on the insulator 2 towards the copper belt of grooved hole 31 is vertical, and before outer conductor 3 vertical bags, in order further to increase the bendability of cable, can do wrinkle treatment by roller on its surface.Heat insulating belt 4 is wrapped on outer conductor 3, and it both can play effect of heat insulation, again fixing outer conductor 3.Sheath 5 adopts low-smoke halogen-free flame-retardant sheath to extrude in heat insulating belt 4 peripheries.
To be described in detail the slotted eye on the outer conductor 3 31 below:
In the utility model, slotted eye 31 distributes on outer conductor and along the cable axial cyclic, each cycle comprises four slotted eyes, wherein, per two adjacent slotted eyes form a slotted eye unit again, for convenience of description, at this one of them slotted eye unit is called basic slotted eye unit, another slotted eye unit then is the unit of symmetry in the axial direction, this basic slotted eye unit, be referred to as symmetrical slotted eye unit, Fig. 1 has provided the signal of one-period slotted eye, supposes that two slotted eyes in left side are basic slotted eye unit, and then two slotted eye unit, right side essence is the axial symmetrical cell of basic slotted eye unit, left side.
And for wherein basic slotted eye unit, as seen from Figure 1, it is made up of two slotted eyes 31 again, and two slotted eye 31 diametrically opposed titles.Each slotted eye 31 by along the axially extended axial hole 311 of cable, be positioned at axial hole 311 1 ends and go up hole 312 and be positioned at axial hole 311 other ends and form along outer conductor 3 circumferential following holes 313 of extending down along outer conductor 3 circumference are upwardly extending.Wherein, axial hole 311, go up hole 312 and the hole in hole 313 is wide basic identical down, so-called hole is wide to be defined as distance between the relative hole wall in every kind of hole.Simultaneously, the same length in last hole 312 and following hole 313, the length of axial hole 311 is last hole 312 or time hole 313 length 3~6 times.
For two slotted eyes of two basic slotted eye unit, apart distance is about the wide distance in above-mentioned hole between it, and the distance between basic slotted eye unit and the symmetrical slotted eye unit can be set at 2~4 distances that above-mentioned hole is wide.
Because the slotted eye of opening on outer conductor 3 31 is radiation sources of leaky cable, the performance of leaking the cable radiation field intensity finally is to determine by shape, arrangement architecture and the arrangement pitches of this slotted eye are common.Adopt above-mentioned slotted eye design, the last hole 312 of each slotted eye 31, following hole 313 constitute a pair of symmetrical drive source, thereby have improved the radiation directivity of this product.Because theoretically, the symmetrical drive source electromagnetic field directivity of inducing is stronger.Simultaneously, the corner shaped design of this slotted eye has been improved the boundary value condition of radiation source, has effectively increased the level of disruption of radiation source, improves the radiation intensity of field source significantly.But if be single slotted eye 31 only as a radiation unit source independently, the main lobe width of its radiation field is broad still, promptly directivity a little less than.In antenna theory,, usually several element antennas (being array element) are arranged in antenna array by certain mode in order to improve the radiation directivity of antenna.As long as the amplitude and the phase place of electric current satisfy suitable relation on each array element of antenna array, can obtain needed radiation characteristic.The utility model leakage cable carries out symmetry to N slotted eye 31 radiation sources along the cable axis direction exactly and lays, thereby constitutes a kind of uniform straight line array, has improved the radiation directivity that leaks cable preferably.
To sum up, the utility model leaks cable can satisfy the radiation requirement better, and the complex method of radiation source is optimized more, and the coupling loss of leaking cable is lower, has higher directed radiation simultaneously, and transmission attenuation is little.This signal strength that leaks the cable overlay area can satisfy the instructions for use that the wire wireless telecommunication system signal covers greater than common leakage cable 2~3dB under the equal conditions.