What Should I Consider When Buying an Antenna Mast?

Antenna tower refers to the tower structure used to support and suspend the antenna. Pole tower structure is a general term for tower structure and pole structure. The tower structure is a high-rise structure with a fixed lower end and a free upper end; a rod structure consists of an upright slender mast with a hinged or rigid connection at the lower end and several layers of wire (wire rope) separated by a certain height along the shaft. The lower end of the wire is anchored to On the ground, use cables to keep the shaft upright and stable.

Antenna tower refers to the tower structure used to support and suspend the antenna. Pole tower structure is a general term for tower structure and pole structure. The tower structure is a towering structure with a fixed lower end and a free upper end. The rod structure consists of an upright slender mast with a hinged or rigid connection at the lower end and several layers of wire (wire rope) spaced a certain height along the shaft. On the ground, use cables to keep the shaft upright and stable.

Chinese name

Mast tower

Foreign name

antenna tower

definition

Antenna tower refers to the tower structure used to support and suspend the antenna.

Construct 2.1 Tower Structure

Tower structures are mainly divided into steel towers, reinforced concrete towers, prestressed concrete towers and wooden towers according to their materials. Most of the steel towers have upper and lower large variable inclination cone structures, and a few towers are straight truncated cones or straight columns. shape. Tower bodies are often made of space trusses or rigid frames, and the cross-sectional shape of the tower body includes triangles, squares, hexagons, octagons, etc. Steel tower components generally use steel pipe, angle steel, round steel and their combined components. Steel tower webs are composed of cross bars and inclined bars. Except for steel towers with triangular cross sections, they need to be changed at certain heights and at different inclination sections of the tower columns. Set the horizontal crossbar everywhere. Steel tower foundations are generally independent reinforced concrete foundations with ground beams placed between the foundations. The tower column of the steel tower on the roof shall be anchored in the reinforced concrete frame column head of the building.

The main forms of reinforced concrete towers are truncated cone, frame and truss. The cylindrical tower body can also adopt different inclination along the height. The cross section of the tower body is annular. The wall thickness of the tower tube is determined by calculation, but it should not be less than 160mm. The wall thickness can be thinned in steps along the height of the tower. The frame and truss tower body forms and foundation forms are similar to steel towers, but the members are mostly prefabricated reinforced concrete hollow pipes or prestressed concrete pipes, which are connected by flanges or embedded parts, and all the members are used on site. Pouring. The basic forms of cylindrical towers are round, ring, square, cone shell and pile foundation.

2.2 Rod structure

The pole structure is composed of a cable, a shaft and a foundation.

(1) Pull line

Set equal or unequal distance along the shaft height. The higher the pole height, the more layers. Generally, three or four cables are arranged at equal angles on each floor. Five cables can be used for double masts (the middle one is between the two rods). Horizontal drawing line), the inclination angle between the drawing line and the ground is preferably 30 ° ~ 60 ° and 45 °. The wire drawing material is often a high-strength galvanized steel wire rope, which is pre-stressed with an open rigging screw buckle (flower basket screw) to enhance the rigidity and overall stability of the shaft. Pull wire ground anchor foundations include gravity, retaining wall, plate and anchor foundations.

(2) Shaft

The shaft can be divided into steel, wood and reinforced concrete according to material. The steel mast adopts an equal-section segmented truss structure, and the segments are connected by flanges or splice plates. The wooden mast is mostly a single log, and the lower layer is also useful for double rods. Reinforced concrete shafts are made of precast concrete pipe by centrifugal method and connected by flanges. The central foundation under the shaft is generally a stepped foundation of concrete or reinforced concrete.

Load, retention, deformation, crack requirements

There are three types of loads: permanent load, variable load and occasional load. Permanent loads include structural self-weight, equipment weight, soil weight, line tension, etc .; variable loads include wind load, ice wrap, snow, earthquake action, temperature, live load on the floor or platform, etc .; accidental load due to broken wires Take the most unfavorable combination of three kinds of loads for design. It is required that the internal force, deformation or crack of the structural member caused by the most unfavorable load does not exceed the allowable value of the resistance, deformation or crack of the structural member.

The control conditions for the deformation, cracks, etc. of the normal use limit state of the high-rise structure shall meet the following requirements: Under the action of wind load (standard value), the horizontal displacement of any point of the high-rise structure shall not exceed 1 / l00 of the height above the ground. For the mast structure, it should also pay attention to the relative horizontal displacement between the cable layers, which must not be greater than 1/100 of the height between the layers. Under the influence of uneven sunlight temperature or wind load (standard value), the angle of the tower body where the microwave antenna is located should meet the requirement that the microwave antenna beam axis deviates from the communication direction by not more than 1/2 of the antenna main lobe width. The maximum crack width of reinforced concrete members should not be greater than 0.20mm.

Tower height and electrical requirements

Tower height and electrical requirements:

(1) The height of the tower should be determined according to the height of the antenna. The position and height of various antennas should meet the requirements of communication technology.

(2) When determining the height of the microwave antenna, the harmful effects of microwave radiation on the human body and the interference caused by the buildings, billboards, various towers and terrains around the antenna near the radio waves should be avoided.

(3) The cables of the masts of long, medium and short wave antennas shall be divided into segments according to electrical requirements by insulators to reduce absorption loss and re-radiation.

Lightning protection ground

The lightning protection device consists of a lightning rod, a down-conductor and a grounding device. Lightning rods should be provided on the top of the tower (pole), and a special down-conductor should be connected to the grounding device. The metal tower (pole) should be connected to the grounding device except as the transmitting antenna.

When the microwave tower is separately grounded, the grounding resistance of the grounding body should not exceed 10; when the short-wave antenna tower is separately grounded, the grounding resistance of the grounding body must not exceed the following table.

Table 1 Ground resistance values of short-wave antenna mast tower grounding body

Soil resistivity ( · m)	100	101 ~ 300	> 300
Grounding resistance ()	10	15	20

When the antenna pole tower is located near the communication building or on the roof, the lightning protection grounding of the pole tower should be combined with the working ground, protective grounding and lightning protection grounding of the telecommunication building room to use a grounding system. Because the grounding requirements of communication equipment are higher than those of antenna pole towers, the grounding resistance value of the joint grounding system should not be greater than the minimum value of the grounding resistance values of various communication equipment in the building. The general requirements are: a microwave tower and microwave equipment room joint grounding system The grounding resistance of the grounding system of the earth station antenna and the communication station of the earth station should not be greater than 4 ; the grounding resistance of the joint grounding system of the antenna tower and the integrated communication building should not be greater than 1 .

Affiliated Facilities

Affiliated Facilities:

(1) When the aviation department requires the setting of navigation marks, a number of red lights should be arranged on the top of the tower and along the height of the tower. If necessary, red and white or yellow and black paint should be painted along the height of the tower.

(2) Set up a working platform at an appropriate height of the microwave tower for antenna installation and maintenance. The platform should be provided with railings with a height of not less than 1.2m.

(3) Ladder shall be set up along the tower body. When the tower body is taller, a rest platform shall be provided.

(4) When a microwave machine room or a sightseeing platform is set on the top of a high tower, an elevator should be added, and water and electricity facilities should be matched accordingly.

(5) When the microwave equipment room and the microwave tower are constructed separately, a bridge should be set up between them to lay various pipelines.

Anticorrosion of pole tower structure

After the steel members are derusted, paint or hot-dip zinc anticorrosion is performed. The latter has good anticorrosive effect and long maintenance period. The wooden poles of the wooden pole tower should be removed from the rotten part, roasted or dried naturally, and then painted with asphalt to prevent corrosion.

Inspection and maintenance

Corrosion, loosening, and slackening of the cable tower components should be overhauled every year, and the tower's verticality should be retested and adjusted. Before the thunderstorm season arrives, the lightning protection grounding system should be inspected at least once, and problems should be handled in time to ensure communication safety.