UHF Four-dipole TV Transmitting Antenna works at Ⅳ and Ⅴ TV frequency (470-860MHz), the antenna unit structure is as shown in Figure1. The antenna plate is composed of four pairs of inclined thick dipole, a reflect plate, a FRP protective cover and necessary coaxial feeder cable. The radiator is a diamond plate dipole. And the feeder part adopts high quality brass, the inner conductor adopts high quality brass and is silver coated. The antenna reflector is made of aluminum alloy plate. The antenna unit has the advantages of wide band, high gain, easy installing and high reliability.
1) System composition
The antenna system is made of sixteen plates of antenna units, sixteen branch feeder cables, and a 1:16 power splitter and a main feeder cable.
2) Technical parameter
Frequency range: 470-860 MHz
Polarization method: vertical polarization or horizontal polarization
Input impedance: 50Ω
Power gain: G≥12dB
Single plate power capacity: ≥digital 1KW
Power capacity: ＞digital 5KW (analog 20KW)
Horizontal field type: non-circularity ＜3dB
Vertical filed type: adopts beam dipping and null filling
System input interface: EIA 15/8 ” flange, EIA 31/8” flange
Work environment temperature: -600C~+800C
Rated wind velocity: >180KM/h
Install method: Omni-directional or special array
3) Work principle
The output power of the transmitter is sent to the power splitter via the main feeder cable, step Chebyshev impedance changing and power distribution are processed inside the power splitter, and then the power is sent to the antenna units by the branch feeder cables. The antenna units will convert the RF power to electromagnetic wave to be radiated into the free air, so as to finish the converting from RF power to space electromagnetic wave. The directional figure of the system is as shown in Figure 3.