Radio and Power over Fiber System for 4K/8K Satellite Antenna

概要

In the new 4K/8K satellite broadcasting, the maximum intermediate frequency (IF) is proposed to be changed from 2071 MHz to 3224 MHz. The coaxial cable has been widely used for IF signal transmission, but the attenuation is significant with a high signal loss when a high-frequency signal is transmitted. With the increasing number of 4K/8K channels and the development of broadcasting technology, the frequency used for the IF signal will keep increasing. Therefore, the coaxial cable may not meet the future ultra-high-definition satellite broadcasting requirements anymore. Compared to the all-electrical signal transmission, the Radio-over-Fiber (RoF) system can achieve signal transmission with lower loss and reduce noise sensitivity by transmitting the signal through an optical fiber.

In this work, we propose a system that uses the RoF technology to reduce the signal loss during high-frequency transmission while adopting the Power-over-Fiber (PoF) technology to generate electric power for Low-Noise Block (LNB) and RoF unit on the antenna side. A method that combines the RoF technology and PoF technology into one Double-clad Fiber is also reported. With the comparison between the signal transmitted through an RoF system and that through a coaxial cable, it can be clearly shown that the advantage of the RoF technology in the signal loss performance. The experimental results of signal transfer demonstrate that by using the RoF technology, the average amplitude of the effective signal containing TV channels increases by 8.89 dB in the range of 2224-3224 MHz, while the average amplitude increases by 5.7 dB for the effective signal in the range of 1032-2071 MHz.

The comparison between coaxial cables and RoF technology shows that changing the size and material of coaxial cable can not solve the problem of serious attenuation of the high- frequency signal. The system using the RoF technology showed better performance, especially as the frequency increased.

The high-frequency signal transmission experiment demonstrated that comparing with the coaxial cable, RoF technology shows a great advantage in attenuation to ensure that the signal loss will not worsen when the maximum IF is increased higher than 3224 MHz in the future.

The experiment's result on the comparison between optical and electrical signal splitter demonstrated that, in every different frequency range, the RoF technology with a 50:50 signal splitter has a remarkable advantage in signal loss performance compared with the coaxial cable with an electrical 50:50 signal splitter.

Finally, the experiment results on power transfer indicated that the PoF system could be used for a long time and generate a stable electrical power output to supply LNB and RoF transmitter's power consumption.