Radio over fiber is a solution to overcome the limitations of radio communication range, namely by superimposing radio or microwave signals on fiber-optic networks. The advantages of using RoF include low attenuation, wide bandwidth, immunity to electromagnetic interference, easy installation and maintenance, and low consumption. low electrical energy. Some of these things are the reasons for using RoF for the weaknesses of radio network propagation.

Interested in the topic of optimum signal on the radio over fiber, Yus Natali did more research on this in his dissertation. The research results were presented at the Doctoral Promotion Session held by the Faculty of Engineering, Universitas Indonesia, on Wednesday (28/12). Yus Natali raised the theme “Investigation of Transmission Areas on Electro-Optic Modulators to Determine the Optimum RF Input Signal in Radio Over Fiber Networks.”

“Radio over fiber is a hybrid system of a wireless communication system and an optical fiber communication system that is utilized for cellular network fronthaul. Green DAS (Distributed Antenna System) is RoF used for cellular networks in buildings. Some of the performance of RoF is determined by the antenna and the electrical-to-optical conversion device, in this case, the EO (electro-optical) modulator. Antenna integration as EO conversion for downlink direction RoF can be done by integrating the receiving antenna and EO modulator in one device as one of the future solutions in terms of compactness,” said Yus Natali.

The tool works as an external EO antenna and modulator. The problem with this integration is the limited RF power that can be received by the device. This can also occur with conventional single antennas which require a reflector to optimize the RF input signal. Optimization of the RF input signal can be in the form of increasing the electric field in the integration antenna or increasing the power received by the antenna so that the EO conversion can be successful.

The initial stage of the research was to design a single bowtie antenna to optimize the RF input signal. Simulation of bowtie antenna integration by utilizing optical materials, SiO2, and optical waveguide to obtain a larger electric field value so that the EO conversion can be successful. The EO conversion mechanism will be optimal when it works like MZM (Mach Zehnder Moduator).

The second step in the research is to optimize the RF input signal by adjusting the amplitude of the RF signal so that it is in the MZM transmission area it can limit harmonic distortion at the MZM output. The RF input signal represented by the signal generator is set so that the output RF signal works in the MZM transmission area. This transmission boundary area method can be applied to RoF networks by reducing the number of optical components or equipment by implementing an RoF network without optical amplifiers, without optical filters, or other optical devices in RoF networks.

“It is hoped that this research can provide new information to overcome the limitations of radio communication range. Indeed, further research is needed to overcome this weakness of ROF. So that in the future the use of RoF to overcome the weaknesses of radio network propagation can be more widely implemented,” said the Dean of FTUI, Prof. Dr. Heri Hermansyah, ST., M.Eng., IPU.

Yus Natali won a Doctorate with the title of Very Satisfactory at the Doctoral Promotion Session. He is the 151st Doctor who graduated from the Department of Electrical Engineering and the 485th Doctorate at FTUI. The doctoral promotion session was chaired by the Chairman of the Session, Prof. Dr. Ir. Harry Sudibyo S., DEA with Promoter, Prof. Dr. Ir. Eko Tjipto Rahardjo, M.Sc. and Co-Promoter, Ir. Purnomo Sidi Priambodo, M.Sc., Ph.D. The Examiner Team consists of Dr. Bambang Widiyatmoko, M.Eng., Prof. Dr. Fitri Yuli Zulkifli, S.T., M.Sc., Prof. Dr. Ir. Retno Wigajatri Purnamaningsih, M.T., and Dr. Ir. Catur Apriono, S.T., M.T., Ph.D.


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Faculty of Engineering, Universitas Indonesia