Open AccessCompact and wideband transmit opto-antenna for radio frequency over fiber
Author(s) -
Olivier Caytan,
Laurens Bogaert,
Haolin Li,
Joris Van Kerrebrouck,
Sam Lemey,
Sam Agneessens,
Johan Bauwelinck,
Piet Demeester,
Guy Torfs,
Dries Vande Ginste,
Hendrik Rogier
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.008395
Subject(s) - wideband , radio over fiber , amplifier , antenna (radio) , antenna tuner , impedance matching , computer science , optics , photodetector , bandwidth (computing) , antenna efficiency , electronic engineering , electrical engineering , radiation pattern , physics , electrical impedance , optical fiber , telecommunications , engineering
An advanced transmit remote opto-antenna unit is proposed that accomplishes impedance matching between a photodetector and a low-profile antenna in a specified frequency bandwidth, without requiring an area-consuming matching network. This results in a highly compact design, which also avoids the losses and spurious radiation by such an electrically large matching circuit. Instead, the photodetector is almost directly connected to the antenna, which is designed as a conjugate load, such that the extracted and radiated power are optimized. The required input impedance for the antenna is obtained by adopting a half-mode air-filled substrate-integrated-waveguide topology, which also exhibits excellent radiation efficiency. The proposed unit omits electrical amplifiers and is, therefore, completely driven by the signal supplied by an optical fiber when deployed in an analog optical link, except for an externally supplied photodetector bias voltage. Such a highly cost-effective, power-efficient and reliable unit is an important step in making innovative wireless communication systems, which deploy extremely dense attocells of 15 cm × 15 cm, technically and economically feasible. As a validation, a prototype, operating in the Unlicensed National Information Infrastructure radio bands (5.15 GHz-5.85 GHz), is constructed and its radiation properties are characterized in free-space conditions. After normalizing with respect to the optical source's slope efficiency, a maximum boresight gain of 12.0 dBi and a -3 dB gain bandwidth of 1020 MHz (18.6 %) are observed.