A Fully Bidirectional 2.4-GHz Wireless-Over-Fiber System Using Photonic Active Integrated Antennas (PhAIAs)

Abstract

Abstract-This paper describes a low-cost scheme for implementing in-building distributed antenna systems using the photonic-active-integrated-antenna (PhAIA) concept, whereby photonic devices are integrated directly with planar antennas. Deembedded input impedance is measured for an 850-nm verticalcavity surface-emitting laser and photodiode from 0-10 GHz, and the devices are matched directly to the nonradiating edge of a rectangular-microstrip-patch antenna. Link gain, 1-dB compression point, and spurious-free dynamic range are measured in the links. The fully bidirectional system, which is far from being completely optimized, is then tested over a 300-m laboratory-based multimode fiber link and a 220-m in-building dark-fiber link. Results are shown for throughput and signal-to-noise ratio, and this paper shows that such systems can achieve up to 10-m RF range, at reduced throughput, with no RF amplification.

A 2.4-GHz Wireless-Over-Fibre System Using Photonic Active Integrated Antennas (PhAIAs) and Lossless Matching Circuits

“…This difference is due to variations in the coupling from MMF into the PD. The input impedances of the PDs and VCSELs have already been measured in [7].…”

“…These Distributed Antenna Systems (DASs) often employ high specification lasers and RF amplification in order to achieve good link gain and large RF ranges from remote antenna to the user. However, there are opportunities for very low cost modules with reduced RF ranges giving room-scale coverage of 5-10 m [7], [8]. In [8] a range of 5 m was shown with a carrier frequency of 60 GHz using an electroabsorption modulator (EAM) based scheme which requires no laser at the remote end of the link.…”

“…However, EAMs are not low cost and can suffer from low responsivity and be polarization sensitive. The approach outlined in [7] shows that low cost vertical cavity surface emitting lasers (VCSELs) can be used within the photonic active integrated antenna (PhAIA) concept [7], [9] which enables integrated modules with no RF amplification to be used at the remote end. The use of VCSELs with low bias current requirements and the removal of RF amplification and associated DC biasing circuitry results in a very low DC power budget, in the order of 10 mW, at the remote end which opens possibilities for DC power-over-fibre operation [10], further reducing implementation costs.…”

“…The use of VCSELs with low bias current requirements and the removal of RF amplification and associated DC biasing circuitry results in a very low DC power budget, in the order of 10 mW, at the remote end which opens possibilities for DC power-over-fibre operation [10], further reducing implementation costs. In [7] peer-to-peer operation was shown in combination with simple matching based on variation in antenna input impedance with contact position on the non-radiating edge of the antenna. Here, a number of further developments are presented.…”

“…In this work, a live access point and matching circuits are employed for both uplink and down link PDs. The VCSELs used happen to have input impedances that are almost purely real and close to 50 at 2.4 GHz [7] and therefore simple matching can be used in this case. The PDs on the other hand are very capacitive in nature and thus the use of lossless matching circuits can remove the resulting mismatch loss and can theoretically improve the link gain by up to 8 dB in both up and down links.…”