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We present the implementation and demonstration of a software tool for the performance characterization of integrated N-by-1 photonic beamformers for phased array antennas. The software operates the automatic measurement of the transmission parameters of an equivalent N+1 ports microwave network, corresponding to the complex excitations of the individual antenna elements of the array. The measured excitations are used to simulate the array factor generated by the optical beamformer and to analyze it in terms of maximum directivity, sidelobe levels and wideband behaviour. The software provides a useful tool to test the wideband performance of the network, the effects of excitation inaccuracies, and a straightforward evaluation of the effects of amplitude and phase weighting for beam shaping.

Link Aggregation is a mechanism used in enterprise networks to bundle Ethernet links. This paper proposes the use of such techniques in the Broadband Photonics (BBP) Network. This network is a dynamically re-configurable photonic access network.

We investigate a way of generating an RF local oscillator (LO) signal by means of optical heterodyning of two lasers. This LO signal will be used to down-convert a Ku-Band(10.7 GHz12.75 Ghz)RF signal from a phased array antenna (PAA) to an intermediate frequency 950 MHz to 3 GHz) at the mixer. In this paper we have modeled the laser spectrum perturbed by phase noise. In addition, we analyze the impact of the lasers phase noise on the quality of the gererated LO by optical heterodyning.

We compare the effects of low biasing and push-pull modulation on the spurious-free dynamic range (SFDR) of an analog photonic link (APL) architecture employing a pair of directly-modulated laser diodes and a balanced photodetector.

We investigate the externally generation of an LO signal by optical heterodyning, which is then distributed to each of the mixers at every antenna element of a phased array antenna used for standard DVB-S (digital Video Broadcasting-Satellite) reception system. The system1 is presented in Figure 1. The Ku-Band (10.7 GHz ~12.75 GHz) RF signal from the antenna array is amplified and then down converted to IF (950 MHz to 2150 MHz) at the mixer by a 9.75 GHz LO signal generated by optical heterodyning

The paper discusses the merits of having a reconfigurable access network. The network is viewed as a stack of logical PONs in which bandwidth can be redistributed on an inter-PON scale. The redistribution allows for optimal distribution of bandwidth to the end user.

We demonstrate an analog photonic link with a high multioctave spurious-free dynamic range (SFDR) of 119 dBHz2/3. The link consists of a pair of semiconductor DFB lasers modulated in a push-pull manner and a balanced photodetector. With precise amplitude and phase matchings, a signal enhancement of 4.5 dB and a second-order intermodulation distortion suppression of 40 dB relative to the case of a single arm optical link with one laser can be achieved. To our knowledge, the measured SFDR is one of the highest broadband value ever achieved with directly modulated lasers. Index Terms—Intermodulation distortion, laser noise, optical modulation, semiconductor lasers

For enhanced communication on board of aircraft, novel antenna systems with broadband satellite-based capabilities are required. So far existing L-band satellite based systems for communications are used primarily for passenger application (APC) or administrative communications (AAC); initially analogue voice and now data are tending to evolve towards broadband digital applications. Many studies are going on worldwide to employ Ku-band TV geostationary satellites for communication with mobile terminals on aircraft. For a short period broadband internet was available on aircraft via Connexion by Boeing (CBB) services. Lufthansa installed the CBB system on some of their long-haul aircraft. In the EC Sixth Framework Programme ANASTASIA (Airborne New and Advanced Satellite techniques and Technologies in A System Integrated Approach) existing and planned aeronautical SATCOM services, systems and technology have been analysed. It has been concluded that for cockpit services, L-band systems (namely Inmarsat, MTSAT, Iridium and Globalstar) are clearly most suitable, whilst Ku-band systems have appeal for passenger services

One of the key research topics of the Telecommunication Engineering (TE) Group at the University of Twente (UT) is RF Photonics. The aim of this field is to develop schemes that utilize the advantages of optical technology for performing RF functions in wireless communication systems. Examples of such functions are high-frequency filtering, frequency conversion, antenna remoting, and beam forming for phased array antennas. The TE Group is currently involved in several Senter and NIVR projects on RF Photonics that are related to phased array antenna applications.

A novel squint-free, continuously tunable beamformer mechanism for a phased array antenna system is proposed. It consists of filter-based optical single-sideband suppressed-carrier modulation, a fully integrated optical beam forming network using cascades of optical ring resonators as tunable delay elements, and balanced coherent optical detection. The proposed system brings advantages in optical bandwidth requirement, system complexity, and dynamic range, without introducing the problem of beam squint or limited tuning resolution. Some experimental results are presented in order to demonstrate the feasibility of the proposed concept.

The activities of the Telecommunication Engineering (TE) group span the communications spectrum from copper cables, optical fibres, microwaves, radio and electromagnetic compatibility. Our research concentrates on optical signal processing and networks, mobile communications, microwave techniques and radiation from ICs and PCBs [1]. A considerable (and particularly interesting) part of it is related to optical beam forming for phased array antennas, using optical ring resonators. In this article the theoretical basics and practical challenges of this interesting research topic will be summarized.

In this paper we investigate the performance degradation in a wavelength division multiplexing network due to crosstalk in optical cross-connects. Worst-case analysis is carried out including in-band crosstalk components. In contrast with the approximate methods in the literature, all beat-noise terms are included, and both input signal hypotheses are considered. The results are obtained by using appropriate importance sampling strategies. The optimization of importance sampling parameters was done with new adaptive techniques based on stochastic Newton recursions, combined with a novel technique called the g-method. Accurate performance measures for practical system parameter values are obtained in short simulation run-times. Infinite and finite extinction ratios are considered. The results indicate that the detection threshold has a strong impact on the system performance. The importance sampling techniques are also useful for the optimization of this system parameter.

In this paper exact analytical expressions of the power spectra of a Manchester coded CPFSK signal with arbitrary modulation index are derived. For the signal after delay & multiply demodulation exact analytical expressions of the power spectra with modulation index 1 are derived, and computer simulations are used to calculate these spectra for various modulation indices. Moreover, the analytically derived power spectra are verified by computer simulations. The simulation results correspond extremely well with the analytically calculated spectra. These signal spectra are important for the design and construction of the pre and post detection filters in the receiver.

An optical-router-based dynamically reconfigurable photonic access network is described. The network is a dense wavelength division multiplex overlay over legacy time division multiplexed passive optical networks (PONs), each operating in its native format. A single such fiber plant deployment can support multiple logical PONs, each operating on a unique wavelength pair. This stack of logical PONs can be configured for optimal bandwidth delivery to the end user by controlling the number of optical network units (ONUs) supported in every such logical PON. Microring-resonator-based optical routers are used to dynamically manage the logical network topology to control the number of ONUs supported per logical PON. We present techniques to calculate an optimal network configuration and its use in a typical evolving access scenario. The network view from a data transport perspective and from a control and management perspective is also presented.

A novel ring resonator-based photonic beamformer has been developed for continuous and squint-free control of the reception angle of broadband phased array antenna systems. The core of the system is a ring resonator based optical beamforming network (OBFN) used for delay synchronization and coherent signal combining. The OBFN is integrated in a single chip realized in CMOS-compatible optical waveguide technology together with an optical sideband filter for singlesideband suppressed-carrier modulation, and an optical carrier reinsertion circuit for balanced coherent detection. This paper demonstrates the system functionality by RF-to-RF measurements of the phase and power responses of the integrated OBFN.

A new reverberation chamber with varying angles between wall, floor and ceiling and with vibrating walls is used for in-situ testing of a large radar antenna system. Inside this Vibrating Intrinsic Reverberation Chamber (VIRC) a diffuse, statistically uniform electromagnetic field is created without the use of a mechanical, rotating, mode stirrer. This chamber results in a better homogeneity and increased field strength compared to conventional mode stirred reverberation chambers. The experience gained with this VIRC and results obtained using the VIRC for in-situ electromagnetic interference (EMI) testing will be discussed.

A squint-free, continuously tunable optical beamformer for broadband phased array receive antennas is proposed. The complete system is demonstrated, including E/O and O/E conversions, and optical signal processing. The latter involves delay synchronization and coherent optical combining, which is performed in an integrated ring resonator-based optical beam forming network, realized in low-loss, CMOScompatible TriPleX technology. Successful combination of four beamformer input channels has been demonstrated by means of RF-to-RF measurements.

We present a novel design procedure for optical ring resonator (ORR)-based integrated optical beam forming networks (OBFN) for microwave phased array antenna applications. Given the system specifications of minimum RF signal bandwidth (2.05 GHz), propagation loss in the optical waveguide (0.2 dB/cm) and maximum phase error allowed in band (π/16), the method is used to determine the number of ORRs required in each delay unit for minimum complexity and, in turn, minimum footprint in the realized chip. The effects of the RF phase errors obtained with the described procedure are also analyzed. The result shows negligible degradation in the array radiation pattern when imposing a maximum phase error of π/16 or lower.

A novel squint-free ring resonator-based optical beam forming network (OBFN) for phased array antennas (PAA) is proposed. It is intended to provide broadband connectivity to airborne platforms via geostationary satellites. In this paper, we present the design of the OBFN and its control system. Our goal is to deliver large bandwidth Ku-band connectivity between antennas, mount conformal to the airplane fuselage and on a geostationary satellite, respectively.This way it would be possible to bring live DVB-S television to airplane passengers. In this paper, we present recent research conducted on a 4 × 1 ring resonator-based OBFN test set-up. This OBFN has four optical input ports and one optical output port. It is tuned to provide the desired signal combination with optimal constructive interference between the modulated input signals from the PAA. Therefore, combining circuitry and delay elements are required. The OBFN is tuned by electrically heating tunable true time delay (TTD) elements. These are built using optical ring resonators (ORRs). By cascading multiple ORRs with different resonance frequencies, it is possible to create a TTD with a large bandwidth. Optical beam forming is used because it provides advantages over traditional beam forming methods. These advantages are: large bandwidth, EMI resistance, and, when integrated onto a single chip, compactness and low costs. The OBFN is created using planar optical waveguide technology and consists of the following building blocks: waveguides, Mach-Zehnder interferometers, (MZIs) couplers and ORRs. The tuning of the OBFN is done by an electronic control system using a microcontroller. Communication with a PC is possible using USB. To our knowledge, this is the first integrated ORR-based OBFN circuit for PAA satellite reception.