Development of a broadband and squint-free Ku-band phased array antenna system for airborne satellite communications

Novel avionic communication systems are required for various purposes, for example to increase the flight safety and operational integrity as well as to enhance the quality of service to passengers on board. To serve these purposes, a key technology that is essential to be developed is an antenna system that can provide broadband connectivity within aircraft cabins at an affordable price. Currently, in the European Commission (EC) 7th Framework Programme SANDRA project (SANDRA, 2011), a development of such an antenna system is being carried out. The system is an electronically-steered phased-array antenna (PAA) with a low aerodynamic profile. The reception of digital video broadcasting by satellite (DVB-S) signal which is in the frequency range of 10.7-12.75 GHz (Ku-band) is being considered. In order to ensure the quality of service provided to the passengers, the developed antenna should be able to receive the entire DVB-S band at once while complying with the requirements of the DVB-S system (Morello & Mignone, 2006). These requirements, as will be explained later, dictate a broadband antenna system where the beam is squint-free, i.e. no variation of beam pointing direction for all the frequencies in the desired band. Additionally, to track the satellite, the seamless tunability of the beam pointing direction of this antenna is also required. In this work, a concept of optical beamforming (Riza & Thompson, 1997) is implemented to provide a squint-free beam over the entire Ku-band for all the desired pointing directions. The optical beamformer itself consists of continuously tunable optical delay lines that enable seamless tunability of the beam pointing direction

Continuously tunable photonic fractional Hilbert transformer using ring resonators for on-chip microwave photonic signal processing

We propose and demonstrate a wideband photonic fractional Hilbert transformer implemented using a ring resonator-based optical all-pass filter. The full programmability of the ring resonators allows variable and arbitrary fractional order of the Hilbert transformer. The implemented all-pass filter performs a good approximation to the ideal Hilbert transform response, and it can be used as a building block to construct onchip complex microwave photonic signal processors

Continuously tunable photonic fractional Hilbert transformer using ring resonators for on-chip microwave photonic signal processing

We propose and demonstrate a wideband photonic fractional Hilbert transformer implemented using a ring resonator-based optical all-pass filter. The full programmability of the ring resonators allows variable and arbitrary fractional order of the Hilbert transformer. The implemented all-pass filter performs a good approximation to the ideal Hilbert transform response, and it can be used as a building block to construct onchip complex microwave photonic signal processors

Measuring particle size distributions via the polarization dependence of second harmonic generation

We present a method to determine particle size distributions in powders, based on the polarization dependent second harmonic generation (SHG). Unlike existing methods, dilution is not required and is largely insensitive to the optical alignment