106 - Beamforming user antenna for wideband radionavigation signals in C-band​

The rapid increase in GNSS RFI (e.g., in Baltic and Scandinavian peninsula there were 122 days with GPS jamming in 2022, and 294 days in 2023) is staggering. Accordingly, in recent years, beamforming techniques have been deployed in GNSS receivers (in the L-band) either to provide a spatial filter or to improve the signal-to-noise-power (CN0) level.  

Beamforming techniques can achieve a directional pattern performance towards a desired location by varying the phase and amplitude of every individual antenna’s weight. Therefore, the main lobe of the array pattern can be steered towards the desired direction without physically moving the antennas. Furthermore, array antennas can be utilized as a spatial filter; i.e. the null regions of the array antenna pattern can be steered towards the undesired directions (e.g. directions where there are jammers/spoofers, interference, noise sources, etc), consequently achieving a high CN0 to the desired signals.

With the introduction of the “new space” paradigm, the C-band for satellite-based PNT systems attracts a significant attention. Companies such as Xona Space and Trustpoint, are deploying it in the new satellites’ constellations. Furthermore, some new RF frontend devices have been introduced that are able to provide multiple RF-chains with a wide bandwidth in the C-band, e.g, USRP x410 (30k€ euros) provides 4Rx and 4Tx channels with a bandwidth up to 400 MHz per channel. 

Finally, the C-band navigation signals have a great interest for the automotive sector due to the large operational bandwidth and the foreseen high positioning accuracy. Accordingly, providing a beamforming receiver, in the C-band, will increase the positioning accuracy, reliability and resiliency against multipath, jamming and spoofing.

The objective of this activity is to design, develop, and validate a beamforming navigation receiver in C-band RF spectrum. The proposed system should be able to provide the following:

• Beamforming the main lobe towards the LEO satellites, steering it as fast as required by their very high relative velocity
• Providing a spatial filter to mitigate the jamming and spoofing attacks
• Capable of acquiring and decoding live LEO-PNT signals
• Consider the spatial movement of the receiver to represent mobile receivers in vehicles.  

The tasks to be performed shall include:
 

• study, design, and demonstrate the deployment of C-band beamforming antenna 
• include the ability to receive a very large bandwidth in the C frequency band (up to 240 MHz, according to potential evolutions in ITU)
• ensure a high phase stability among the RF-chains and the entire bandwidth
• include high gain dual polarization antenna elements that have a stable pattern response over the wide bandwidth
• optimize the antennas’ placement to provide accurate beamforming response over the large bandwidth.

The main outputs of the activity will consist of:

• Survey of state of the art on array antennas for the wideband signal processing in the C-band 
• beamforming navigation receiver (compact hardware and software) and verification and validation test report