Unilateral and multi-functional RF front-end filtering networks using spatiotemporally modulated resonators arrays

As wireless networks progress towards the sixth-generation (6G) of wireless, new communication technologies such as massive multiple-input–multiple-output (MIMO), in-band full-duplex (IBFD), and joint communication and sensing (JCAS) are emerging. These technologies impose stringent demands on radio-frequency front-ends (RFFEs) requiring compact, reconfigurable, and multi-functional RF components that can reduce size, weight, power, and cost (SWaP-C) of the RFFE while maintaining high spectral efficiency and adaptability to a wide range of frequency bands, operating conditions, and application scenarios. To address these challenges, this thesis investigates spatiotemporally modulated (STM) resonators as the basis for a new class of RF filtering components and signal-routing networks. The co-designing of RF filters with other front-end functionalities can effectively reduce size and cost. At the same time, the use of STM resonators enables unilateral transmission while remaining low cost, compatible with IC integration and power efficient. First, a transversal STM-resonator architecture is introduced for the realization of bandpass filtering isolators (BPFIs) with high levels of reconfigurability in terms of center frequency, bandwidth (BW), number of passbands, out-of-band suppression and intrinsic switch-off capability. Second, this thesis demonstrates multi-functional STM based devices that integrate variable phase shifting (VP) and variable attenuation (VA) capabilities within the same BPFI structure. They enable unilateral RF signal transmission with continuously phase and attenuation tuning without compromising the transfer function (TF) shape. Finally, the thesis extends the concept to more complex RF front-end architectures by introducing multi-port STM signal-routing networks. Through modulation-state control of the STM resonators, the proposed multi-port RF networks demonstrate versatile RF signal processing functions including RF switching, RF isolation and circulation, and power division with integrated RF filtering functionalities. Overall, this thesis advances the state-of-the-art by introducing three novel STM-resonator-based architectures that, respectively, demonstrate enhanced tunability in unilateral bandpass filtering, the co-integration of filtering with phase and amplitude control, and multi-functional multi-port RF signal routing enabled through modulation state control.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2025

Author dc:creator

• Zhang, Zixiao

Advisor dc:contributor.advisor

• Psychogiou, Dimitra

• Filters
• Non-reciprocal
• Spatiotemporal modulation
• Multi functional circuit
• Full duplex

Statement dc:rights

• © 2025, Zixiao Zhang.

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nc/4.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/18939

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/18939