CORA
Cork Open Research Archive (CORA) is UCC’s Open Access institutional repository which enables UCC researchers to make their research outputs freely available and accessible.
UCC Research Communities
Recent Submissions
Ultra-Compact Inkjet-Printed Folded Waveguide Resonator-Based Bandpass Filters
(Institute of Electrical and Electronics Engineers Inc., 2025-11-19) Dogan, Berkay; Patil, Deepal Deepak; Psychogiou, Dimitra; Taighde Éireann - Research Ireland
A concept to develop ultra-compact self-packaged 3D waveguide bandpass filter (BPF) is reported. It is based on inkjet-printed 3D folded-waveguide resonators. Size compactness is achieved using: i) a miniaturized waveguide resonator geometry and ii) monolithic integration by employing a two-material piezo drop-on-demand process. The operating principles of the folded-waveguide resonator concept are presented using eigenmode simulations while taking into consideration the process manufacturing capabilities. The applicability of the folded waveguide resonator concept to highly-miniaturized monolithic BPF is explored through the design and manufacturing of a second-order BPF that exhibits: i) a passband centred at 10.73 GHz with minimum in-band insertion loss (IL) of 2.65 dB and a 3 dB fractional bandwidth (FBW) of 21.6%. Furthermore, it occupies an ultra-compact volume of only 0.34λ0 x 1.26λ0 x 0.16λ0 and only weighs 1.16 g.
Monolithically-integrated nested ridge waveguide dual-channel filters
(Institute of Electrical and Electronics Engineers Inc., 2025-11-19) Dogan, Berkay; Psychogiou, Dimitra
This paper presents a novel highly-miniaturized dual-channel 3D filter design concept. It is based on a new nested waveguide resonator approach that allows the excitation of two fully-isolated fundamental resonances within the volume of a conventional ridge waveguide. Size compactness is achieved by: i) re-using traditionally unused areas of a ridge waveguide and ii) monolithic integration enabled by stereolithography apparatus 3D printing. A novel ridge-waveguide/waveguide (RW-WG) resonator concept is proposed and analysed in detail for the realization of two-channel filters. For proof-of-concept validation purposes, a dual-channel RW-WG-based bandpass filter (BPF) was designed, manufactured and tested. It exhibits a second order low frequency filtering channel at 6.77 GHz with minimum in-band insertion loss (IL) of 0.16 dB (Qeff of 1,060) and 3 dB fractional bandwidth (FBW) of 7%, and a second order highfrequency filtering channel at 15.39 GHz with minimum IL of 0.2 dB Qeff of 1,365) and 3 dB FBW of 5.3%.
Migration, trade and the Atlantic port cities
(Routledge, 2011) O'Flanagan, Patrick; Hein, Carola
Assessing the impact of energy retrofits on indoor climate conditions using mixed effects models: methodology and R implementation
(Multidisciplinary Digital Publishing Institute (MDPI), 2026-05-29) Mishra, Asit Kumar; European Union’s Horizon 2020 research and innovation programe
Energy retrofit interventions have become increasingly critical as building sectors worldwide pursue decarbonization targets and improved energy efficiency. However, establishing robust causal inference about retrofit impacts on indoor climate conditions remains challenging due to confounding variables including outdoor climate fluctuations and occupant behavior. This paper presents a methodological framework for analyzing pre- and post-retrofit indoor climate data using linear mixed effects (LME) models, which explicitly account for building-level variability while controlling for environmental and behavioral factors. The approach is demonstrated using a case study analyzing partial pressure of water vapor in Irish residential homes before and after energy retrofit interventions. The analysis incorporates standardized coefficients to assess relative importance of predictive factors and employs model parsimony through stepwise removal of non-significant terms. Complete R code is provided to facilitate adaptation by other researchers. Our results demonstrate that LME models provide unbiased estimates of retrofit effects while avoiding aggregation bias that plague simpler analyses. This paper serves as both methodological reference and practical guide for practitioners seeking to rigorously evaluate building retrofit effectiveness across diverse indoor climate parameters.
Ultra-wideband inkjet printed grounded coplanar waveguide-to-folded waveguide transition
(Institute of Electrical and Electronics Engineers Inc., 2026-09-14) Dogan, Berkay; Psychogiou, Dimitra
This paper presents the design and practical development of an ultra-wideband 3D grounded coplanar waveguide (GCPW)-to-folded waveguide (FWG) transition for beamforming antenna systems in X/Ku-band. It is based on a two-stage configuration comprising a three-dimensional (3D) vertical taper transition and a shielded stripline. A novel integration concept using a two-material piezo drop-on-demand process is proposed for ultra-compact 3D monolithic integration. For proof-of-concept validation purposes, a prototype comprising two transitions in a back-to-back configuration was designed and tested. It exhibited a center frequency of 13.3 GHz, a 10-dB return loss (RL) bandwidth (BW) from 9.08 GHz to 17.54 GHz, (i.e., absolute BW of 8.46 GHz) and a fractional BW (FBW) of 63.61%. In this BW, the in-band insertion loss (IL) was measured between 1.05-3.66 dB.