Wideband Low-Cost Smart Passive and Active Integrated Antennas for THz Wireless Communications

Lead Research Organisation: University of Kent
Department Name: Sch of Engineering & Digital Arts

Abstract

WIdeband low-cost Smart passive and active integrateD antennas for thz wireless cOMmunications (WISDOM) proposes a significant advance towards the design and fabrication of smart, wideband and low-cost THz devices. In order to do so, the consortium is built from very complementary expertise with knowledge on 3D printing, antenna, THz circuit and system.
A first key element of WISDOM, is the use of 3D inkjet printing for fast fabrication of THz passive and active antennas. This approach will be combined with THz circuit designs in CMOS. Using multi-material 3D inkjet printing of functional materials to simultaneously deposit conductive and dielectric materials; including thermal and UV rapid solidification of deposited structures, efficient coupling between on-chip signals to free-space radiation will be achieved. This will lead to an important breakthrough that combines two cheap and high-volume technologies, paving a path to consumer-oriented THz products.
A second key element is the combination of the 3D-on-CMOS printing technology with spatial-power combining array antennas, in order to develop highly-efficient THz beams that overcome the increased free-space path loss that prevents THz consumer products today.
In WISDOM, we also plan to demonstrate the concepts with a smart spatial power-combining active array architecture for wideband THz wireless communications. The core WISDOM ICs will be used as active pixels providing spatial power combining with full individual amplitude and phase settings of each pixel in transmit and receive mode. Due to the use of 3D printing (for antennas) and CMOS process (for circuits), it dramatically reduces the cost of THz devices and systems while providing significant advances in THz frontend adaptability. A number of wideband antenna elements, arrays, on-chip active antennas as well as THz front ends circuits (>300 GHz) will be designed, fabricated and measured.

Planned Impact

Academic impact:
The research proposed here will bring different communities, including RF and Microwave devices, THz devices, wireless communications, manufacturing, 3D printing technologies, circuits theory and designs, and wireless systems, together to carry out this pioneering work and the outcomes of this research are likely to have profound impacts across a range of areas in antenna, THz/millimeter-wave front end, wireless systems and 3D Printing technology, and bringing innovations and breakthroughs to current communication and radar technologies.
The results of the proposed project will be conveyed to the beneficiaries and the general public via talks at department seminars (at Warwick, Kent, TU Graz, KULeuven), EPSRC funded CommNet meet-ings and workshops, invited talks at institutes and industries (e.g., IEEE DL talks), and discussions with our industry partners as well as publications in international journals (IEEE T-AP, IEEE Trans on THz Science and Technology, etc) and at major conferences (IRMMW-THz, EuMC, EuCAP, LAPC, IMS) for knowledge dissemination.

People Impacts:
This research will enhance UK's academic standing in the field of THz devices, RF & Microwave Communications, RF & Microwave Devices, 3D Printing and wireless communications, and will contribute to delivering and training highly skilled researchers, ensuring that they develop the skills matched to the demands of their future career paths. The project offers considerable potential for cross training of a new generation of research leaders in the normally separate silos of THz devices, antennas and propagation, 3D printing technologies, and wireless communications and circuits.
A selection of research findings will form part of teaching syllabus for MSc and final year under-graduates as well as for new generation of researchers.

Economic and societal impacts:
Successful exploration of the proposed techniques is likely to provide solutions to future generation of wireless communications which demand significantly higher data rate and capacity. This proposal is timely and expected to contribute to future generation wireless systems, as the use of THz spectrum can solve the problem of spectrum shortage in current wireless communications, broadband satellite communications and radars.
The general public and communication service subscribers will benefit from super-fast broadband multimedia services using THz frequency bands.
The research will facilitate the generation of innovative applications in communication systems, benefits the communications industry with super-fast wireless link and enhances the UK's economic competiveness. The research finds will also be useful for UK national security and defence as the THz smart antennas will be potentially useful for improving the performance of radar imaging significantly.

Publications

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Dong Y (2019) Filtering antennas for energy harvesting in wearable systems in International Journal of Numerical Modelling: Electronic Networks, Devices and Fields

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Gao S (2018) Advanced Antennas for Small Satellites in Proceedings of the IEEE

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Gu C (2017) Dual-Band Electronically Beam-Switched Antenna Using Slot Active Frequency Selective Surface in IEEE Transactions on Antennas and Propagation

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Gu C (2017) Frequency-Agile Beam-Switchable Antenna in IEEE Transactions on Antennas and Propagation

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Hu W (2020) Wideband Circularly Polarized Antenna Using Single-Arm Coupled Asymmetric Dipoles in IEEE Transactions on Antennas and Propagation

 
Description We have completed several novel designs of wideband high-gain antennas around 300 GHz, and also successfully completed the 3D printing manufacturing of the antenna scaled down to 30 GHz. We also completed the novel designs and 3D printed manufacturing of several 140-GHz antennas which achieve good performance in terms of high gain and wide bandwidth. Furthermore, we completed the first design of a 140-GHz antenna with multiple beams, high gain and wide bandwidth. The results have been submitted to IEEE Journals and will be published in the near future. The work led to several invited talks by the PI at international conferences (2020 IEEE iWAT; 2020 EuCAP, etc). In addition, the PI was invited to be in the Expert Group for drafting the 6G White Paper to be published this year.
Exploitation Route the company engineers may use the design techniques we reported in international conferences
Sectors Digital/Communication/Information Technologies (including Software),Electronics

 
Title New method of designing antennas for radar systems 
Description We developed a new method of antenna design for low-sidelobe radar systems. It is a fourth-order filtering patch antenna with a novel coupling structure. Using the proposed coupling structure, both the balanced coupling feed and cross-coupling are realized. Two identical slots etched on the ground plane are utilized to excite the radiating patch with the reduced cross-polarization level. A short slot etched on the ground plane is employed for cross-coupling, which introduces two controllable radiation nulls with a steep roll-off rate. In addition, owing to the split-ring resonators and hairpin resonators, the improved impedance bandwidth is achieved with the fourth-order filtering response. To demonstrate the proposed design techniques, both the filtering antenna element and the low-sidelobe array are designed, fabricated, and measured. The measured results show that the proposed antenna has the impedance bandwidth of 12% (4.78-5.39 GHz) with low profile, the cross-polarization level lower than -31 dB, and two radiation nulls with the suppression higher than 31 dB. For the low-sidelobe antenna array, wide impedance bandwidth is also obtained with the sidelobe level below -28.7 dB, the cross-polarization level below -34 dB, and the out-of-band suppression better than 25 dB. This work is reported in our paper recently published in IEEE Access (L. Wen, S. Gao, Q. Luo, Z. Tang, W. Hu, Y. Yin, Y.L. Geng and Z.Q. Cheng, A balanced feed filtering antenna with novel coupling structure for low-sidelobe radar applications, IEEE Access, Vol. 6, Oct. 2018, pp. 77169 - 77178) 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact We developed a new method of antenna design for low-sidelobe radar systems. It is a fourth-order filtering patch antenna with a novel coupling structure. Using the proposed coupling structure, both the balanced coupling feed and cross-coupling are realized. Two identical slots etched on the ground plane are utilized to excite the radiating patch with the reduced cross-polarization level. A short slot etched on the ground plane is employed for cross-coupling, which introduces two controllable radiation nulls with a steep roll-off rate. In addition, owing to the split-ring resonators and hairpin resonators, the improved impedance bandwidth is achieved with the fourth-order filtering response. To demonstrate the proposed design techniques, both the filtering antenna element and the low-sidelobe array are designed, fabricated, and measured. The measured results show that the proposed antenna has the impedance bandwidth of 12% (4.78-5.39 GHz) with low profile, the cross-polarization level lower than -31 dB, and two radiation nulls with the suppression higher than 31 dB. For the low-sidelobe antenna array, wide impedance bandwidth is also obtained with the sidelobe level below -28.7 dB, the cross-polarization level below -34 dB, and the out-of-band suppression better than 25 dB. This work is reported in our paper recently published in IEEE Access (L. Wen, S. Gao, Q. Luo, Z. Tang, W. Hu, Y. Yin, Y.L. Geng and Z.Q. Cheng, A balanced feed filtering antenna with novel coupling structure for low-sidelobe radar applications, IEEE Access, Vol. 6, Oct. 2018, pp. 77169 - 77178) 
 
Title Novel method of designing compact-size wideband dual-polarized antennas for 4G/5G mobile communications and beyond 
Description We proposed a novel method of antenna design which can enable significant size reduction of antenna size while achieving good performance in terms of wide bandwidth and dual polarization. The design method is called "dual-polarized shared-dipole (DPSD) antenna". Different from the traditional crossed dipole (CD) antennas, the arms of the DPSD antenna are shared for two orthogonal polarizations. This design technique leads to significant size reduction and high isolation compared to the traditional CD antennas. This method is highly innovative and has been reported in our paper recently published in IEEE Transactions on Antennas and Propagation (L. Wen, S. Gao, C. Mao, Q. Luo, W. Hu and Y. Yin, Compact Dual-Polarized Shared-Dipole Antennas for Base Station Applications, IEEE Trans. on Antennas and Propagation, Vol. 66, No. 12, Dec. 2018, pp. 6826 - 6834). This paper has raised lots of interests by people in the UK and internationally, as it has been constantly listed in the most popular articles (the top 50 most frequently accessed documents) in IEEE Trans. on Antennas and Propagation since its publication in Dec. 2018. This method is expected to be employed by antenna engineers for reducing the size of base station antennas in 5G and beyond. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact We proposed a novel method of antenna design which can enable significant size reduction of antenna size while achieving good performance in terms of wide bandwidth and dual polarization. The design method is called "dual-polarized shared-dipole (DPSD) antenna". Different from the traditional crossed dipole (CD) antennas, the arms of the DPSD antenna are shared for two orthogonal polarizations. This design technique leads to significant size reduction and high isolation compared to the traditional CD antennas. This method is highly innovative and has been reported in our paper recently published in IEEE Transactions on Antennas and Propagation (L. Wen, S. Gao, C. Mao, Q. Luo, W. Hu and Y. Yin, Compact Dual-Polarized Shared-Dipole Antennas for Base Station Applications, IEEE Trans. on Antennas and Propagation, Vol. 66, No. 12, Dec. 2018, pp. 6826 - 6834). This paper has raised lots of interests by people in the UK and internationally, as it has been constantly listed in the most popular articles (the top 50 most frequently accessed documents) in IEEE Trans. on Antennas and Propagation since its publication in Dec. 2018. This method is expected to be employed by antenna engineers for reducing the size of base station antennas in 5G and beyond. 
URL https://ieeexplore.ieee.org/document/8470132
 
Title Novel method of designing ultra-wideband reflectarray antennas for satellite communications 
Description We developed a novel method of designing ultra-wide-band reflectarray antennas for applications in satellite communications. It is called "tightly coupled dipole reflectarray (TCDR) antenna". Traditionally, reflectarray antenna has the limitation of narrow bandwidth which seriously limits its applications into wireless systems which typically require broad bandwidth or ultra-wideband performance. To overcome this limitation, we proposed this method of designing TCDR antenna. This reflectarray antenna consists of a wideband feed and a wideband reflecting surface. The feed is a log-periodic dipole array antenna. The reflecting surface consists of 26 × 11 unit cells. Each cell is composed of a tightly coupled dipole and a delay line. The minimum distance between adjacent cells is 8 mm, which is about 1/10 wavelength at the lowest operating frequency. By combining the advantages of reflectarray antennas and those of tightly coupled array antennas, the proposed TCDR antenna achieves ultrawide bandwidth with reduced complexity and fabrication cost. A method to minimize the phase errors of the wideband reflectarray is also developed and the concept of equivalent distance delay is introduced to design the unit cell elements. To verify the design concept, a prototype operating from 3.4 to 10.6 GHz is simulated and fabricated. Good agreement between simulated and measured results is observed. Within the designed frequency band, the radiation pattern of the TCDR antenna is stable and the main beam of the antenna is not distorted or split. The side lobe levels of the radiation patterns are below -11.7 dB in the entire operating band. It is the first time a tightly coupled reflectarray is reported. The method has been reported in our paper recently published in IEEE Transactions on Antennas and Propagation (W. Li, S. Gao, Q. Luo, L. Zhang and Y.M. Cai, An Ultra-wide-band Tightly Coupled Dipole Reflectarray Antenna, IEEE Trans. on Antennas and Propagation, Feb. 2018, pp. 533-540). This paper was listed as the first paper in that issue published. After the paper is published, we have received lots of enquiries regarding this method as the community is very interested in such a method. I was also invited to present this work to industries in the UK and Europe during recent months and many people showed great interest in this work. The paper is published in IEEE as open access. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact We developed a novel method of designing ultra-wide-band reflectarray antennas for applications in satellite communications. It is called "tightly coupled dipole reflectarray (TCDR) antenna". Traditionally, reflectarray antenna has the limitation of narrow bandwidth which seriously limits its applications into wireless systems which typically require broad bandwidth or ultra-wideband performance. To overcome this limitation, we proposed this method of designing TCDR antenna. This reflectarray antenna consists of a wideband feed and a wideband reflecting surface. The feed is a log-periodic dipole array antenna. The reflecting surface consists of 26 × 11 unit cells. Each cell is composed of a tightly coupled dipole and a delay line. The minimum distance between adjacent cells is 8 mm, which is about 1/10 wavelength at the lowest operating frequency. By combining the advantages of reflectarray antennas and those of tightly coupled array antennas, the proposed TCDR antenna achieves ultrawide bandwidth with reduced complexity and fabrication cost. A method to minimize the phase errors of the wideband reflectarray is also developed and the concept of equivalent distance delay is introduced to design the unit cell elements. To verify the design concept, a prototype operating from 3.4 to 10.6 GHz is simulated and fabricated. Good agreement between simulated and measured results is observed. Within the designed frequency band, the radiation pattern of the TCDR antenna is stable and the main beam of the antenna is not distorted or split. The side lobe levels of the radiation patterns are below -11.7 dB in the entire operating band. It is the first time a tightly coupled reflectarray is reported. The method has been reported in our paper recently published in IEEE Transactions on Antennas and Propagation (W. Li, S. Gao, Q. Luo, L. Zhang and Y.M. Cai, An Ultra-wide-band Tightly Coupled Dipole Reflectarray Antenna, IEEE Trans. on Antennas and Propagation, Feb. 2018, pp. 533-540). This paper was listed as the first paper in that issue published. After the paper is published, we have received lots of enquiries regarding this method as the community is very interested in such a method. I was also invited to present this work to industries in the UK and Europe during recent months and many people showed great interest in this work. The paper is published in IEEE as open access. 
URL https://ieeexplore.ieee.org/document/8186260
 
Title new design technique of wideband compact-size antenna with circular polarization and low profile 
Description A novel method of designing a wideband series-fed circularly polarized (CP) differential antenna by using crossed open slot pairs is proposed. The near-field distributions and input impedance analyses show that the closely spaced open slot-pairs can radiate as the crossed dipoles and have stable radiating resistance with a compact radiator size. Besides, a wideband half-power phase shifter using open slot is proposed and utilized to realize CP radiation. The proposed CP antenna is composed of a wide slot-pair and a narrow slot-pair. In the antenna design, the narrow slot-pair is not only excited as a radiator, but also elaborately loaded to provide wideband half-power output and quadrature phase excitation to the wide slot-pair. Both the proposed half-power phase shifter and CP antenna are illustrated by the corresponding equivalent circuits. Based on these analyses, the proposed antenna is designed, fabricated, and measured. Compared with the simulated traditionally designed counterpart, 2.1 times wider axial ratio (AR) bandwidth is achieved for the proposed antenna. The measured overlapped bandwidth for AR <; 3 dB and return loss >10 dB is 1.95-3.45 GHz (55.6%). Also, the antenna gain and radiation patterns are measured, which agree well with the simulated results 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact The novel design technique will be promising for applications in Global Navigation Satellite Systems (GNSS) and satellite communications. For GNSS systems, they require a compact-size CP antenna with wide bandwidth so as to cover multiple frequency bands in GNSS, and the proposed antenna will be very suitable for such applications. 
URL https://ieeexplore.ieee.org/document/8936548
 
Title new design techqniue for wideband circularly-polarized antenna 
Description We proposed a novel design concept to realize a wideband circularly polarized (CP) antenna by using single-arm coupled asymmetric dipoles (SCADs). First, an impedance compensation method is developed to obtain flat antenna input impedance by designing different arm lengths of the asymmetric dipole. Then, a single-arm coupling method is introduced to improve the antenna bandwidth. Four asymmetric dipoles are bent and sequentially coupled to each other among the long arms of the dipoles. By elaborately adjusting the coupling among the long arms, improved bandwidth and compact radiator size are achieved simultaneously. In addition, to further enhance and optimize the operating bandwidth of the antenna implementation, impedance matching strip and interdigital structure are introduced into SCADs. To verify the design concept, a prototype of the SCAD antenna was designed, fabricated, and measured. Experimental results agree well with the simulations, showing a wide impedance bandwidth of 108% (1.53-5.12 GHz) and an axial ratio (AR) bandwidth of 96% (1.78-5.06 GHz). To the best of our knowledge, the proposed design concept of SCADs is first used to design a wideband CP antenna. Both the simulated and measured results prove that the proposed antenna is a promising candidate for modern broadband CP applications. 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact This design technique is very promising for applications in GNSS and satellite communications systems. 
URL https://ieeexplore.ieee.org/document/9014502
 
Title new method of designing multi-beam antennas for autonomous vehicles 
Description We developed a new method of designing multibeam dual-circularly polarized (CP) reflectarray antenna for connected and autonomous vehicles. The developed reflectarray uses one aperture to realize dualband and multibeam operation. At each frequency band, there are two simultaneously shaped beams with different circular polarizations. Totally four beams are obtained with a single feed and each of the beams can be independently controlled. A simple but effective polarization suppression technique is introduced to suppress cross polarizations at large scan angles so the CP beam of the reflectarray can be configured to point at large angles. Thus, the present reflectarray is suitable to be applied to vehicles for reliable high data-rate satellite communications. To validate the design concept, an X-band prototype was designed, fabricated and measured. The design concept is flexible and can be applied to the design of dual-band, dual-CP reflectarray with different frequencies ratios. Moreover, the present design can also be extended to a continuous beam-steering design by incorporating phase shifters. This work has been accepted for publication in IEEE Transactions on Vehicular Technology (14. Q. Luo, S. Gao, W. Li, M. Soby, B. Hayden, I.M. Reaney and X.X. Yang, Multibeam Dual-Circularly Polarized Reflectarray for Connected and Autonomous Vehicles, IEEE Trans. on Vehicular Technology, 2019, accepted, early access) 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? Yes  
Impact We developed a new method of designing multibeam dual-circularly polarized (CP) reflectarray antenna for connected and autonomous vehicles. The developed reflectarray uses one aperture to realize dualband and multibeam operation. At each frequency band, there are two simultaneously shaped beams with different circular polarizations. Totally four beams are obtained with a single feed and each of the beams can be independently controlled. A simple but effective polarization suppression technique is introduced to suppress cross polarizations at large scan angles so the CP beam of the reflectarray can be configured to point at large angles. Thus, the present reflectarray is suitable to be applied to vehicles for reliable high data-rate satellite communications. To validate the design concept, an X-band prototype was designed, fabricated and measured. The design concept is flexible and can be applied to the design of dual-band, dual-CP reflectarray with different frequencies ratios. Moreover, the present design can also be extended to a continuous beam-steering design by incorporating phase shifters. This work has been accepted for publication in IEEE Transactions on Vehicular Technology (14. Q. Luo, S. Gao, W. Li, M. Soby, B. Hayden, I.M. Reaney and X.X. Yang, Multibeam Dual-Circularly Polarized Reflectarray for Connected and Autonomous Vehicles, IEEE Trans. on Vehicular Technology, 2019, accepted, early access) 
URL https://ieeexplore.ieee.org/document/8633341
 
Title new technique for designing antenna with Wideband Dual Circular Polarization 
Description A novel wideband dual circularly polarized (DCP) antenna is proposed and developed for intelligent transport system (ITS) applications, which can be used to improve the receiver sensitivity and communication quality of ITS. The proposed DCP antenna is composed of an orthogonal power divider (OPD) with two orthogonal input ports, four phase shifters for quadrature phase output, and four crossed dipoles for DCP radiation. Detailed equivalent circuit analysis shows that the OPD has two orthogonal inputs and four equal magnitude in-phase and out-of-phase outputs. To achieve two sets of orthogonal quadrature output signals for DCP radiation, the lumped element based differential right-hand transmission line unit cell and left-hand transmission line unit cell are elaborately introduced as the ±45° phase shifters, and incorporated into the OPD. Eventually, orthogonal quadrature signals are successfully obtained and fed to the crossed dipoles for DCP radiation. The proposed antenna was then designed, fabricated, and measured for ITS applications. The measured results show that the overlapped impedance bandwidth of both two input ports is 1.07-1.85 GHz (53.4%), and the isolation is higher than 15.2 dB. Moreover, low axial ratio (<; 1.7 dB) and symmetrical radiation patterns are achieved for unidirectional DCP radiation 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact The wideband dual circularly polarized (DCP) antenna proposed is very promising for applications in intelligent transport system (ITS) and smart cities as it can be used to significantly improve the receiver sensitivity and communication quality of ITS. This will enable the improvement of road safety 
URL https://ieeexplore.ieee.org/document/9034194
 
Title new technique of design wideband high-efficiency circularly polarized antenna at millimeter-wave and THz frequencies 
Description We proposed a wideband high-efficiency millimeter-wave (mm-wave) circularly polarized (CP) array which is constituted by novel planar substrate integrated waveguide (SIW)-fed S-dipoles. The proposed mm-wave CP S-dipole consists of two rotational symmetric curved arms and is fed differentially through aperture coupling, which features simple configuration and excellent performance. Detailed analysis is given to explain the operating principles of this element. It is noted that superior element performance including a wide impedance bandwidth of 43%, a wide 3 dB axial ratio (AR) bandwidth of 36%, and 1 dB gain bandwidth of 38% is achieved by the planar SIW-fed S-dipole. By feeding 64 in-phase S-dipole elements through a full-corporate SIW feeding network, a planar wideband highly efficient mm-wave 8×8 CP array is realized. To verify the design concept, a prototype operating at Ka-band is fabricated and measured. The measurement results indicate that the proposed array achieves a wide overlapped bandwidth of 27.6%, a high antenna gain of 25.2 dBic, and a high aperture efficiency of 89.9%. Attributed to the planar and robust array structure as well as its excellent performance, the presented array is a good candidate for various mm-wave applications. It is also promising for THz system applications 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact The proposed antenna has advantage of having a planar and robust array structure as well as its excellent performance. It is a good candidate for applications in wireless communication systems at mm-wave and THz frequencies 
URL https://ieeexplore.ieee.org/document/8839704
 
Title new technique of designing dual-polarized cross-slot array antenna at millimeter-wave and sub-THz frequencies 
Description We developed a novel technique of designing dual-polarized crossed slot planar array antenna. The proposed design integrates the antenna array with the feeding networks on a single laminate. The antenna element is developed by using a TE210 and TE120 mode cavity, which is constructed by inserting a number of metalized posts around the crossed region of two perpendicular substrate integrated waveguides (SIWs). The crossed slot is etched over the cavity and is excited from two orthogonal directions to realize dual-polarization. Owing to the orthogonality between the TE210 and TE120 mode, high isolation and low cross-polarization are achieved. A prototype of the designed antenna array operating at 25 GHz is fabricated and measured. The measured results confirm that the presented array antenna has high port isolation (>41 dB), high cross-polarization discrimination (XPD) (>26 dB), and high aperture efficiency (40%). Compared to the state of the art, the proposed design has advantages of simple configuration, easy manufacturing, low cost, good radiation performance, and high efficiency, and this proposed array antenna is promising for applications in high-speed wireless communications at millimeter-wave and sub-THz frequencies 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact Compared to the state of the art development, the proposed antenna design has advantages of simple configuration, easy manufacturing, low cost, good radiation performance, high isolation and high efficiency. In addition, this proposed array antenna is promising for applications in high-speed wireless communications at millimeter-wave and sub-THz frequencies (6G, etc) 
URL https://ieeexplore.ieee.org/document/8917812
 
Title new technique of designing ultra-wideband circularly-polarized array antenna and the theoretical analysis 
Description We proposed the novel design and analysis of an ultrawideband (UWB) circularly polarized (CP) antenna element and its array. First, an UWB CP antenna element using circular-arc-shaped monopole (CASM) with asymmetric ground plane is proposed. Characteristic mode analysis (CMA) is used to investigate its CP operating mechanism, providing physical insights into different modes (mode currents and characteristic radiation fields) at various frequencies. The CMA results show that the asymmetric ground plane makes great contribution to produce CP radiation in the lower frequency band, while another upper CP band is generated by CASM. Thus, the overall 3 dB axial ratio bandwidth (ARBW) of the element can be significantly expanded. Furthermore, a 2×2 UWB CP array is designed based on this element. A gradient artificial magnetic conductor (GAMC) with a metal cone is adopted to realize both a low-profile ( 0.1×? , where ? is the air-free wavelength at lowest frequency) and the high-gain radiation for the first time. To validate this novel configuration, this array is fabricated and measured. The measured bandwidth ( |S 11 |<-10 dB, AR < 3 dB) is approximately 92.3% (1.75-4.75 GHz). It also achieves a wide 3 dB gain bandwidth of 72.3%. Both the simulated and measured results demonstrate that this low-profile high-gain antenna array is promising for applications in wireless systems such as mobile satellite communication system 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact This antenna design has advantages of low profile, high gain, ultra-wideband performance and circular polarization, thus it is promising for applications in wireless systems such as mobile satellite communication system and GNSS 
URL https://ieeexplore.ieee.org/document/9109654
 
Title new techniques of antenna manufacturing, design and measurements at sub-THz frequencies 
Description We developed new techniques of design, manufacturing and measurements of antennas at sub-THz frequencies such as D band. The antenna employs an all-metal structure and is based on the resonant cavity antenna (RCA) concept. A novel impedance matching technique is introduced to broaden the antenna return loss bandwidth. Two gain enhancement methods have been employed to achieve a more directive beam with reduced side lobes and back lobes. The D-band antenna prototypes are produced using i) all-metal printing without any postprocessing; ii) dielectric printing with copper metallization applied later. Comparisons of the simulated and measured results amongst the antennas fabricated using the two additive manufacturing techniques are made. Measurement results of the two antenna prototypes show that the proposed design can achieve a 14.2% bandwidth with a maximum gain of 15.5 dBi at 135 GHz. This work is the first D-band resonant cavity antenna fabricated using two different 3D printing methods 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact The techniques will enable the development of high-performance antennas at sub-THz frequencies. Such antenna technologies will be important for the future generation (6G) of mobile communications. 
URL https://ieeexplore.ieee.org/document/9064607
 
Description Invited talk at 2019 European Conference on Antennas and Propagation, 2019, Poland 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact I was invited to give a talk on our research results funded from this grant. The talk was very successful and the audiences including academics and industries internationally expressed strong interests in our work. The web link is https://ieeexplore.ieee.org/document/8740015
Year(s) Of Engagement Activity 2019
URL https://www.eucap2019.org/
 
Description Invited talk at 2019 IEEE International Wireless Symposium, May 2019, Guangzhou, China 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact My team presented several talks, including one invited talk, this international symposium. One of our paper was shortlisted for the Best Paper Award at this symposium. The web link is http://www.em-conf.com/iws2019/
Year(s) Of Engagement Activity 2019
URL http://www.em-conf.com/iws2019/
 
Description Invited talk at 2020 Asia Pacific Microwave Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I was invited to give an invited talk at 2020 Asia Pacific Microwave Conference, organized by City University Hong Kong. This is one of largest international conference in areas of antennas, electromagnetics, RF and microwave and THz. Over 1000 people attended this conference. Due to pandemic, this conference was held virtually and I gave the talk via Zooms.
Year(s) Of Engagement Activity 2020
URL http://www.ee.cityu.edu.hk/skltmw/apmc2020/index.php
 
Description Invited talk at 2020 International Conference on Microwave and Millimeter Wave Technology(ICMMT2020) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I was invited to give an invited talk at 2020 International Conference on Microwave and Millimeter Wave Technology(ICMMT2020. This is a large international conference in fields of RF, Microwave and Millimeter Wave Technology. The conference was held virtually and I was giving the talk via Zooms
Year(s) Of Engagement Activity 2020
URL http://www.cnmw.cn/mwie2020/en_icmmt2020.html
 
Description Invited talks at 2019 International Symposium on Antennas and Propagation, 2019, Xi'an, China 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact My team gave several talks, including one invited talk from myself, at 2019 International Symposium on Antennas and Propagation (ISAP), Oct. 2019, Xi'an, China. One of our papers won the Best Paper Award at this international conference. The web link is http://www.em-conf.com/isap2019/
Year(s) Of Engagement Activity 2019
URL http://www.em-conf.com/isap2019/
 
Description Invited talks at IET Workshop on Antennas and Propagation for 5G and beyond 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Three invited talks (Mr. L.H. Wen, Mr. Q. Yang and Mr. W. Hu) from my team are presented at 2019 IET Workshop on Antennas and Propagation for 5G and beyond, which takes place at Birmingham, on Feb. 28, 2019. The audiences include researchers in the field of antennas and propagation, engineers from commercial companies from the UK and internationally, research students, academics, some policymakers, etc. In total there are 13 invited talks from various institutes in the UK and internationally, but 3 invited talks are from my team at the University of Kent ((Mr. L.H. Wen, Mr. Q. Yang and Mr. W. Hu). These clearly demonstrate the significant strength of our research team in the field of antennas and propagation, as a result of funding support from EPSRC grant. The titles of three invited talks from my team include: 1) Design of Dual-Band Compact Terminal Antenna Inspired by Composite RightLeft-Handed Transmission Line (Mr Wei Hu); 2)Wideband and Compact Dual-Polarized Antennas for Base Station Applications; 3) Compact Butler Matrix Multibeam Network for 5G Communications
Year(s) Of Engagement Activity 2019
URL https://events2.theiet.org/antennas/programme.cfm
 
Description Two invited talks in international conference 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Two invited talks were presented by my team members at European Conference on Antennas and Propagation, London, March 2018 (2018 EuCAP), a leading conference in the field of antennas and propagation. The talks raised lots of questions and interests from audiences who are researchers, engineers, research students and academics from the UK and internationally. The two invited talks include:
1. Q. Luo, S. Gao, et al., GaN-integrated beam-switching high-power active array for satellite communications, EuCAP 2018, March 2018, UK (Invited)
2.C. Gu, S. Gao, B. Sanz, E. Parker, G.Y. Wen and Z.Q. Cheng, Frequency-reconfigurable pattern-steerable antenna using active frequency selective surfaces, EuCAP 2018, March 2018, UK (Invited)
Year(s) Of Engagement Activity 2018
URL https://www.eucap2018.org/
 
Description invited talk at 2020 Asia Pacific Conference on Antennas and Propagation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I was invited to give a talk at 2020 Asia Pacific Conference on Antennas and Propagation. The topic of my talk is about "Sub-THz and Millimeter-wave Antennas for Next-Generation 6G Wireless Communications". This is one of largest conference in areas of antennas and propagation, electromagnetic field theory and applications. It was attended by over 1000 people. Due to pandemic, it was held virtually, and I gave the talk via Zooms.
Year(s) Of Engagement Activity 2020
URL http://www.em-conf.com/apcap2020/