This paper proposes a stable gain and a compact Antipodal Vivaldi Antenna(AVA)for a 38GHz band of 5G communication.A novel compact AVA is designed to provide constant gain,high front to back ratio(FBR),and very high e...This paper proposes a stable gain and a compact Antipodal Vivaldi Antenna(AVA)for a 38GHz band of 5G communication.A novel compact AVA is designed to provide constant gain,high front to back ratio(FBR),and very high efficiency.The performance of the proposed AVA is enhanced with the help of a dielectric lens(DL)and corrugations.A rectangular-shaped DL is incorporated in conventional AVA(CAVA)to enhance its gain up to 1 dBi and the bandwidth by 1.8 GHz.Next,the rectangular corrugations are implemented in CAVA with lens(CAVA-L)to further improve the gain and bandwidth.The proposed AVA with lens and corrugations(AVA-LC)gives a constant and high gain of 8.2 to 9 dBi.The designed AVA-LC operates from 34 to 45GHz frequency which covers 38GHz(37.5 to 43.5 GHz)band of 5G applications.Further,the presented AVA-LC mitigates the back lobe and sidelobe levels,resulting in FBR and efficiency improvement.The FBR is in the range of 12.2 to 22 dB,and efficiency is 99%,almost constant.The AVA-LC is fabricated on Roger’s RT/duroid 5880 substrate,and it is tested to verify the simulated results.The proposed compact AVA-LC with high gain,an improved FBR,excellent efficiency,and stable radiation patterns is suitable for the 38GHz band of 5G devices.展开更多
Approaching the distance of 180°, seismic focusing greatly amplifies the normally weak PKIIKP phase(underside reflection from the inner core boundary). Anomalously strong amplitudes of the PKIIKP phase reported p...Approaching the distance of 180°, seismic focusing greatly amplifies the normally weak PKIIKP phase(underside reflection from the inner core boundary). Anomalously strong amplitudes of the PKIIKP phase reported previously at near antipodal distances(at seismic station TAM in North Africa) have been interpreted to infer anomalous structure(s) of the inner core boundary(including a sharp drop of compressional wave speed in the bottommost outer core or a near-zero shear wave speed in the topmost inner core). However,our observations of 12 earthquakes located antipodal to TAM(including the previously cited four events) suggest, for several reasons,that the anomalous PKIIKP energy might be a seismic phase misidentification. The anomalous phase appeared at distances less than 179.6° but not at larger distances(～179.8°). The phase appears consistently from antipode to distances less than 160° and has horizontal slowness similar to the PKIKP phase(going straight through the inner core). Its travel times vary greatly and show a systematic difference between two groups of events at different distances. A simple point scatter provides a good match to the travel times and the systematic variation of the anomalous phase at most stations, suggesting that it could originate from scattering off strong heterogeneities in the mantle wedge above the subducting Tonga slab. The phase misidentification suggests that the previously proposed inner core boundary structure(s) based on the anomalous phase need to be re-evaluated.展开更多
This paper presents the design and analysis of antipodal Vivaldi antennas(AVAs)for breast cancer detection.In order to enhance the antenna gain,different techniques such as using the uniform and non-uniform corrugatio...This paper presents the design and analysis of antipodal Vivaldi antennas(AVAs)for breast cancer detection.In order to enhance the antenna gain,different techniques such as using the uniform and non-uniform corrugation,expanding the dielectric substrate and adding the parasitic patch are applied to original AVA.The design procedure of two developed AVA structures i.e.,AVA with non-uniform corrugation and AVA with parasitic patch are presented.The proposed AVAs are designed on inexpensive FR4 substrate.The AVA with non-uniform corrugation has compact dimension of 50×50 mm2 or 0.28λL×0.28λL,whereλL is wavelength of the lowest operating frequency.The antenna can operate within the frequency range from 1.63 GHz to over 8 GHz.For the AVA with parasitic patch and uniform corrugation,the overall size of antenna is 50×86 mm2 or 0.24λL×0.41λL.It can operate within the frequency range from 1.4 GHz to over 8 GHz.The maximum gain for AVA with non-uniform corrugation and AVA with parasitic patch and uniform corrugation are 9.03 and 11.31 dBi,respectively.The corrugation profile and parasitic patch of the proposed antenna are optimized to achieve the desired properties for breast cancer detection.In addition,the proposed AVAs are measured with breast phantom to detect cancerous cell inside the breast and the performance in detecting cancerous cell are discussed.The measured result can confirm that the proposed AVAs can detect unwanted cell inside the breast while maintaining the compact size,simple structure and low complexity in design.展开更多
The great Lisbon earthquake Nov.1,1755 devastated the city and Portuguese coastlines down to Morocco.Many details of the event are typical signs of chaotic terrane caused by an antipodal impact.A faint but fresh-looki...The great Lisbon earthquake Nov.1,1755 devastated the city and Portuguese coastlines down to Morocco.Many details of the event are typical signs of chaotic terrane caused by an antipodal impact.A faint but fresh-looking antipodal impact structure centered at 35°39′S,168°26′E is found in the Tasman Sea,or about 405 km WSW(West-Southwest)of Cape Reinga,North Island,NZ(North Island).By conventional geological methods,the epicenter has been inferred to be on the bottom of the Atlantic Ocean,in an area known as the Horseshoe Plain WSW of Cape St.Vincent,Portugal,at a distance of about 200 km from the cape,a round figure estimate.The impact antipode at 35°39′N,11°34′W also is located in the Horseshoe Plain at 277 km WSW of Cape St.Vincent,the implied antipodal impact quake epicenter.展开更多
本文研究了 W 波段对脊鳍线过渡的波导—微带转换技术,对余弦平方渐变和 Spline 曲线渐变两种形式的对脊鳍线过渡进行了分析和仿真,并设计制作了 Spline 曲线形式的波导-对脊鳍线-微带转换,结构为背靠背。在整个 W 波段,单个过渡结构插...本文研究了 W 波段对脊鳍线过渡的波导—微带转换技术,对余弦平方渐变和 Spline 曲线渐变两种形式的对脊鳍线过渡进行了分析和仿真,并设计制作了 Spline 曲线形式的波导-对脊鳍线-微带转换,结构为背靠背。在整个 W 波段,单个过渡结构插入损耗小于1.3dB,回波损耗小于-13dB,在（90～99）GHz 内,单个过渡结构插入损耗小于1.0dB,回波损耗小于-20dB,实现了很好的宽带过渡性能。展开更多
基金This research was funded by Princess Nourah bint Abdulrahman University Researchers Supporting Project number(PNURSP2022R79)Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabia,S.Urooj,www.pnu.edu.sa.
文摘This paper proposes a stable gain and a compact Antipodal Vivaldi Antenna(AVA)for a 38GHz band of 5G communication.A novel compact AVA is designed to provide constant gain,high front to back ratio(FBR),and very high efficiency.The performance of the proposed AVA is enhanced with the help of a dielectric lens(DL)and corrugations.A rectangular-shaped DL is incorporated in conventional AVA(CAVA)to enhance its gain up to 1 dBi and the bandwidth by 1.8 GHz.Next,the rectangular corrugations are implemented in CAVA with lens(CAVA-L)to further improve the gain and bandwidth.The proposed AVA with lens and corrugations(AVA-LC)gives a constant and high gain of 8.2 to 9 dBi.The designed AVA-LC operates from 34 to 45GHz frequency which covers 38GHz(37.5 to 43.5 GHz)band of 5G applications.Further,the presented AVA-LC mitigates the back lobe and sidelobe levels,resulting in FBR and efficiency improvement.The FBR is in the range of 12.2 to 22 dB,and efficiency is 99%,almost constant.The AVA-LC is fabricated on Roger’s RT/duroid 5880 substrate,and it is tested to verify the simulated results.The proposed compact AVA-LC with high gain,an improved FBR,excellent efficiency,and stable radiation patterns is suitable for the 38GHz band of 5G devices.
基金supported by National Science Foundation of China(41774056)the US Nationa Science Foundation(EAR 1620595)
文摘Approaching the distance of 180°, seismic focusing greatly amplifies the normally weak PKIIKP phase(underside reflection from the inner core boundary). Anomalously strong amplitudes of the PKIIKP phase reported previously at near antipodal distances(at seismic station TAM in North Africa) have been interpreted to infer anomalous structure(s) of the inner core boundary(including a sharp drop of compressional wave speed in the bottommost outer core or a near-zero shear wave speed in the topmost inner core). However,our observations of 12 earthquakes located antipodal to TAM(including the previously cited four events) suggest, for several reasons,that the anomalous PKIIKP energy might be a seismic phase misidentification. The anomalous phase appeared at distances less than 179.6° but not at larger distances(～179.8°). The phase appears consistently from antipode to distances less than 160° and has horizontal slowness similar to the PKIKP phase(going straight through the inner core). Its travel times vary greatly and show a systematic difference between two groups of events at different distances. A simple point scatter provides a good match to the travel times and the systematic variation of the anomalous phase at most stations, suggesting that it could originate from scattering off strong heterogeneities in the mantle wedge above the subducting Tonga slab. The phase misidentification suggests that the previously proposed inner core boundary structure(s) based on the anomalous phase need to be re-evaluated.
基金This research was funded by National Science,Research and Innovation Fund(NSRF)King Mongkut’s University of Technology North Bangkok with Contract no.KMUTNB-FF-65–07.
文摘This paper presents the design and analysis of antipodal Vivaldi antennas(AVAs)for breast cancer detection.In order to enhance the antenna gain,different techniques such as using the uniform and non-uniform corrugation,expanding the dielectric substrate and adding the parasitic patch are applied to original AVA.The design procedure of two developed AVA structures i.e.,AVA with non-uniform corrugation and AVA with parasitic patch are presented.The proposed AVAs are designed on inexpensive FR4 substrate.The AVA with non-uniform corrugation has compact dimension of 50×50 mm2 or 0.28λL×0.28λL,whereλL is wavelength of the lowest operating frequency.The antenna can operate within the frequency range from 1.63 GHz to over 8 GHz.For the AVA with parasitic patch and uniform corrugation,the overall size of antenna is 50×86 mm2 or 0.24λL×0.41λL.It can operate within the frequency range from 1.4 GHz to over 8 GHz.The maximum gain for AVA with non-uniform corrugation and AVA with parasitic patch and uniform corrugation are 9.03 and 11.31 dBi,respectively.The corrugation profile and parasitic patch of the proposed antenna are optimized to achieve the desired properties for breast cancer detection.In addition,the proposed AVAs are measured with breast phantom to detect cancerous cell inside the breast and the performance in detecting cancerous cell are discussed.The measured result can confirm that the proposed AVAs can detect unwanted cell inside the breast while maintaining the compact size,simple structure and low complexity in design.
文摘The great Lisbon earthquake Nov.1,1755 devastated the city and Portuguese coastlines down to Morocco.Many details of the event are typical signs of chaotic terrane caused by an antipodal impact.A faint but fresh-looking antipodal impact structure centered at 35°39′S,168°26′E is found in the Tasman Sea,or about 405 km WSW(West-Southwest)of Cape Reinga,North Island,NZ(North Island).By conventional geological methods,the epicenter has been inferred to be on the bottom of the Atlantic Ocean,in an area known as the Horseshoe Plain WSW of Cape St.Vincent,Portugal,at a distance of about 200 km from the cape,a round figure estimate.The impact antipode at 35°39′N,11°34′W also is located in the Horseshoe Plain at 277 km WSW of Cape St.Vincent,the implied antipodal impact quake epicenter.
文摘本文研究了 W 波段对脊鳍线过渡的波导—微带转换技术,对余弦平方渐变和 Spline 曲线渐变两种形式的对脊鳍线过渡进行了分析和仿真,并设计制作了 Spline 曲线形式的波导-对脊鳍线-微带转换,结构为背靠背。在整个 W 波段,单个过渡结构插入损耗小于1.3dB,回波损耗小于-13dB,在（90～99）GHz 内,单个过渡结构插入损耗小于1.0dB,回波损耗小于-20dB,实现了很好的宽带过渡性能。
