Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324934
Xuyang Li, K. Sam, W. Wiesbeck, T. Zwick
The radiation pattern in the far-field of on- and in-body antennas for medical application cannot be directly measured, since the used tissue mimicking liquid results in a high signal attenuation and thus, the measurement distance is strongly limited. A planar-rectangular near-field antenna measurement system is proposed in this paper. The near-field electric field is measured and the far-field pattern is processed through NF-FF Transformation. PEG-Water solution at different concentrations can be used to emulate the dielectric properties of different tissues. This allows the characterization of the antenna in tissues mimicking liquid, under more realistic wave propagation, which will be of great help to analyze the performance of these antennas. The measurement results confirm that this measurement system is feasible to measure the radiation pattern in both E- and H-plane of the antennas.
{"title":"A planar near-field measurement system of UWB antennas for medical diagnostics","authors":"Xuyang Li, K. Sam, W. Wiesbeck, T. Zwick","doi":"10.1109/APWC.2012.6324934","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324934","url":null,"abstract":"The radiation pattern in the far-field of on- and in-body antennas for medical application cannot be directly measured, since the used tissue mimicking liquid results in a high signal attenuation and thus, the measurement distance is strongly limited. A planar-rectangular near-field antenna measurement system is proposed in this paper. The near-field electric field is measured and the far-field pattern is processed through NF-FF Transformation. PEG-Water solution at different concentrations can be used to emulate the dielectric properties of different tissues. This allows the characterization of the antenna in tissues mimicking liquid, under more realistic wave propagation, which will be of great help to analyze the performance of these antennas. The measurement results confirm that this measurement system is feasible to measure the radiation pattern in both E- and H-plane of the antennas.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86144682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324907
P. Meaney, Amir H. Golnabi, M. Pallone, N. Epstein, P. Kaufman, S. Geimer, K. Paulsen
We have imaged several breast cancer patients at multiple intervals during her neoadjuvant chemotherapy to assess the capability of microwave tomography as a therapy monitoring device. For the patient discussed here, we illustrate the spectral behavior of our tomographic approach in the context of a complex imaging situation with a large scattering tumor along with less frequently encountered structures such as thickened skin in the tumor vicinity. These results demonstrate that the microwave technology is sensitive to dielectric property perturbations associated with treatment-induced physiological changes. In addition, it also confirms previously hypothesized notions that the lower frequency images provide lower resolution but useful counterparts to the enhanced resolution, higher frequency images. This spectral data can be instructive for both UWB radar approaches and multi-frequency or time-domain tomographic approaches. The chemotherapy patients are unique with respect to breast cancer imaging cases in that they usually involve electrically large tumors along with other non-standard features such as extra-thick skin (easily as thick as 1 cm). These large, high contrast features are quite challenging for all types of microwave imaging (radar and tomography-based) and form an important benchmark for testing imaging techniques. For our efforts, we have developed a log transformation as part of the image reconstruction process which we have shown to have superior convergence behavior (i.e. no local minima) while retaining phase wrapping information that is generally lost when only considering more classical minimization criteria. As we will show, this technique requires broadband scattering data which we provide from measurements using our ultrawideband monopole antennas.
{"title":"Spectral imaging for complex clinical breast structures","authors":"P. Meaney, Amir H. Golnabi, M. Pallone, N. Epstein, P. Kaufman, S. Geimer, K. Paulsen","doi":"10.1109/APWC.2012.6324907","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324907","url":null,"abstract":"We have imaged several breast cancer patients at multiple intervals during her neoadjuvant chemotherapy to assess the capability of microwave tomography as a therapy monitoring device. For the patient discussed here, we illustrate the spectral behavior of our tomographic approach in the context of a complex imaging situation with a large scattering tumor along with less frequently encountered structures such as thickened skin in the tumor vicinity. These results demonstrate that the microwave technology is sensitive to dielectric property perturbations associated with treatment-induced physiological changes. In addition, it also confirms previously hypothesized notions that the lower frequency images provide lower resolution but useful counterparts to the enhanced resolution, higher frequency images. This spectral data can be instructive for both UWB radar approaches and multi-frequency or time-domain tomographic approaches. The chemotherapy patients are unique with respect to breast cancer imaging cases in that they usually involve electrically large tumors along with other non-standard features such as extra-thick skin (easily as thick as 1 cm). These large, high contrast features are quite challenging for all types of microwave imaging (radar and tomography-based) and form an important benchmark for testing imaging techniques. For our efforts, we have developed a log transformation as part of the image reconstruction process which we have shown to have superior convergence behavior (i.e. no local minima) while retaining phase wrapping information that is generally lost when only considering more classical minimization criteria. As we will show, this technique requires broadband scattering data which we provide from measurements using our ultrawideband monopole antennas.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77942129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324977
J. C. Smit, J. Cilliers
Recently, a set of high resolution radar measurements were undertaken in South Africa to gain insight into factors influencing the detectability of submarine masts deployed under realistic operational conditions. The measurements, processing results and some insights gained are described in [1]. The current paper presents the results of a subsequent computational electromagnetic (CEM) simulation investigation of a simplified mast model in a realistic sea surface environment. The results illustrate some of the effects of the sea surface reflection interaction on the observed RCS of a submarine mast.
{"title":"Insights into factors contributing to the observability of a submarine at periscope depth by modern radar: Part 2 - EM simulation of mast RCS in a realistic sea surface environment","authors":"J. C. Smit, J. Cilliers","doi":"10.1109/APWC.2012.6324977","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324977","url":null,"abstract":"Recently, a set of high resolution radar measurements were undertaken in South Africa to gain insight into factors influencing the detectability of submarine masts deployed under realistic operational conditions. The measurements, processing results and some insights gained are described in [1]. The current paper presents the results of a subsequent computational electromagnetic (CEM) simulation investigation of a simplified mast model in a realistic sea surface environment. The results illustrate some of the effects of the sea surface reflection interaction on the observed RCS of a submarine mast.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87990364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324976
F. Anderson, K. Naicker, J. Mocke
A set of high range and Doppler resolution radar measurements were performed to gain insights into factors influencing the detectability of submarine masts deployed at periscope depth under realistic operational conditions. This paper describes the measurements, processing results and some insights gained. It is followed by a companion paper [2] describing a subsequent computational electromagnetic (CEM) simulation investigation of a simple mast model in a realistic sea surface environment. It was performed to gain insights into the physics leading to some of the unexpected observed effects reported in this paper.
{"title":"Insights into factors contributing to the observability of a submarine at periscope depth by modern radar. part 1 - high resolution measurements","authors":"F. Anderson, K. Naicker, J. Mocke","doi":"10.1109/APWC.2012.6324976","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324976","url":null,"abstract":"A set of high range and Doppler resolution radar measurements were performed to gain insights into factors influencing the detectability of submarine masts deployed at periscope depth under realistic operational conditions. This paper describes the measurements, processing results and some insights gained. It is followed by a companion paper [2] describing a subsequent computational electromagnetic (CEM) simulation investigation of a simple mast model in a realistic sea surface environment. It was performed to gain insights into the physics leading to some of the unexpected observed effects reported in this paper.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87355598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324903
M. Takikawa, Y. Inasawa, Y. Konishi
We propose a new compact center-fed reflector antenna with one-dimensional beam scanning function for small satellite application. The proposed antenna has different curves in orthogonal two cross sections. The beam scanning cross section is an imaging reflector form. The non-beam scanning cross section is an axial symmetry Cassegrain form. In this paper, we describe the design method of the proposed antenna based on a doubly curved reflector. The measurement of a prototype antenna demonstrates the validity of the proposed antenna.
{"title":"One-dimensional beam scanning reflector antenna for small satellite applications","authors":"M. Takikawa, Y. Inasawa, Y. Konishi","doi":"10.1109/APWC.2012.6324903","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324903","url":null,"abstract":"We propose a new compact center-fed reflector antenna with one-dimensional beam scanning function for small satellite application. The proposed antenna has different curves in orthogonal two cross sections. The beam scanning cross section is an imaging reflector form. The non-beam scanning cross section is an axial symmetry Cassegrain form. In this paper, we describe the design method of the proposed antenna based on a doubly curved reflector. The measurement of a prototype antenna demonstrates the validity of the proposed antenna.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76034728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324982
J. Malherbe
The performance of a TEM horn with hybrid elliptic functions describing the plate width an plate separation is enhanced by the inclusion of a pair of internal fins. The inclusion of the fins provides further control over the H-plane radiation pattern, enabling the horn to perform beyond 42 GHz.
{"title":"Hybrid elliptic TEM horn with internal fins","authors":"J. Malherbe","doi":"10.1109/APWC.2012.6324982","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324982","url":null,"abstract":"The performance of a TEM horn with hybrid elliptic functions describing the plate width an plate separation is enhanced by the inclusion of a pair of internal fins. The inclusion of the fins provides further control over the H-plane radiation pattern, enabling the horn to perform beyond 42 GHz.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77906510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324988
O. Breinbjerg
This paper reviews research in the Geometrical Theory of Diffraction (GTD) and the Physical Theory of Diffraction (PTD) at the Technical University of Denmark (DTU). The year 2012 celebrates the 50th anniversary of the seminal works of J.B. Keller on GTD and P. Ya Ufimtsev on PTD - two closely connected theories for high-frequency diffraction of electromagnetic waves.
本文综述了丹麦技术大学(DTU)在几何衍射理论(GTD)和物理衍射理论(PTD)方面的研究。2012年是J.B. Keller关于GTD和P. Ya Ufimtsev关于PTD的开创性作品50周年，这两个密切相关的电磁波高频衍射理论。
{"title":"GTD and PTD at DTU","authors":"O. Breinbjerg","doi":"10.1109/APWC.2012.6324988","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324988","url":null,"abstract":"This paper reviews research in the Geometrical Theory of Diffraction (GTD) and the Physical Theory of Diffraction (PTD) at the Technical University of Denmark (DTU). The year 2012 celebrates the 50th anniversary of the seminal works of J.B. Keller on GTD and P. Ya Ufimtsev on PTD - two closely connected theories for high-frequency diffraction of electromagnetic waves.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76372925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324924
Yifei Shi, A. Amert, K. Whites
A novel approach for miniaturization of disc monopole antennas is presented. The physical size of the antenna has been miniaturized by loading a dielectric material of high dielectric constant around the antenna in an intelligent manner. In order to maintain the impedance bandwidth characteristics, a spatial quarter wave transformer was applied. Simulations of the structure showed that the impedance bandwidth was conserved while the physical size of the structure was reduced by 58.4%.
{"title":"Can ultrawideband antennas be miniaturized effectively by dielectric loading?","authors":"Yifei Shi, A. Amert, K. Whites","doi":"10.1109/APWC.2012.6324924","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324924","url":null,"abstract":"A novel approach for miniaturization of disc monopole antennas is presented. The physical size of the antenna has been miniaturized by loading a dielectric material of high dielectric constant around the antenna in an intelligent manner. In order to maintain the impedance bandwidth characteristics, a spatial quarter wave transformer was applied. Simulations of the structure showed that the impedance bandwidth was conserved while the physical size of the structure was reduced by 58.4%.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74705693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324979
C. Vale
We present what we believe to be two novel and related antenna topologies that find application in radio direction finding (DF). A topology for a stabilised anti-phase dual-fed loop antenna is presented that reduces sensitivity to cross-polarised wave incidence, increases loop gain at higher frequencies and provides improved pattern stability when compared to traditional loop antenna designs. Additionally, we present a hybrid Adcock/loop topology that provides the desirable qualities of Adcock arrays at high frequencies whilst substantially improving the low frequency sensitivity of electrically small Adcock arrays. Design and measurements are presented for both variations.
{"title":"Variations on loop and Adcock array topologies for improved radio direction finding performance","authors":"C. Vale","doi":"10.1109/APWC.2012.6324979","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324979","url":null,"abstract":"We present what we believe to be two novel and related antenna topologies that find application in radio direction finding (DF). A topology for a stabilised anti-phase dual-fed loop antenna is presented that reduces sensitivity to cross-polarised wave incidence, increases loop gain at higher frequencies and provides improved pattern stability when compared to traditional loop antenna designs. Additionally, we present a hybrid Adcock/loop topology that provides the desirable qualities of Adcock arrays at high frequencies whilst substantially improving the low frequency sensitivity of electrically small Adcock arrays. Design and measurements are presented for both variations.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91039882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-08DOI: 10.1109/APWC.2012.6324957
Y. Rahmat-Samii
In his landmark paper dated February 1962, Prof. Keller introduced the notion of Keller's cone and stated, “Geometrical optics, the oldest and most widely used theory of light propagation, fails to account for certain optical phenomena called diffraction...”. I had a personal encounter with Keller's cone at a hotel in Florida! In an early morning on October 14, 2007, I witnessed Keller's cone on the door of my hotel room resulting from edge diffraction from a TV stand due to the sun rays coming through an opening of a window curtain. By now we know how to construct the local plane wave behavior of the diffracted field along the diffracted rays by invoking the fact that an edge forms one of the caustics of the diffracted wave front. We also know that the diffracted field is of the order of k-1/2 in comparison to the geometrical optics field which is of the order of k0. In many antenna and scattering problems this added diffracted term enhances the accuracy of the total field immensely. Due to the boundary layer properties of the diffracted ray field, along the incident and shadow boundaries and also caustics the original form of Keller's construction fails. This shortcoming has been overcome through construction of the Uniform Theory of Diffraction (UTD by Kouyoujian and Pathak), Uniform Asymptotic Theory (UAT by Ahluwalia, Beorsma, Lewis, Lee and Deschamps) and the Spectral Theory of Diffraction (STD by Rahmat-Samii and Mittra). An overview and salient features of these theories are revisited in a novel and unified manner.
{"title":"GTD, UTD, UAT and STD: A Historical Revisit","authors":"Y. Rahmat-Samii","doi":"10.1109/APWC.2012.6324957","DOIUrl":"https://doi.org/10.1109/APWC.2012.6324957","url":null,"abstract":"In his landmark paper dated February 1962, Prof. Keller introduced the notion of Keller's cone and stated, “Geometrical optics, the oldest and most widely used theory of light propagation, fails to account for certain optical phenomena called diffraction...”. I had a personal encounter with Keller's cone at a hotel in Florida! In an early morning on October 14, 2007, I witnessed Keller's cone on the door of my hotel room resulting from edge diffraction from a TV stand due to the sun rays coming through an opening of a window curtain. By now we know how to construct the local plane wave behavior of the diffracted field along the diffracted rays by invoking the fact that an edge forms one of the caustics of the diffracted wave front. We also know that the diffracted field is of the order of k-1/2 in comparison to the geometrical optics field which is of the order of k0. In many antenna and scattering problems this added diffracted term enhances the accuracy of the total field immensely. Due to the boundary layer properties of the diffracted ray field, along the incident and shadow boundaries and also caustics the original form of Keller's construction fails. This shortcoming has been overcome through construction of the Uniform Theory of Diffraction (UTD by Kouyoujian and Pathak), Uniform Asymptotic Theory (UAT by Ahluwalia, Beorsma, Lewis, Lee and Deschamps) and the Spectral Theory of Diffraction (STD by Rahmat-Samii and Mittra). An overview and salient features of these theories are revisited in a novel and unified manner.","PeriodicalId":6393,"journal":{"name":"2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86719897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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