{"title":"Poynting's theorem, reactive energy, and radiated power","authors":"D. M. Grimes, C. Grimes","doi":"10.1109/ISEMC.1994.385637","DOIUrl":"https://doi.org/10.1109/ISEMC.1994.385637","url":null,"abstract":"An important parameter of any antenna is the ratio of standing reactive energy stored about it to the radiated power; by definition, quality factor Q is /spl omega/ times that ratio. Extensive experience and electromagnetic theory arguments based upon Q seem to agree that an efficient antenna must be about a half wavelength long in at least one dimension. But is this a general property of radiation fields, or is it due to an inadequate understanding on our part? Can the size limitations be mitigated or even bypassed? The authors re-examine the fundamentals of radiating fields and conclude that there is a significant special case that has not been adequately examined previously. They examine it and conclude that errors of omission are made in previous analyses of compound antennas and significant improvements to the operation of small antennas may be possible. They start with reactive power in radiation fields, and from it solve for the reactive energy. That energy, in turn, is used to solve for radiation Q. With simple, small spherical antennas of radius \"a\" supporting either TE or TM fields the reactive power is an orthogonal function of the fields and the accepted restrictions on small ka=2/spl pi/a/spl lambda/ values hold: the gain is about 1.8 dB, Q varies as (1/ka)/sup 3/, bandwidth as (ka)/sup 3/, and the antenna input impedance as (ka)/sup /spl plusmn/3//. Compound antennas with equal magnitude and properly phased TE+TM modes may be formed from combined linear and loop antennas. A conceptual embodiment is described, for which the reactive power is a non-orthogonal function of the fields and small (ka) restrictions are eased.<<ETX>>","PeriodicalId":154914,"journal":{"name":"Proceedings of IEEE Symposium on Electromagnetic Compatibility","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132251413","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}
{"title":"Deficiency of anechoic/semi-anechoic chambers","authors":"Y. Huang, David Edwards","doi":"10.1109/ISEMC.1994.385666","DOIUrl":"https://doi.org/10.1109/ISEMC.1994.385666","url":null,"abstract":"There is a perceived problem with the anechoic chamber facility, i.e., significant deviations from the \"standard\" open site attenuation performance have been observed at the lower end of the frequency range. The possible mechanisms leading to the observed behaviour are described and the analysis presented confirms the expected performance of such a chamber. The modelling approach, using both free-space electromagnetic radiation theory and a new representation of Dyadic Green's function for screened chamber, is straightforward and computationally efficient. The results indicate that a typical 10-m chamber facility will not perform satisfactory between about 10 MHz and 60 MHz, the exact frequencies being dependant on lining material performance. Based on this analysis, some general remedies are suggested.<<ETX>>","PeriodicalId":154914,"journal":{"name":"Proceedings of IEEE Symposium on Electromagnetic Compatibility","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126673846","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}
{"title":"Simulation of interference between Earth stations and Earth-orbiting satellites","authors":"D. F. Bishop","doi":"10.1109/ISEMC.1994.385630","DOIUrl":"https://doi.org/10.1109/ISEMC.1994.385630","url":null,"abstract":"It is often desirable to determine the potential for radio frequency interference between Earth stations and orbiting spacecraft. This information can be used to select frequencies for radio systems to avoid interference or it can be used to determine if coordination between radio systems is necessary. A model is developed that will determine the statistics of interference between Earth stations and elliptical orbiting spacecraft. The model uses orbital dynamics, detailed antenna patterns, and spectral characteristics to obtain accurate levels of interference at the victim receiver. The model is programmed into a computer simulation to obtain long term statistics of interference. Two specific examples are shown to demonstrate the model. The first example is a simulation of interference from a fixed-satellite Earth station to an orbiting scatterometer receiver. The second example is a simulation of interference from Earth exploration-satellites to a deep space Earth station.<<ETX>>","PeriodicalId":154914,"journal":{"name":"Proceedings of IEEE Symposium on Electromagnetic Compatibility","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125925484","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}
{"title":"Emission from unshielded copper wire caused by very high-speed digital data transmission","authors":"M. Hoque","doi":"10.1109/ISEMC.1994.385671","DOIUrl":"https://doi.org/10.1109/ISEMC.1994.385671","url":null,"abstract":"A computerized electromagnetic emission model has been developed to predict near-field radiation from unshielded copper wire that is used for asynchronous digital subscriber line (ADSL) transmission. The flat parallel wire is modeled as a combination of a large number of tiny dipole antennas. The twisted wire is modeled with bifilar helixes. Simulation results are presented for a drop wire configuration at customer premises and a single-section configuration in central offices (COs). Results are compared with FCC-recommended emission criteria.<<ETX>>","PeriodicalId":154914,"journal":{"name":"Proceedings of IEEE Symposium on Electromagnetic Compatibility","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124497205","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}