I don't know what the originating post was, I came into it when the question was about how to define/determine the far field of an antenna.
Relative to the larger question, about how to control BPL leakage so as not interfere with licensed users of the HF/shortwave band, I offer the following which is nothing more than a summary of several of my recent posts. My opinion only: It is a colossal waste of time to develop intricate models of various radiating geometries and calculate their radiating patterns. Every single home and situation will be different. The following approach is, again in my opinion, the only practical one. Determine the minimum separation distance between culprit BPL source and victim user. It would be impractical to control BPL leakage such that a short-wave antenna could be within one meter of the power line and not suffer degradation. At three meters separation between short-wave antenna and power line, that likely puts you outside the house with the BPL service. So it seems to me, from this crude generalization, that short-wave reception and BPL internet connection may not be compatible within one user's home. He/she will need to choose one or the other. As long as that choice is available and not forced by other BPL users driving noise into his/her house, that seems a reasonable solution. Following this line of reasoning, ten meters would be an appropriate distance for controlling BPL emissions. Note that this will not work for apartment/flat dwellers, and widespread BPL use may make apartment/flat dwelling incompatible with amateur short-wave reception. But whether we pick three or ten or thirty meters or any other target culprit/victim separation, once we do that we can derive a relationship between BPL rf current on an ideal transmission line and the radiated electromagnetic wave at some distance away. We model the transmission line so that we pick up the maximum lobe, and the transmission line is a realistic worst case model of reality. This can be done on the back of an envelope, and that is the level of detail in the model that is both necessary and sufficient to derive a limit for universal application. > From: "David Cuthbert" <[email protected]> > Date: Tue, 8 Aug 2006 09:26:02 -0600 > To: <[email protected]> > Subject: RE: Near field/Far field what is D. > > Correct me if I'm wrong, but the subject of the original post is the field > strength versus distance for BPL "leakage" from 1 - 30 MHz. > > I set up a simplified NEC-2 model of a house with wiring and began to > measure the field strength from 1 to 30 MHz at distances from 10 to 100 > meters. This proved to be quite a task with the sharp nulls in the pattern > at the upper end of the range. If there is any interest in these results I > can continue and then send them out. > > The BPL issue is of great interest to the amateur radio community and also > to short wave listeners. The BPL equipment does have provisions to notch out > particular bands but it has been reported that there is still objectionable > interference to licensed HF services. > > The utilitarian debate is about whether the benefits to BPL users outweigh > the losses experienced by the licensed services. > > Dave Cuthbert > > > LINEAR TECHNOLOGY CORPORATION > > Internet Email Confidentiality Footer > > This e-mail transmission, and any documents, files or previous e-mail > messages attached to it may contain confidential information that is legally > privileged. IF you are not the intended recipient, or a person responsible > for delivering it to the intended recipient, you are hereby notified that > any disclosure, copying, distribution or use of any of the information > contain in or attached to this transmission is STRICTLY PROHIBITED. If you > have received this transmission in error, please immediately notify me by > reply e-mail, or by telephone at (719)593-1579, and destroy the original > transmission and its attachments without reading or saving in any manner. > Thank You > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
