lambda/2 pi is only for a tuned dipole-like antenna. 2D^2/lambda is the proper expression for a high gain aperture antenna, which is definitely what the original post was about.
> From: "Derek Walton" <[email protected]> > Organization: L F Research > Reply-To: "Derek Walton" <[email protected]> > Date: Thu, 29 Apr 2004 10:40:15 -0500 > To: [email protected] > Cc: [email protected], [email protected] > Subject: RE: Near field/far field calculation > > > Classically I've used Lambda over two Pi. > > But I guess it's worth considdering that there is near field, transition > region, and far field..... > > Thoughts? > > [email protected] wrote on 4/29/2004, 9:08 AM: > >> >> What should our definition of near/far field be? My somewhat arbitrary >> definition for this case is where the fall-off in the E-field deviates >> by 1 dB from 20LOG(D/d). A better definition might be some deviation in >> the 377 ratio of E-to-H. I think I can mimic a dish by properly phasing >> many dipoles in NEC. Any comments on whether this is a valid method to >> determine the near/far field? >> >> Dave Cuthbert >> Micron Technology >> >> -----Original Message----- >> From: Wan Juang Foo [mailto:[email protected]] >> Sent: Thursday, April 29, 2004 12:31 AM >> To: drcuthbert; [email protected] >> Subject: RE: Near field/far field calculation >> >> >> >> >> >> >> >> Dave and all, >> That is a wire antenna. The far field is based on a different criteria. >> >> :-) >> >> Tim Foo >> >> [email protected] wrote on 27/04/2004 11:44 PM >>> I ran a NEC simulation to make some sense of this. >>> This is too big of a reflector for NEC to handle >>> so I made a large rhombic. The rhombic is 1 >>> meter by 1/2 meter. The receive antenna is a dipole. >>> I moved the dipole in from 80 meters 1/2 distance steps. <snip> >> >> >> >> >> ------------------------------------------- >> This message is from the IEEE EMC Society Product Safety >> Technical Committee emc-pstc discussion list. >> >> Visit our web site at: http://www.ieee-pses.org/ >> >> To cancel your subscription, send mail to: >> [email protected] >> with the single line: >> unsubscribe emc-pstc >> >> For help, send mail to the list administrators: >> Ron Pickard: [email protected] >> Dave Heald: [email protected] >> >> For policy questions, send mail to: >> Richard Nute: [email protected] >> Jim Bacher: [email protected] >> >> All emc-pstc postings are archived and searchable on the web at: >> http://www.ieeecommunities.org/emc-pstc >> > > -- > Derek N. Walton > L F Research > Poplar Grove, IL 61065, USA > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ieee-pses.org/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [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 EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
