A 30 MHz tuned dipole calibrated at 3 meters is very much an antenna, and very much in the near field, even if it meets the lambda/2 pi separation criteria. I don't think most people would consider it a near field probe.
I would think that a dipole-like antenna with a broad main lobe would either be calibrated employing a height search above a ground plane, or the ground would be made anechoic. > From: Wan Juang Foo <[email protected]> > Reply-To: Wan Juang Foo <[email protected]> > Date: Wed, 21 Apr 2004 16:32:00 +0800 > To: <[email protected]>, <[email protected]> > Subject: Re: Measurement distance and antenna factor > > > > > > > > Hi, > Whatever the measurement distance, 3 m or 10 m each will have a different > set of antenna factors (mostly less than 0.5 dB difference) for any given > antenna. > Ken Javor <[email protected]> wrote on 21/04/2004 03:52 PM >> If the antenna factor is measured in the far field, whether that be >> either 3 or 10 meters, then it will not change if you measure it at >> a larger distance. But if the antenna factor is measured in the > > Agreed only if the antenna is calibrated in free space condition. I > presume free space is x>>lambda/2pi > >> near field, whether at 3 or 10 meters, then it will change at any >> other separation. > > A near field 'antenna' in the very near field is nothing but a E or H field > 'probe'. > > AFAIK, Antenna Factors for any antenna calibrated in the 'far-field' are > also know to be slightly dependant the height of (the 'measurement > antenna') used during the calibration (above the ground plane). > > Off the cuff, I can recall that there was a paper on this some years ago. > > Can anyone recall the title and details? > > Tim Foo > > > ------------------------------------------- > 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
