Ken, Good point and well noted. I appologise if I muddied the waters. I probably should have kept my mouth (keyboard?) shut because most of my background is FCC/EU emissions and antenna design/modeling. I didn't take well enough into account the specific MIL standard you quoted and your well stated directivity issue. With respect, Brent DeWitt
From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Thursday, October 28, 2004 9:31 PM To: bdew...@ix.netcom.com; Gary McInturff; emc-p...@ieee.org Subject: Re: Vertical monopole with counterpoise radiation pattern One minor caveat to Mr. DeWitt. I was careful to talk about directivity and not gain. Gain implies power flowing into the antenna on a transmission line and power flowing out as a traveling wave. The ratio of power flowing out to in is the antenna efficiency, and that multiplied by the directivity is the gain. As I noted, the type of rod antenna used in MIL-STD-285 is electrically short, presents a very high impedance to the power source and hence does not radiate power, just electric field lines. From: "Brent DeWitt" <bdew...@ix.netcom.com> Reply-To: <bdew...@ix.netcom.com> List-Post: emc-pstc@listserv.ieee.org Date: Thu, 28 Oct 2004 20:16:51 -0700 To: "Gary McInturff" <gmcintu...@spraycool.com>, <emc-p...@ieee.org> Subject: RE: Vertical monopole with counterpoise radiation pattern Gary, The vertical monopole over counterpoise (or image plane) has the same radiation pattern as a vertical dipole in free space. If I remember correctly, it has 2.15 dB gain over isotropic at the maximum. Brent DeWitt From: owner-emc-p...@listserv.ieee.org mailto:owner-emc-p...@listserv.ieee.org]On Behalf Of Gary McInturff Sent: Thursday, October 28, 2004 4:19 PM To: emc-p...@ieee.org Subject: Vertical monopole with counterpoise radiation pattern Folks, I'm guessing that for a given dimension above the ground plane the above antenna radiates isotrophically, correct. (No - I'm not much of an antenna guy). Just trying to figure out a little about the shielding integrity test for e-fields in Mil-std- 285. Thanks Gary ---------------------------------------------------------------- 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 emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Scott Douglas emcp...@ptcnh.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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 emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Scott Douglas emcp...@ptcnh.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc