For years I have understood that the Gain and Antenna factor are related by the following equation: AF=20 log (F[GHz])-G[isotropic]+30.3 And the E field (dBV/m) is given by E=P[dBW.ant]+G+14.77: this equation is for 1m separation. P[dBW.ant] is the power at the antenna. If 1m is actually in the far field of the antenna, then it is possible to extend this equation by adding a term of [-20log(1/D) where D is the distance in metres. There is some myth that the power at the antenna is the forward power minus the reflected power. The gain / antenna factor measurement includes the mismatch and when using the gain to calculate the field, the mismatch is therefore accommodated automatically. Regards Tim PS I have some proofs in MathCad somewhere if anyone wants to take a look. Tim
************************ Tim Haynes Electromagnetic Engineering Specialist SELEX Galileo, A Finmeccanica Company 300 Capability Green Luton LU1 3PG (Phone () +44 (0) 1582 886239 (Mob )) +44 (0) 7540629920 (Fax 7)+44 (0)1582 795863 (Email *) [email protected] www.selexgalileo.com P Please consider the environment before printing this email. There are 10 types of people in the world-those who understand binary and those who don't. J. Paxman ________________________________ From: Rodrigo Rodriguez [mailto:[email protected]] Sent: 12 May 2010 17:36 To: [email protected] Subject: [PSES] Antenna TAF calculated from AF *** WARNING *** This message has originated outside your organisation, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Hello all, I would appreciate your comments/guidance about this question. I have a calibrated biconical antenna and its calibration report includes its AF (antenna factor) and the Gain at 1 meter. I would like to get the corresponding TAF (Transmit Antenna Factor) for this antenna at 1 m, 3 m and 10 m. The question is, Is it possible calculate TAF for distances at 1 m, 3 m & 10 m using the AF at 1 m? It may be a different situation for the 1 m as I already have the AF at that distance. Do I need to get the calibrated AF for the other two distances? Thank you very much. Rodrigo Rodriguez ________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. Get busy. <http://www.windowsl ve.com/campaign/thenewbusy?tile=multiac ount&ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]> SELEX Galileo Ltd Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS14 3EL A company registered in England & Wales. Company no. 02426132 ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]>
