George: The formula you have, for free space attenuation due to geometrical spreading, is NOT applicable to the MW AM broadcast band.
For quick answers, without making a life's study of propagation, go to the Reference Data for Radio Engineers or similar handbook (old ones were ITT, new ones are Sams). Lacking that, check out the FCC Rules Part 73 with regard to AM stations power and field strength http://www.fcc.gov/mb/audio/bickel/amfmrule.html. There are curves there for ground-wave propagation (similar to the ITU curves John Woodgate mentions) that may answer your questions. Regards, Jacob Z. Schanker, P.E. 65 Crandon Way Rochester, NY 14618 Tel: 585 442 3909 Fax: 585 442 2182 [email protected] From: "George Stults" <[email protected]> To: <[email protected]> Sent: Thursday, December 02, 2004 1:48 PM Subject: path attenuation in AM band Hi Folks, I have an equation for the attenuation of a radiated signal as a function of (distance, frequency, and environment.) ATTN = 37 + 20 Log (Freq) + 20 Log (Dist), Freq is in MHz, Distance in Miles, Environment is free-space/line-of-sight (N=2). My information is that this equation works well for 2.4GHz frequency range. Could anyone tell me whether this equation would still make valid predictions for attenuation in the AM band. (535 - 1650)Khz, and lower? Or could anyone suggest an equation that would predict path loss as a function of distance, frequency, and environment for lower frequencies? Thanks in advance. George Stults 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/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [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 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/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [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
