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(VPS 130911-0, 11/09/2013), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.2 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi this is interesting reading, but beware of applyiing it directly to amateur LF!. BC antennas are usually monoples and the ground requirement for those is somewhat different to an amateur antenna where height is often limited and "T" or inverted "L" antennas are used. Always size your ground extent by measuring the system, so that you know when to stop wasting copper and effort! Radials are only really effective if they are at least 1/8th wavelength....that requires a lot of real estate at LF. Also BC engineers can often choose their site, amateurs rarely can. [...] Content analysis details: (0.2 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.82.99.230 listed in list.dnswl.org] 0.2 STOX_REPLY_TYPE STOX_REPLY_TYPE 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 086f3faad0220c9ae57a7913e711a86d Subject: LF: Re: Broadcast Ground Systems Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.6 required=5.0 tests=FORGED_MUA_OUTLOOK autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Status: O X-Status: X-Keywords: X-UID: 853 Hi this is interesting reading, but beware of applyiing it directly to amateur LF!. BC antennas are usually monoples and the ground requirement for those is somewhat different to an amateur antenna where height is often limited and "T" or inverted "L" antennas are used. Always size your ground extent by measuring the system, so that you know when to stop wasting copper and effort! Radials are only really effective if they are at least 1/8th wavelength....that requires a lot of real estate at LF. Also BC engineers can often choose their site, amateurs rarely can. Alan G3NYK ----- Original Message ----- From: "David Weinreich" To: ; <600m@yahoogroups.com> Sent: Thursday, September 12, 2013 12:34 AM Subject: LF: Broadcast Ground Systems Dear LF/MFers, I have a copy of "Radio Broadcast Ground Systems" that was prepared by Smith Electronics of Cleveland, Ohio in 1972. The report provides a digest of material from Laport's book, the Antenna Engineering Handbook and the famous article by Brown, Lewis and Epstein from the IRE Proceedings. I will gladly send it to whoever wants it and is willing to pay the postage from Cleveland, Ohio. First come first served, referenced to e-mail arrival time. Best regards, David Weinreich WA2VUJ/8