Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-df05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 3C00838000111; Sun, 13 May 2012 16:54:34 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1STfnR-0001my-7g for rs_out_1@blacksheep.org; Sun, 13 May 2012 21:53:41 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1STfnQ-0001mp-L3 for rsgb_lf_group@blacksheep.org; Sun, 13 May 2012 21:53:40 +0100 Received: from nm11-vm0.bullet.mail.ird.yahoo.com ([77.238.189.218]) by relay1.thorcom.net with smtp (Exim 4.77) (envelope-from ) id 1STfnO-0008WT-S8 for rsgb_lf_group@blacksheep.org; Sun, 13 May 2012 21:53:39 +0100 Received: from [77.238.189.53] by nm11.bullet.mail.ird.yahoo.com with NNFMP; 13 May 2012 20:53:36 -0000 Received: from [212.82.108.226] by tm6.bullet.mail.ird.yahoo.com with NNFMP; 13 May 2012 20:53:36 -0000 Received: from [127.0.0.1] by omp1003.bt.mail.ird.yahoo.com with NNFMP; 13 May 2012 20:53:36 -0000 X-DKIM-Result: Domain=btopenworld.com Result=Signature OK X-Yahoo-Newman-Id: 182685.60895.bm@omp1003.bt.mail.ird.yahoo.com Received: (qmail 67040 invoked from network); 13 May 2012 20:53:36 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=DKIM-Signature:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=Y7SN6tG4PIH1mhbLzEt0jOqN49x4BmOcmAahZcUNR96Yo8JOngZ/fdXVwprIXY7m+xi2rgBm52IfXUF9SnRD4rEfk6B6TsvZJ+WGaGBqeuWhCY2SXveoxWsDzgS10BNBKqdW3oUBF6gkrKUwrOTlbSZ/PcileoeJlb+NoNqcfw8= ; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btopenworld.com; s=s1024; t=1336942415; bh=RnT8nxDvCiuPqgqzlYSqV+aAWs7FloC0tMXtvmiFyhk=; h=X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=uBhqZ9x3xkv6WtcsvSIF9E7v55bwxUfZfjCduLeKgdJT9jPP9UuBzk/SlLkIYK3CHoVs8Ipsz27+oxnm/+LBQnNsa3wogPhiL+XFKrReDfHDFF+cp3s1r7L88DsF0p0e9K2aXAlz0xJB7wgaLyrHknSMZ9YTAmJ5KYv/hruu6A8= X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: MHEUMpUVM1mOS0wAt5SVWICbCVts4z06TUpbWCP3wtgVV5W L_CCqnu0FklDiTPX7kZd0Smbyo1DDnJ8a2Pd14XzpUqhPx5n24ONR9MfZ2oX oIAIcN3GFlpNDf75LlG0R9k6quMiiRCffWzEgQlM5f_qrHFEFHUEgIlnIADu HN_XVQxzKe5bKupDEjddk0U.8URluM_swhQ.KA3tBD4JIAGgEQk7i1cUqPtX JsH2j_8kgjmX19Yvr5TdE9JLwz0Fr0xZGe4wobR_._RAcjW4nLuJQa6wSdOT tjf5V19y1pMbZmzpeA2oaacF1kIDGeElKrld9e8USw_w73qQA1jYv_v_YwyF 59sQy7.3UN_FWQS1kGmQFvaAtU7jmpCct1yFtlIB6SGwjYWHLoZiRfmnwblR CgMR1qQNgighNYhIlAlgH1tThaH0_BYJcYw-- X-Yahoo-SMTP: Cxhli3eswBD1ozmtAojhjrja86kWx0Qm9tycD5QR1DKWrOLgjJcXkw-- Received: from JimPC (james.moritz@86.173.191.143 with login) by smtp816.mail.ukl.yahoo.com with SMTP; 13 May 2012 13:53:35 -0700 PDT Message-ID: <6BD841B4052649AAB13E29190B544C4E@JimPC> From: "James Moritz" To: References: <4FAFEA71.8030700@iup.uni-heidelberg.de> In-Reply-To: <4FAFEA71.8030700@iup.uni-heidelberg.de> Date: Sun, 13 May 2012 21:53:34 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 X-Spam-Score: 0.0 (/) 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: Dear Stefan, LF Group, I have used terminated loops of the K9AY and EWE type on LF and MF - they work well down to VLF also. They offer a simple way of obtaining a cardioid pattern; a null of 20 - 30dB can be obtained if the terminating resistor is carefully adjusted - this means it must be possible to distinguish between QRM and general band noise so that the null can be detected. The physical design is not critical - changing the shape or size of the loop does not matter much as far as directivity is concerned, although the terminating resistance will have to be adjusted for the best null, and the signal level will be greater for bigger sized loops. I found values near 200R were right in the VLF - MF range, which is a bit lower than the values given for HF use. The resistor value also seems to depend somewhat on the antenna environment. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [77.238.189.218 listed in list.dnswl.org] 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 2e2f7cbbe9f38dd7bf3fac4fc012e6fc Subject: LF: Re: Cardioid RX antenna for LF... Content-Type: text/plain; format=flowed; charset="ISO-8859-15"; reply-type=response 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=0.1 required=5.0 tests=MISSING_OUTLOOK_NAME 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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:433481568:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d310.2 ; domain : btopenworld.com DKIM : fail x-aol-sid: 3039ac1d40d94fb01f8a3329 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Dear Stefan, LF Group, I have used terminated loops of the K9AY and EWE type on LF and MF - they work well down to VLF also. They offer a simple way of obtaining a cardioid pattern; a null of 20 - 30dB can be obtained if the terminating resistor is carefully adjusted - this means it must be possible to distinguish between QRM and general band noise so that the null can be detected. The physical design is not critical - changing the shape or size of the loop does not matter much as far as directivity is concerned, although the terminating resistance will have to be adjusted for the best null, and the signal level will be greater for bigger sized loops. I found values near 200R were right in the VLF - MF range, which is a bit lower than the values given for HF use. The resistor value also seems to depend somewhat on the antenna environment. The main disadvantages are that the output signal level is quite low, so a low noise preamp will be needed with almost all receivers, and that these antennas take up quite a lot of space. If space is restricted, the same result can be achieved by combining the outputs of small loop and E-field antennas using amplitude and phase adjusting networks to achieve a cardiod pattern, but the terminated loops need less electronics, and require minimal adjustment over quite a wide bandwidth. Cheers, Jim Moritz 73 de M0BMU