List-Post: [email protected] Date: 17-Feb-98 01:18:19 MsgID: OUTBOX MgTo: "TDonnelly" >INTERNET:[email protected] Subj: Re: Antenna Correlation
I too have noted the necessity to elevate a dipole at low frequencies in order to calibrate a site in vertical polarization. I understand, however, that the European practice is to set the dipole for 70 MHz instead of extending elements out to the 30 (to 70) MHz position, thus allowing full range of vertical elevation. This seems realistic, as otherwise one could only claim to achieve accurate readings at low frequencies, when vertically polarized, for elevations equivalent to what was used with a dipole. That would not only restrict the elevation angle to unrealistic levels, but would (IMO)produce overly optimistic results and leave one open to regulatory evaluation problems. Cortland ====================== Original Message Follows ==================== >> Date: 20-Jan-98 08:03:16 MsgID: 1057-30971 ToID: 72146,373 From: "TDonnelly" >INTERNET:[email protected] Subj: Antenna Correlation Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 2 ------ OzWin: Content #1, Text ------ Sender: [email protected] Received: from ruebert.ieee.org (ruebert.ieee.org [199.172.136.3]) by arl-img-4.compuserve.com (8.8.6/8.8.6/2.10) with ESMTP id LAA28317; Tue, 20 Jan 1998 11:03:34 -0500 (EST) Received: (from daemon@localhost) by ruebert.ieee.org (8.8.8/8.8.8) id KAA16677 for emc-pstc-list; Tue, 20 Jan 1998 10:55:08 -0500 (EST) From: "TDonnelly" <[email protected]> Message-ID: <[email protected]> Original-From: "TDonnelly" <[email protected]> To: "PSTC" <[email protected]> Subject: Antenna Correlation List-Post: [email protected] Date: Tue, 20 Jan 1998 10:59:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0076_01BD2592.7D859000" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.2106.4 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 Sender: [email protected] Precedence: bulk Reply-To: "TDonnelly" <[email protected]> X-Resent-To: Multiple Recipients <[email protected]> X-Listname: emc-pstc X-Info: Help requests to [email protected] X-Info: [Un]Subscribe requests to [email protected] X-Moderator-Address: [email protected] ------ OzWin: Content #2, Text ------ MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=----=_NextPart_000_0076_01BD2592.7D859000 This is a multi-part message in MIME format. ------=_NextPart_000_0076_01BD2592.7D859000 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable In ANSI C63.4 the required antenna is a half wave tuned dipole. There is an allowance that lets a broadband antenna be used provided the results can be correlated to the half wave tuned dipole. When performing radiated emissions testing to CFR 47, Part 15, using ANSI C63.4 the requirement is to height scan the receiving antenna from 1 to 4 meters. My question concerns the instance where vertical measurements are made at the lower frequencies (below 80 MHz). If the received antenna is height scanned from 1 to 4 meters at these lower frequencies the measured levels will not correlate to a half wave tuned dipole as the worst case vertical levels are typically found at lower antenna heights. It has been my experience that the height scan of the broadband antenna must be limited to the range that the half wave tuned dipole can be scanned over to demonstrate correlation. I would like to have some discussion on this issue to get a feel for how this is being addressed by others. Tom Donnelly EMC Engineer Lucent Technologies [email protected]
