Return-Path: X-Spam-DCC: paranoid 1102; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_30_40,HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t7FIJqTp015675 for ; Sat, 15 Aug 2015 20:19:52 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZQg1Q-0006cL-0Q for rs_out_1@blacksheep.org; Sat, 15 Aug 2015 19:17:36 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZQg1P-0006cC-MM for rsgb_lf_group@blacksheep.org; Sat, 15 Aug 2015 19:17:35 +0100 Received: from mail-wi0-f177.google.com ([209.85.212.177]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.86) (envelope-from ) id 1ZQg0J-0007kI-SW for rsgb_lf_group@blacksheep.org; Sat, 15 Aug 2015 19:17:34 +0100 Received: by wicja10 with SMTP id ja10so47671135wic.1 for ; Sat, 15 Aug 2015 11:16:12 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=vRkzFaTsVC2Q69AeEP+t0A1pp+WpLlykRTmFtqUUkjg=; b=ELPsXorxu7B2q/Qxylf++vXqcQ9zFP+l7MdOdS1JxS5eX7IF9+RhNs6xu80ZyooQnp ZH7v29hB5H9E4hqV6rqff7TD67tzt+2Jhk2mrPtQMjVTV7KzjPwEbWd7rEPIqD6UEdK4 XzCarGm+i1OXoEuQbk7lEzYBpwrT04HMPHQDSeAtsVszyShr4TcYl6bT8Odxt2SIdFUz 6GwUtiDYJbnzWmLpA4q+NwTERG2caXUHLKe7cPZuodloHDSSKUApEkXrzVDLQtab4s2p +9f5eNMkprx+AhcZnbzKqAXPsLT7kLDMSnUp4z6VY0clgVq5AyCTn5bToU0IQuy6DQ7f 6uhg== MIME-Version: 1.0 X-Received: by 10.194.119.161 with SMTP id kv1mr11612578wjb.157.1439662572007; Sat, 15 Aug 2015 11:16:12 -0700 (PDT) Received: by 10.28.98.6 with HTTP; Sat, 15 Aug 2015 11:16:11 -0700 (PDT) In-Reply-To: <99F1F2B22A504C2E817619D82E59C59B@Clemens0811> References: <1156BF06E81A40ED928F77349725D23D@gnat> <99F1F2B22A504C2E817619D82E59C59B@Clemens0811> Date: Sat, 15 Aug 2015 19:16:11 +0100 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Scan-Signature: 84016abdd353c82964b6d256164a353f Subject: Re: LF: Re: RE: Folded monopole - Food for thought Content-Type: multipart/alternative; boundary=089e01227ba0337c1c051d5d9095 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 3883 --089e01227ba0337c1c051d5d9095 Content-Type: text/plain; charset=UTF-8 Yes, but we're nearly always talking small antennas here, where Rrad is more like a few milli-ohms and the overall extra loss resistance totally dominates Andy On 15 August 2015 at 18:28, Clemens Paul wrote: > Hi Andy, > > >6dB more, not 3dB > >Height squared > > I believe it's neither 3dB nor 6dB increase for ERP. > What is squared by doubling the effective height is is Rrad. > The increase in ERP is by far not so high and depends much on Rloss > (ground and matching). > Example: > Rrad = 50 Ohm; Rloss = 50 Ohm => efficiency = 0.5 > Quadruple Rrad to 200 Ohm then efficiency = 0.8 => 2dB more. > Other Rloss values give completeley different numbers for efficiency. > > 73 > Clemens > DL4RAJ > > > >-----Original Message----- > >From: owner-rsgb_lf_group@blacksheep.org > >[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Andy Talbot > >Sent: Friday, August 14, 2015 10:38 PM > >To: rsgb_lf_group@blacksheep.org > >Subject: Re: LF: Re: RE: Folded monopole - Food for thought > > > >6dB more, not 3dB > >Height squared > > > >'jnt > > > > > >On 14 August 2015 at 22:31, Alan Melia > > wrote: > > > > > > The problem with a monopole at LF is that the effective > >height is only half (approx) the physical height. For an > >inverted L where the top length is at least twice the height, > >the effective height is close to the physical height .....so > >3dB more ERP. It may not matter so much on 160m (I used a > >16foot centre loaded "tank-whip" at one time :-)) ) but where > > > > > > > --089e01227ba0337c1c051d5d9095 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Yes, but we're nearly always talking small antennas he= re, =C2=A0where Rrad is more like a few milli-ohms and the overall extra lo= ss =C2=A0resistance totally dominates

Andy

On 15 Augu= st 2015 at 18:28, Clemens Paul <cpaul@gmx.net> wrote:
Hi Andy,

>6dB more, not 3dB
>Height squared

I believe it's neither 3dB nor 6dB increase for ERP.
What is squared by doubling the effective height is is Rrad.
The increase in ERP is by far not so high and depends much on Rloss (ground= and matching).
Example:
Rrad =3D 50 Ohm; Rloss =3D 50 Ohm =3D> efficiency =3D 0.5
Quadruple Rrad to 200 Ohm then efficiency =3D 0.8 =3D> 2dB more.
Other Rloss values give completeley different numbers for efficiency.

73
Clemens
DL4RAJ


>-----Original Message-----
>From: owner-rsgb_= lf_group@blacksheep.org
>[mailto:owner-rsg= b_lf_group@blacksheep.org] On Behalf Of Andy Talbot
>Sent: Friday, August 14, 2015 10:38 PM
>To: rsgb_lf_group@black= sheep.org
>Subject: Re: LF: Re: RE: Folded monopole - Food for thought
>
>6dB more, not 3dB
>Height squared
>
>'jnt
>
>
>On 14 August 2015 at 22:31, Alan Melia
><alan.melia@btinternet.= com> wrote:
>
>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0The problem with a monopole at LF is that th= e effective
>height is only half (approx) the physical height. For an
>inverted L where the top length is at least twice the height,
>the effective height is close to the physical height .....so
>3dB more ERP. It may not matter so much on 160m (I used a
>16foot centre loaded "tank-whip" at one time :-))=C2=A0 )=C2= =A0 but where
>
>



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