Return-Path: <majordom@post.thorcom.com>
Received: (qmail 27881 invoked from network); 1 Jul 1999 00:39:10 +0100
Received: from magnet.plus.net.uk (HELO magnet.force9.net) (195.166.128.26) by guiness.force9.net with SMTP; 1 Jul 1999 00:39:10 +0100
Received: (qmail 20264 invoked from network); 30 Jun 1999 23:39:57 -0000
Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by magnet.plus.net.uk with SMTP; 30 Jun 1999 23:39:57 -0000
X-Priority: 3
Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 10yThk-0007bP-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 28 Jun 1999 06:11:40 +0100
X-MSMail-Priority: Normal
Received: from mail2.hamilton-standard.com ([153.4.57.12]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 10yThj-0007bG-00 for rsgb_lf_group@blacksheep.org; Mon, 28 Jun 1999 06:11:40 +0100
Received: from curly.hsd.utc.com by mail2.hamilton-standard.com; (8.9.1/) id BAA18282; Mon, 28 Jun 1999 01:16:52 -0400 (EDT)
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106
Received: from umrsvr.hsd.utc.com by curly.hsd.utc.com; (5.65v3.2/1.1.8.2/27Feb96-0334PM) id AA06502; Mon, 28 Jun 1999 01:10:43 -0400
Received: from nmex01nt.hsd.utc.com by umrsvr.hsd.utc.com; (5.65v3.2/1.1.8.2/27Feb96-0334PM) id AA12037; Mon, 28 Jun 1999 01:10:36 -0400
Received: by nmex01nt.hsd.utc.com with Internet Mail Service (5.5.2448.0) id <NWDGMSRP>; Mon, 28 Jun 1999 07:09:49 +0100
Message-ID: <C6ABA8DEC115D311A29D00105ABD3264031489@nmex01nt.hsd.utc.com>
From: "Soegiono, Gamal" <soegiono@nmex01nt.hsd.utc.com>
To: rsgb_lf_group@blacksheep.org
Subject: LF: radiation resistance & reactance
Date: Mon, 28 Jun 1999 07:09:49 +0100
X-Mailer: Internet Mail Service (5.5.2448.0)
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>
Content-type: text/plain; charset=windows-1252; format=flowed
MIME-Version: 1.0
Content-transfer-encoding: 8bit

Hello all,

here some equations I found in my book regarding
radiation resistance of dipoles and monopoles:



the original equation based on current profile on dipole/monopole,
all other published equations are derivates therof.

l=physical half length of dipole [m]
d=physical diameter of dipole [m]
w=wavelength in [m]
f=radian angle

k=2*PI*l/w

Rs=120 Ohms / (sin^2(k)*INTEGRAL(f=0 to
0.5*PI){[cos(k*sin(f))-cos(k)]^2/cos(f) df}

restriction: l/w =< 0.38



simple Approximation
Rs=80 Ohms * [1-1.32*(l/w)^2] * tan^2(PI*l/w)

restriction: l/w =< 0.25


more simpler Approximation
Rs=790 Ohms * (l/w)^2

restriction: l/w =< 0.14


Rs for Monopole above groundplane is half the
dipole value in each of above equation, when 
l=the physical height of the monopole in [m]




Additionally the equations to calculate the
antenna reactance:

l=physical half length of dipole [m]
d=physical diameter of dipole [m]
w=wavelength in [m]
f=radian angle

Zw=120 Ohms * [ln(4*l/d) -1]

k=2*PI*l/w

Xd=X1d-(Zw/(tan(k)))
Xm=X1m-(Zw/(tan(k)))

restriction: l/w =< 0.25

X1d=552 Ohms * (l/w)^1.85  if 0.14 <= l/w <=0.25
X1d=156 Ohms * (l/w)^1.22  if l/w < 0.14

X1m=276 Ohms * (l/w)^1.85  if 0.14 <= l/w <=0.25
X1m=78 Ohms * (l/w)^1.22  if l/w < 0.14

Best 73 

Gamal Soegiono (SWL)

50N01 / 08E27 / JO 40 fa
soegiono@nmex01nt.hsd.utc.com