Wireless Design Toolkit

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This page contains a set of equations and free javascript converters and calculators relevant to designing wireless implimentations. All the scripts are released under the GPL. The frequencies involved are, at the moment, set for 2.44 GHz to fit in line with an 802.11b WLAN (Wireless Local Area Network). With the advent of 802.11g this will be changed to allow the frequencies to be changed.

Equations:

• Free space loss (FSL)
• Range at 2.44 GHz (GigaHertz)
• Wavelength in air
• Wavelength in coaxial cable
• Impedance of coaxial cable
• Velocity factor of coaxial cable

Calculators:

• Free space loss (FSL)
• Range at 2.44 GHz
• Effective radiated power (ERP)
• Fade margin or system operating margin

Converters:

• Convert dBm and milliWatts (mW)
• Convert diameter and circumference
• Convert inches and mm (millimetres)
• Convert miles and metres
• Convert feet and metres

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Convert inches / millimetres

1 inch = 25.4 mm

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Convert circumference / diameter

C = πD

Where:

• C is the circumference of a circle
• D is diameter of a circle
• π is the constant pi =

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Convert miles / metres

1 mile = 1609 metres

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Convert feet / metres

1 foot = 0.3048 metres

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Calculate free space loss

FSL = 36.5 + (20 log₁₀(D / 1609)) + (20 log₁₀f)

Where:

• FSL is Free Space Loss in dB
• D is distance between antennas in metres
• f is frequency of signal in Hz

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Wavelength in air

L = c(1 / f)

Where:

• L is wavelength in metres
• c is the speed of light in air 299552816 metres per second
• f is frequency of signal in Hz

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Wavelength in coaxial cable

L = vc(1 / f)

Where:

• L is wavelength in metres
• c is the speed of light in a vacuum 299792458 metres per second
• f is frequency of signal in Hz
• v is the velocity factor of the coaxial cable

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Coaxial impedance

Z_o = {138 / sq_rt (E)}log₁₀(D / d)

Where:

• Z_o is the characteristic impedance in Ohms
• E is the dialectric constant
• D is the inner diameter of the outer conductor in metres
• d is the diameter of the inner conductor in metres

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Velocity factor

v = 1 / sq_rt (E)

Where:

• v is the velocity factor of coaxial cable
• E is the dialectric constant

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Period of the wave

t = 1 / f

Where:

• L is the period of the wave in seconds
• f is frequency of signal in Hz

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Calculate potential range from maximum FSL at 2.44 Ghz

D = 10^{((FSL-104.2) / 20)}1609

Where:

• FSL is Free Space Loss in dB
• D is distance between antennae in metres
• f is frequency of signal in Hz

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Calculate effective radiated power (ERP)

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Calculate system operating margin or fade margin

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Convert milliWatts / dBm

milliWatts = 10^(dBm/10)

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Copyleft

Copyright © 2002. Author: Dave Gough).
Psand Limited, 54 Goodwin Road, Ramsgate, Kent, CT11 0JJ, United Kingdom.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

If you do wish to copy this for use you will need to ensure that you have also got wireless.js and interface.js which are in the same directory as this HTML file

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