Electromagnetic wave - Revision history

TheAnarcat at 16:26, 11 October 2010

2010-10-11T16:26:03Z

← Older revision		Revision as of 09:26, 11 October 2010
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	<math>f = \frac{300Mm/s}{20m} = 150Mhz</math>		<math>f = \frac{300Mm/s}{20m} = 150Mhz</math>

	Those calculations are very useful to find the length of a good antenna, as [[antennas]] operate better when they have a size that is close to the wavelength or an integer multiple of the half-wavelength.

	=== Calculating the wavelength ===		=== Calculating the wavelength ===
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	This is in the [[70cm]] band.		This is in the [[70cm]] band.

			Those calculations are very useful to find the length of a good antenna, as [[antennas]] operate better when they have a size that is close to the wavelength or an integer multiple of the half-wavelength.

	== See also ==		== See also ==

2010-10-11T16:25:23Z

Basic trick

← Older revision		Revision as of 09:25, 11 October 2010
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	Here, '''f'''' is in Mhz and a '''Mm/s''' is a mega-meter per second.		Here, '''f'''' is in Mhz and a '''Mm/s''' is a mega-meter per second.

	== Basic ~~trick~~ ==		== Basic tricks ==

	'''Just dive 300 by the number you have to get the number you want. Don't forget to convert to megahertz first. ~~The wavelength~~ is always in meters.'''		# '''Just dive 300 by the number you have to get the number you want.'''
			# '''Don't forget to convert to megahertz first.'''
			# '''Wavelength is always in meters.'''

	== Example calculations ==		== Example calculations ==

2010-10-11T16:24:33Z

@@ Line 1: / Line 1: @@
 The image below is of a pure sine wave  <math> y = sinx </math>
@@ Line 15: / Line 13: @@
 The velocity of electromagnetic waves is close to the speed of light in the atmosphere, approximately 300 000 000 m/s.
-== Some Math==
+== Basic formulas ==
 * Velocity = Frequency x Wavelength   <math> v = f \times \lambda </math>
-* Period = 1/frequency  <math> p = \frac {1}{f} </math>
+Since velocity is the speed of light and is constant, we denote it with the letter '''c''':
 {{electronics}}
 {{propagation}}

2010-10-03T14:24:02Z

← Older revision	Revision as of 07:24, 3 October 2010
(No difference)

2010-10-03T14:08:33Z

Electromagnetic Waves moved to Electromagnetic waves: lowercase second word, more intuitive for linking and default capitalisation in mediawiki

← Older revision	Revision as of 07:08, 3 October 2010
(No difference)

2009-04-09T01:26:53Z

Some Math

← Older revision		Revision as of 18:26, 8 April 2009
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	* Period = 1/frequency <math> p = \frac {1}{f} </math>		* Period = 1/frequency <math> p = \frac {1}{f} </math>



			{{electronics}}
			{{propagation}}

2008-08-27T06:45:37Z

added some detail probably needs more

← Older revision		Revision as of 23:45, 26 August 2008
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	Related wiki pages: [[SWR]], [[Propagation]], [[Electronic Theory]], [[harmonics]]		Related wiki pages: [[SWR]], [[Propagation]], [[Electronic Theory]], [[harmonics]]

			The image below is of a pure sine wave <math> y = sinx </math>

			* The Amplitude of the wave '''a''' is the distance from the median line of the wave to either a peak or a trough.

			* The wavelength <math> \lambda </math> is the distance betwwen two corresponding point on successive waves, and is measured in metres.

	[[Image:Vk4yeh_EM_wave.jpg \|400px]]		[[Image:Vk4yeh_EM_wave.jpg \|400px]]

			* The period of a wave is the time it takes for it to pass a fixed reference point, and is measured in seconds.

			* Frequency is the number of waves that pass a fixed reference point per second, with units Hertz (Hz) where 1 Hz = 1 complete cycle per second.

			The velocity of electromagnetic waves is close to the speed of light in the atmosphere, approximately 300 000 000 m/s.

			== Some Math==

			* Velocity = Frequency x Wavelength <math> v = f \times \lambda </math>

			* Period = 1/frequency <math> p = \frac {1}{f} </math>

2008-08-26T20:36:17Z

added graph - no other info yet

New page

Related wiki pages: [[SWR]], [[Propagation]], [[Electronic Theory]], [[harmonics]]

[[Image:Vk4yeh_EM_wave.jpg |400px]]