I was looking around on Google for simple articles on the best way to understand radio wave lengths (vhf, uhf, etc.) and the difference between them, but I couldn't find much. Could anyone point me in the right direction on finding stuff like that?
Best way to understand Freq Wavelengths?
- Thread starter Rt169Radio
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Ubbe
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You can see radio waves as waves on the ocean. If they apperar more frequent they have a higher frequency. If they are more long stretched and far between they are less frequent and have a lower frequency. If a ship is on the ocean it will block the waves and almost nothing are left at the other side of the ship but the waves spread into that void and after a distance the waves are almost restored again.
If the waves are high they are stronger and more powerful but if the waves are low and hardly seen they will dissapear completly behind that ship.
If the waves hit a hard surface like a rock shore or a concrete pier or wave blocker they will reflect and bounce back out the reverse way to the ocean. If the waves hit a smooth sand shore they will be consumed by the sand and not bounce out again.
/Ubbe
If the waves are high they are stronger and more powerful but if the waves are low and hardly seen they will dissapear completly behind that ship.
If the waves hit a hard surface like a rock shore or a concrete pier or wave blocker they will reflect and bounce back out the reverse way to the ocean. If the waves hit a smooth sand shore they will be consumed by the sand and not bounce out again.
/Ubbe
nd5y
Member
Spectrum - The RadioReference Wiki
The higher the frequency (cycles per second) the faster the radio wave has to change direction in order to fit more cycles into that one second. They only way it can do that is to travel a shorter distance (wavelength) per cycle.
Put another way, if someone tells you to drive your car forward and backward one time (an equal distance forward and backward) at a specific speed in ten seconds, you will drive forward a certain distance, lets say 50 feet in 5 seconds, and then backwards 50 feet in the next five seconds. Now if they tell you to do this two times, the speed remains the same so in order to do this twice in ten seconds, you have to cut the distance you travel in half to 25 feet. That will allow you to go forward and backward twice (cycles) in ten seconds but the distance (wavelenght) for each cycle is half as long.
Put another way, if someone tells you to drive your car forward and backward one time (an equal distance forward and backward) at a specific speed in ten seconds, you will drive forward a certain distance, lets say 50 feet in 5 seconds, and then backwards 50 feet in the next five seconds. Now if they tell you to do this two times, the speed remains the same so in order to do this twice in ten seconds, you have to cut the distance you travel in half to 25 feet. That will allow you to go forward and backward twice (cycles) in ten seconds but the distance (wavelenght) for each cycle is half as long.
Basically, it is the distance covered by the signal, during one cycle. The lower the frequency, the more time that takes, so the wave front travels farther. (The distance traveled is the name of the band.)
majoco
Stirrer
A radio wave travels at the same as the speed of light, 299,792,458 metres per second - lets call it 300,000,000 metres per second.
The old way of expressing frequency was cycles per second, and we had kilocycles and Megacycles, kilo = 1000, Mega = 1million.
A wavelength is the length of one cycle, the distance from the start of the first cycle to the start of the second.
A frequency of 1Mc/s has 1 million cycles in one second, therefore one wavelength is 1 millionth of 300,000,000 metres = 300 metres.
The easy way to find the wavelength in metres from the frequency is to divide 300 by the frequency in Mc/s (or MHz now!) and the opposite for wavelength to frequency, frequency in MHz = 300/wavelength in metres.
So the middle of the 49m shortwave broadcast band is 6MHz. Divide 300 by 6MHz and you get 50 metres! Close enough!
The sun is 150 million kilometres away. How long does it take the light from the sun to get to earth.....?
The old way of expressing frequency was cycles per second, and we had kilocycles and Megacycles, kilo = 1000, Mega = 1million.
A wavelength is the length of one cycle, the distance from the start of the first cycle to the start of the second.
A frequency of 1Mc/s has 1 million cycles in one second, therefore one wavelength is 1 millionth of 300,000,000 metres = 300 metres.
The easy way to find the wavelength in metres from the frequency is to divide 300 by the frequency in Mc/s (or MHz now!) and the opposite for wavelength to frequency, frequency in MHz = 300/wavelength in metres.
So the middle of the 49m shortwave broadcast band is 6MHz. Divide 300 by 6MHz and you get 50 metres! Close enough!
The sun is 150 million kilometres away. How long does it take the light from the sun to get to earth.....?
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majoco
Stirrer
Yup! 
majoco
Stirrer
What's happened to the OP - RTL169Radio - does he still not understand? Or what is a bit too technical - above his pay grade?
Imagine a bouncing basketball. Try dribbling it from 3 feet as opposed to 1 foot and take note of how many times it bounces and the relationship to the distances. Same concept.
N8IAA
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