A little warning before we start: this isn’t going to be a long article full of math and equations that most people will never be able to understand. It’s my goal here at The Solid Signal Blog to provide information that the average person will find useful. Sometimes that means simplifying things a little bit or glossing over details. I want to help you choose the right equipment and feel confident in what you have and how to use it. I know there are a lot of sources for PhD-level information when it comes to RF engineering, and if that’s what you’re looking for I think that’s great. Realistically, this isn’t that.
We use the term “electromagnetic spectrum” for all the kinds of electrical energy that can travel from place to place. This includes everything from sunlight to X-rays to radio and TV broadcasts. It doesn’t include vibrational energy like sound, or kinetic energy like a football traveling through the air.
The idea of the electromagnetic spectrum is based on two simple concepts. The first is that energy does travel from point to point. If it didn’t, there would be no life on Earth since the sun’s energy would not have warmed up the planet enough to support life.
The second concept is that the way we experience that energy is based on a very specific thing about it, which we sometimes call frequency and sometimes call wavelength. We “see” visible light but we don’t see X-rays or broadcasts. We use certain types of energy for local broadcasts like FM radio and cell phones, and other types to receive signals from light-years away.
Perfect Pitches
Albert Einstein, best known for being the only physicist most people can name, proposed that electromagnetic energy can be treated as particles sometimes and waves sometimes. Obviously this makes zero sense to most people but that’s how physics works. If we want to treat energy like it’s sand and measure how much of it is coming at us, we can do that. And if we want to treat it like the waves in a pond and watch how it travels from a single point, we can do that too. I know, it’s hard to wrap your head around. Luckily we’re not going to talk about particles at all in this article. We’re going to talk about waves.
An energy wave has three characteristics. The first is speed and we’re not going to talk much about that. This kind of energy does slow down in the air compared to its speed in space but the difference isn’t that important to us.
The second characteristic is amplitude. We’re thinking about waves here so amplitude is the height of the wave. That also isn’t really important to us.
That leaves frequency. The frequency of the wave means how many waves actually happen in a fixed period of time. We use the word hertz to describe one full wave per second. The more waves per second, the more we use the metric system to describe it. Most broadcasting on earth uses waves somewhere between .5 and 5,000 megahertz, or million waves per second. Satellite communication uses waves in the gigahertz (billion waves per second) range, while visible light is measured in the terahertz (trillion waves per second) range.
The most important thing to know about frequency is that, for the most part, energy at one frequency doesn’t interfere with energy at another frequency. That simple fact makes it possible to have all the radio stations, television stations, cell phone towers, and all those things that we have. If that weren’t true, then you’d only be able to broadcast one thing, ever. It also would mean everything was the same color, and a lot of other unpleasant things. But we don’t have to worry about that. You can use whatever frequency you want, as long as it makes sense for you to do it and the law allows it.
That’s right, the law. Every country has laws that govern what frequencies can be used and for what purposes. If those laws weren’t there, anyone could broadcast anything at any time. Since only one broadcast can exist on any specific frequency in a specific place, that would lead to all sorts of problems and no one would be able to receive anything.
Frequency is one way to describe the overall size of a wave measured over time. The other is wavelength. If you look at the photo above, you see that as the frequency gets higher, the waves themselves get narrower. So, we can talk about different waves in terms of their actual physical size and it’s similar to talking about their frequency.
The waves used for communication really vary enormously in size. Believe it or not, the waves used for AM radio are around 600 feet wide! Those used for satellite broadcasts are about .4 inches. Broadcast TV is in the middle, where the waves are about 6 feet wide for low channels and as small as 20 inches wide for the high channels.
Wavelength and frequency match up. The higher the frequency, the smaller the wavelength. There’s only one frequency for each wavelength and one wavelength for each frequency.
We care about frequency when we’re talking about the technology for broadcasting signals. In order to broadcast at a specific frequency (or wavelength) we need to create a certain number of waves every second. So the frequency is important in that case.
We care about wavelength when we’re talking about the technology for receiving signals. The antenna we use to receive a signal should be the exact size of the wave, or an even fraction like half, one-quarter, or one-eight. The less exact the antenna size is, the less effective the antenna will be.
Now realistically we tend to use those words pretty much interchangeably. We can do that, like I said, because they always link up. If you’re broadcasting on a frequency, you might also say you are broadcasting on a wavelength and people would generally know what you’re talking about. For the most part we tend to use frequency more than wavelength for whatever reason, even when we’re talking about antennas and reception. But that’s ok, as long as everyone understands each other.
If you’re looking for an antenna, a receiver, or anything else in the world of RF engineering, you’ll find what you’re looking for when you shop the great selection at SolidSignal.com. You’ll also find the most helpful and knowledgeable people when you call us at 888-233-7563 or fill out the form below.
The post What’s the difference between frequency and wavelength? appeared first on The Solid Signal Blog.
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Let’s start with the electromagnetic spectrum
We use the term “electromagnetic spectrum” for all the kinds of electrical energy that can travel from place to place. This includes everything from sunlight to X-rays to radio and TV broadcasts. It doesn’t include vibrational energy like sound, or kinetic energy like a football traveling through the air.
The idea of the electromagnetic spectrum is based on two simple concepts. The first is that energy does travel from point to point. If it didn’t, there would be no life on Earth since the sun’s energy would not have warmed up the planet enough to support life.
The second concept is that the way we experience that energy is based on a very specific thing about it, which we sometimes call frequency and sometimes call wavelength. We “see” visible light but we don’t see X-rays or broadcasts. We use certain types of energy for local broadcasts like FM radio and cell phones, and other types to receive signals from light-years away.
Particles and waves
Perfect Pitches
Albert Einstein, best known for being the only physicist most people can name, proposed that electromagnetic energy can be treated as particles sometimes and waves sometimes. Obviously this makes zero sense to most people but that’s how physics works. If we want to treat energy like it’s sand and measure how much of it is coming at us, we can do that. And if we want to treat it like the waves in a pond and watch how it travels from a single point, we can do that too. I know, it’s hard to wrap your head around. Luckily we’re not going to talk about particles at all in this article. We’re going to talk about waves.
An energy wave has three characteristics. The first is speed and we’re not going to talk much about that. This kind of energy does slow down in the air compared to its speed in space but the difference isn’t that important to us.
The second characteristic is amplitude. We’re thinking about waves here so amplitude is the height of the wave. That also isn’t really important to us.
That leaves frequency. The frequency of the wave means how many waves actually happen in a fixed period of time. We use the word hertz to describe one full wave per second. The more waves per second, the more we use the metric system to describe it. Most broadcasting on earth uses waves somewhere between .5 and 5,000 megahertz, or million waves per second. Satellite communication uses waves in the gigahertz (billion waves per second) range, while visible light is measured in the terahertz (trillion waves per second) range.
What to know about frequency
The most important thing to know about frequency is that, for the most part, energy at one frequency doesn’t interfere with energy at another frequency. That simple fact makes it possible to have all the radio stations, television stations, cell phone towers, and all those things that we have. If that weren’t true, then you’d only be able to broadcast one thing, ever. It also would mean everything was the same color, and a lot of other unpleasant things. But we don’t have to worry about that. You can use whatever frequency you want, as long as it makes sense for you to do it and the law allows it.
That’s right, the law. Every country has laws that govern what frequencies can be used and for what purposes. If those laws weren’t there, anyone could broadcast anything at any time. Since only one broadcast can exist on any specific frequency in a specific place, that would lead to all sorts of problems and no one would be able to receive anything.
Yeah so what about wavelength?
Frequency is one way to describe the overall size of a wave measured over time. The other is wavelength. If you look at the photo above, you see that as the frequency gets higher, the waves themselves get narrower. So, we can talk about different waves in terms of their actual physical size and it’s similar to talking about their frequency.
The waves used for communication really vary enormously in size. Believe it or not, the waves used for AM radio are around 600 feet wide! Those used for satellite broadcasts are about .4 inches. Broadcast TV is in the middle, where the waves are about 6 feet wide for low channels and as small as 20 inches wide for the high channels.
Wavelength and frequency match up. The higher the frequency, the smaller the wavelength. There’s only one frequency for each wavelength and one wavelength for each frequency.
Here’s where we care
We care about frequency when we’re talking about the technology for broadcasting signals. In order to broadcast at a specific frequency (or wavelength) we need to create a certain number of waves every second. So the frequency is important in that case.
We care about wavelength when we’re talking about the technology for receiving signals. The antenna we use to receive a signal should be the exact size of the wave, or an even fraction like half, one-quarter, or one-eight. The less exact the antenna size is, the less effective the antenna will be.
Now realistically we tend to use those words pretty much interchangeably. We can do that, like I said, because they always link up. If you’re broadcasting on a frequency, you might also say you are broadcasting on a wavelength and people would generally know what you’re talking about. For the most part we tend to use frequency more than wavelength for whatever reason, even when we’re talking about antennas and reception. But that’s ok, as long as everyone understands each other.
Need help with broadcasting or reception?
If you’re looking for an antenna, a receiver, or anything else in the world of RF engineering, you’ll find what you’re looking for when you shop the great selection at SolidSignal.com. You’ll also find the most helpful and knowledgeable people when you call us at 888-233-7563 or fill out the form below.
The post What’s the difference between frequency and wavelength? appeared first on The Solid Signal Blog.
Continue reading...
