The greater the amplitude of a given frequency of light hitting an antenna the greater the induced speed of electricity in the antenna? Reply in simple english please.
No, that applies to hitting golf balls, but not to antennas.
The speed of the wave in an antenna is comparable with the speed of light and it depends on the dimensions of the wire but not on the amplitude of the signal.
Then how does the energy from the amplitude of the light transmit onto the antenna? I appreciate the clear writing.
A stronger signal field strength results in a larger output signal from the antenna.
So, if the field strength is varying like a sinewave then a stronger field will produce a bigger sinewave output than a weaker one.
But the velocity of the wave in the antenna stays the same. Weak signals travel just as fast as strong ones in space and in an antenna.
the energy of light doesnt transfer onto an antenna
you have a little confusion I suspect
Tho an electromagnetic wave is composed of moving photons, those photons are are not visible light photons.
An electromagnetic E-M (radio wave) wave moving through space ( the air etc) will induce an electrical current into the metal wire/rod of the antenna ( or any other conductive surface it encounters). To get maximum efficiency of energy transfer (induced energy) the antenna length is cut so that it is resonant with the frequency of the radio wave.
that length can be determined by the formula wavelength = speed of light / frequency
an easy way to work that out for MHz of frequency is ....
300 / 100MHz = 3 metres (wavelength)
rarely are full wavelength antennas used more normally a halfwave one is used so you would divide that 3metres by 2 and end up with 1.5 metre for a halfwave antenna
Maybe transfer is the wrong word. When I wrote light I meant EMR, expecially radio waves. Why does the length of the antenna change the resonance of th antenna? So if the desired signal wavelength is 3 metres then what would be the best length for the antenna? I appreciate the help!
Thats OK :) we all have to start some where
3 metres is the wavelength of a frequency of a 100 MHz ( in the middle of the FM broadcast band 88 - 108 MHz) radio wave.
I dont know what country you are in ? maybe you have the 27 MHz or 476MHz citizen bands
( also known as PRS ) lets, using the formula I gave you above, work out the wavelengths for each of those frequencies.
27MHz is at the high end of the High Frequency (HF) band
300 / 27MHz = 11.11 metres wavelength
476 MHz is around the middle of the Ultra High Frequency (UHF) band
300 / 476MHz = 0.630 metres = 63 cm wavelength
when the antenna is the same length as the wavelength of the radio wave its at its most resonant and will have the greatest amount of energy induced into it
To use a non radio wave analogy, but still the same principle, think of an opera singer who breaks a wine glass with her singing. The wine glass because of its size and construction will have its own resonant frequency. Now the singer can sing all sorts of musical notes at the glass, most wont have any effect as their frequency is too far from the resonant frequency of the glass. but as the singers musical tone approaches the resonant freq of the glass it will start to vibrate and if the amplitude ( loudness) of her singing plus producing the correct tone is just right it will cause the glass to vibrate so much it will shatter.
At that time the frequency of the tone ( note) being produced by the singer and the resonant frequency of the glass are the same and the glass absorb the maximum amount of energy.
does that help ?
Yes it does help me a lot and there's always more questions so answer if only feel like it. I don't understand how a sine wave passing by an antenna at a strange angle can induce a current that can be decoded..
OK back to antennas and angles and things.....
You may have noticed as you look around that you see antennas orientated in one of normally two different polarisations, horizontal and vertical.
If the transmitting antenna is vertically polarised so will the receiving antenna. If the transmitting antenna was say, vertical and the receiving antenna horizontal, there would be a substantial reduction in the received signal strength because of the mismatch.
There's one that says VP and it seems to be HP to me. I notice that the VP antennas point up to the sky but in space there's no up. I'm learning so much but I don't know what I could do in return for helping me so much.
I did google Mr Uda Yagi and he seems to suffer from a severe case of split personality:Yagi antenna ( NOTE the capital Y), the name comes from Mr Uda Yagi, a Japanese guy who invented the Yagi system many years ago .. do a google search on his name.
.... As you go higher in frequency above 1000MHz there becomes a trade off between size and gain and it becomes more practical to use a dish type antenna
OK lets see how you go digesting that and what questions it generates :)
I know we are a long way from your original question and I hope thats has been answered successfully :) ...
Above is a pic of a local radio tower site, you can see there are a mass of antennas on it, and this was only the top 1/3 of the tower
Ah. Now I can go a little off topic. :)
When I saw this,
I wanted to say, "I wish I owned the tower". Well maybe a lot off topic, but there's money to be made if you own one. The Department of Transportation here in Kansas has a information page as an example.
Okay. Back to antennas.
So it comes down to me trying to build an ornithopter (although it doesn't resemble a bird very much). I need it to be radio controlled and I want the radio control system inside it to be well defined for this ornithopter. I'm also interested in radio control for other reasons but I'm wondering how I could get the receiver inside to receive signals from long distances. Is it best to use an antenna or no antenna at all? Of course info on anything close to that will be appreciated.
Of course info on anything close to that will be appreciated.
OK, I had to look up ornithopter just to confirm we were both on the same page haha
There are many good radio control systems out there. All the best ones these days use 2.4 GHz and are digitally encoded to avoid multi system intereference. Any respectable model hobby shop will be able to guide you into something suitable. As for range, well out to around 1km would be an approximate maximum.
yes, of course you will need an antenna, and again the systems for sale come with an antenna suitable for the unit you are remote controlling :)
Actually I meant that I want to aim towards learning about that, any attempt to help me will be appreciated but it would help me most to know about how I can make the radio control. Learning about antennas is very good.
I'm sort of a perfectionist and I want to make a simple but very effective remote control system that's specifically designed for the ornithopter. I have other reasons for wanting to know about it but I am very interested in radio control.
No one makes radio control systems themselves, everyone just buys the receiver modules and controllers. The electronics is much too complex for the average hobbiest to get into.
its a big enough job just buying the controllers and installing the module and servos into your model.
Maybe there's a simple and effective way, I don't mind if the controller is crude but I have difficulty being satisfied with a good radio system. I don't think of myself as much of a hobbiest (although I do do origami) but more of a want-to-be pioneer.