Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
I think you mean the amplifier at the antenna end of the transmission line. DC is sent up the cable and separated out with an inductor. There is a capacitor that separates out the amplified signal.
If you don't have the amplifier on the antenna, which is more
probable case depending upon your location, the antenna is a
passive device and does not require a power source.
It absorbs power from electromagnetic waves propagating
throught the air, and converts the energy into electrical (RF)
voltage or power.
S. H.
thanks.. wanted to get clarification for passive devices only..
However, still confused...
These EM waves which you are talking about should lie in which band of frequencies.. the radio frequency or they can lie in any frequency band.. (and then depending on the circuit it will convert particular EM waves into electrical signals) ?
There is something like -- size of an object should be comparable to the wavelength.
So if we are talking about TV antenna on a roof top, we expect it to absorf RF of EM waves.. and hence there will be a minimum and maximum size of the antenna length which we can make.. Is it correct ? If the antenna size doesnt lie between these two extremes theoretically it should not work ?
Antenna can be of "resonnant" and "non-resonnant" type. TV antenna is resonant. It is selective.
Antenna elements dimensions depend on frequency. But overall antenna dimensions depend ollso on parameters like wanted gain and directivity.
Try to search forum on this topics and you will find a lot of answers. Try some book.
I would also recommend 007 to read some books on antenna.
Antenna dimension is heavily dependent on wavelength.
But, it is not simple to generalize or set a limit for the dimension.
TV antennas usually work aroung 1/2 wavelength.
Rhombic antennas can be longer than 10 wavelength, while your
small portable AM radio contains a very small antenna of less than 1/10000
wavelength. It all depends purpose, cost, design, etc.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
