i have bought all the components to make radio transmitter and receiver.but i am week at basics i dont know which factor cause effect on transmission.i mean which decides transmission range

 

i have bought all the components to make radio transmitter and receiver.but i am week at basics i dont know which factor cause effect on transmission.i mean which decides transmission range

Everything

decides the "range". Frequency, Output Power, Receiver Sensitivity, Antenna Height, Antenna Gain, Terrain Profile, Type of Data, Bandwidth, Modulation Technique, . . . . . (have I left out anything else? )

It's difficult to answer your question at this stage. What do you want to transmit? What is the expected Range? If this is known, then we have a starting point to proceed from.

Ramesh

 

my transmitting distance is just 2 or 3 meter.i am new to this.so first want to make a led on and off by switch via radio waves.

 

You might want to start by researching which frequency bands would support the legal pursuit of that activity. You can't just start spewing RF into the "ether" and expect to get away with it.

You might also want to reveal your location which will have an effect on the legal issues surrounding the construction and operation of a transmitter.

 

i dont know which factor cause effect on transmission

The local police will be one factor . They will shut down your transmitter unless it operates legally.

 

my transmitting distance is just 2 or 3 meter.i am new to this.so first want to make a led on and off by switch via radio waves.

I guess that you are from India. Legally, you are permitted such activities only on the 2.5 GHz free band. With your background, it will be not easy to build a transmitter that meets the legal requirements. I'd suggest that you go in for a ready made unit, something like
Shop for remote LED on off on Google

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Wireless Remote Led ...
Rs. 481.37
EachBuyer.co...

Ramesh

 

I guess that you are from India. Legally, you are permitted such activities only on the 2.5 GHz free band. With your background, it will be not easy to build a transmitter that meets the legal requirements. I'd suggest that you go in for a ready made unit, something like
Shop for remote LED on off on Google

i want to be engineer not one who buy all components available and make some thing

 

thanks you all

 

i want to be engineer not one who buy all components available and make some thing

I think we understand that, but you might be going about it in the wrong way. Wanting to be an engineer is a good start, but starting with a strong understanding of basic physics, mechanics, and mathematics is essential. Tinkering here and there is a very inefficient way to get there. We are here to help, but we ask that you meet us halfway by doing basic research and investigation on your own, asking coherent and precise questions with appropriate documentation, and avoiding "text-speak".

Not using correct spelling, capitalization, and punctuation makes you seem illiterate, and impressions matter a great deal in the engineering community. Certainly any employer will use these things to measure your competence -- especially if lives are on the line. My views may seem harsh to you, but I am offering the benefit of a half century career in engineering because I think if you take them to heart, you may derive some benefit.

 

Thank you,sir. I don't do this mistakes again.

 

As others have mentioned, there are many, many variables that go into range. Output power, impedance matching, antenna resonance are a few basic ones. Weather, terrain, and humidity are a few environmental factors that affect transmission range. It's really impossible to even mathematically predict, but if you would like to research it more I have lecture notes and simulation software you can use.

 

fnd one of the local ham radio clubs, there should be someone there that can help you with both the legal and engineering problems. if you have to transmit on the 2.5 ghz range, that is very hard to make stuff for even with an education in electronics.