Dear all, above shows an AM (Amplitude Modulated Signal), I was just wondering how can I make the AM waveform to have a very low impendence so that it is able to transmit high power. One solution I tried is using an op-amp as buffer which can reduce impendence while keeping the shape of waveform same as before, but the problem is the op-amp cannot produce enough output power of lets say 10Watt to the antenna? So, I think I basically need an op-amp which can produce a good amount of power?

 

What You need is called a Transmitter, which must be "tuned" to a particular Frequency-Range.
Radio-Frequency (RF) Amplifiers are very specialized, they are usually not DIY friendly.
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Not to mention a license for the transmitter.

 

Once you have the license (10 watts is a lot!) you will need a linear RF amplifier. They are usually tuned for specific bands and specific input and output impedances. Not a good starter project because there are several complicated issues like efficiency, linearity, and intermodulation distortion that need to be addressed.

If this is for an industrial, scientific, or medial application you can use one of the ISM bands if you know how to make or buy equipment that stays within the allowable parameters of those services.

 

What is the purpose of transmitting that signal?

 

As LowQCab and DickCappels pointed out, you'll need a power amplifier. This is really a study in itself, as even that small amount of power requires a tuned circuit to optimize efficiency in terms of radiated power, antenna gain and direction/lobes if desired. Uncontrolled transmissions can cause spillover into adjacent frequencies and make life miserable for others. You might want to be judicious about where, how often and what time you use such a transmitter if you don't have a license. The FCC will certainly want to have a coffee and a chat about it sooner than later

 

A properly designed, and tuned, Antenna is far more useful and effective for increasing range,
instead of just cramming lots of heavy-Power in to a poor Antenna design.
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