Hello every one............
I am using HT640 to wireless transmit instructions to a small robot but i want to extend the range of the signal, so i want a circuit that amplifies the signal of transmition.

Frequency: 435MHz

It is actually an RF remote controller.

Thank you.....

 

Hello,

A better antenna might help more than an amplifier.
An amplifier will also introduce some noise.

Bertus

 

I don't know what licencing regime you are under where you are Bob, but it's likely that 435 MHz is within the 70 cms amateur band. If you obtain a licence you would be able to happily and legally transmit on several Watts rather than the few milliwatts that licence exempt devices tend to allow.
As bertus says though, look at optimising your antenna systems before you consider more power. 70 cms antennas naturally will tune up very well for this purpose.

 

The HT640 does not provide any RF output. It provides an encoded data output that is fed to a transmitter from pin 8. Any transmitter tuned to your desired frequency should work.

 

The antenna that you linked to is a two band antenna, which means that it is a compromise on both bands. Unless you have a need to transmit on both bands, you would be better off with an antenna specifically for the 435MHz frequency.

Two questions are important to deciding whether another antenna would be better than what you are now using. 1) What are you using now and what is its gain? 2) What is the gain of the new antenna?

Antennas for 435MHz are small because the wavelength is short, and so can be home built quite easily.

 

You will also have a much higher signal strength with a directional antenna. The more common variate is the yagi antenna.

 

Your transmitter is most likely Part-15 compliant.
A better receiver and better antennas on both ends would be the best answer in the long run.

If this robot is for hobby use an Amateur Radio license would be fine.
If your robot is for business / industrial use there are a number of radio services you can use an RF link in with more power and legally.