Channel impulse response in freqency domain I have a doubt about DFT matrix and channel impulse response.

Let $h$ is a channel impulse response , $F$ is a DFT matrix. IF I take a product. I got: 
$$ F* h=\tilde{h}$$

$\tilde{h}$ is a frequency response of the channel, isn't? or channel impulse response in frequnce domain
You are right. If you have MATLAB, you can do a little experiment to double check yourself:

h = randn(100, 1);     % make some random impulse response
F = dftmtx(length(h)); % make the DFT matrix (100-by-100)
abs(fft(h) - F*h)      % this number should be small