No need to use any arrays for radio buttons
<INPUT TYPE=RADIO NAME=channel VALUE=1>C1
<INPUT TYPE=RADIO NAME=channel VALUE=2>C2
<INPUT TYPE=RADIO NAME=channel VALUE=3>C3
<INPUT TYPE=RADIO NAME=channel VALUE=4>C4
<INPUT TYPE=RADIO NAME=channel VALUE=5>C5
In your PHP, $channel is set to the selected value, e.g.
if C3 was selected : $channel=3
Hope this helps.