characteristic impendence

I want do a matching for the power amplifier and antenna. how can I know the system characterristic impedence. I only have LCR meter.

LCR meter has no value in measuring impedance in your case.
To match an antenna to a power amplifier, you need a variable matching circuit which is a part of the amplifier. Such matching circuit usually matches a widely varying antenna impedance. A SWR indicator or a forward/backward current indicator is needed for the best match.

Refer to ARRL Amateur Radio Handbook os ARRL Antenna Book for details.

thanks for your detailed information.