you have nice copper wire inside coax cable.
copper core of your tv coax will probably do just fine as an antenna. just strip it, cut it and solder it.
ok i will so in the datasheet of my RFs it says antenna should be : Attenna:25cm Single core wire or mutil‐core wire
and a remark :
VCC voltage module operating voltage and good power filtering;
A great influence on the antenna module reception, preferably connected to the
1/4 wavelength of the antenna, generally a 50 ohm single‐core wire, the length of
the antenna 315M approximately 23cm
Antenna position has also affected the reception of the module, the installation,
the antenna as possible straight away from the shield, high pressure, and
interference source; frequency used to receive, decode and oscillation resistor
should match with the transmitter.