plug your TV antenna in the back, if it makes a huge difference and you
start to hear more, your best getting a better/higher antenna.
Little telescopic antenna or window/ mag mount, are good for close car to
car comms or powerful broadcasts, but scanning is different. For the best
reception you need an antenna tuned for every separate frequency and there
are lots of frequencies on a scanner (impractical)
Get a ham antenna book it will show you how to build your own antenna, out
of bits of wire lolly sticks and tape, at a fraction of the cost.