Why TV signal is poor and how to rectify it ?

Bent cable:
Coaxial cable is flexible, but you should never have a sharp bend or kink in a cable. A kink anywhere in the run causes a mini reflection to occur, creating a second signal. This is the cause of the echo or ghosting effect and shadow.
Check all the coaxial cable leading to the TVs. Replace any sections where there is a kink.
Ghosting can occur as a result of problems with the metal connectors at the end of the cable.
If these connectors are improperly installed, or of poor quality, they can cause impairments to the signal.
Consider getting a qualified technician to check your connectors, or use pre-made cable lengths,