antenna is gives poor signal

Yes, you can definitely buy a better OTA antenna online to assist in reception of different bands (UHF/VHF dedicated antennas). Moreover, with the current antenna you have, ensure that it is in the highest spot possible, and that the antenna itself is pointed toward the direction of your local channel towers. If the local channel towers are too far away or otherwise too weak in your area, you’d need to resort to either an outdoor antenna, or you would have to stream the local channels on a streaming device, granted that you have a stable broadband connection for streaming. 

Here, you can check the direction of your local channel tower (s) and their respective strengths: https://www.antennasdirect.com/transmitter-locator.html 

Check out the "Antenna Man" YouTube channel. Tyler has lots of great resources about antennas and optimizing off-air reception. 

@litzdog911 

Thanks for mentioning him. He is definitely a great resource for antenna assistance. I believe he also had a dedicated website for antenna recommendations based on one’s location.

http://www.antennamanpa.com/antenna-recommendations.html