San Francisco is an ATSC 3.0 market. ATSC 3.0 should provide a clearer image than ATSC 1.0
Does your TV accept ATSC 3.0 signals?
If not, you might consider an ATSC 3.0 tuner. The SiliconDust HDHomeRun Flex 4k ATSC 3.0 is $200 on Amazon.
https://www.amazon.com/SiliconDust-HDHomeRun-Flex-ATSC-NextGen/dp/B092GCN9NL
Your best bet is to get an SiliconDust HDHomeRun box. You can get the antenna version or the cable-card version for your cable TV.
This one even support 4K ATSC 3.0 TV over the air. So if you are in a major city they are probably already broadcasting in 4K. This is $200 and needs a network connection so you can put it anywhere in your house, Doesn't need to be close to your server.
https://www.silicondust.com/product/hdhomerun-flex-4k/
https://www.amazon.com/SiliconDust-HDHomeRun-Flex-ATSC-NextGen/dp/B092GCN9NL
This is the cable-card version where you get a cable-card from your cable company and then you have full access to your cable TV to pull it in to Jellyfin. This is $150.
https://www.silicondust.com/product/hdhomerun-prime/
https://www.amazon.com/SiliconDust-HDHomeRun-PRIME-Cable-3-Tuner/dp/B004HKIB6E/