airdrop on imac does not pickup my iphone 7/8.

I have an IMAC - late 2012 model running on OSX 10.9.5. Airdrop on IMAC is not picking up my iPhone 8 or 7. Done checked all the settings on both devices. I have also paired both devices in Bluetooth. However when connecting the iPhone on the IMAC's bluetooth screen it gives the following error message "Network is unavailable - Make sure network access is enabled". Could this be the reason why airdrop on IMAC does not pick up the iPhone devices? and how do i fix this? thx