Airdrop

I have a mid-2014 Macbook Air on which Airdrop has never worked. Airdrop works perfectly on my iPhone 5 and iPad but neither can discover, or be discovered by, my Macbook. I have tried a lot of the online guidance to get it working today re bluetooth, wifi, contacts, firewalls, etc with no success although everything seems to be set up appropriately. All devices are using the latest software (iOS 11.2.6 and OSX 10.9.5). Has anyone solved a similar problem? I should add that when I go to Airdrop via Finder on the Macbook it doesn't show the Airdrop radar icon or the 'Allow me to be discovered by' option which I've seen in the online guidance screenshots so I can't specify 'contacts' or 'everyone'.