Gary, have you considered this:
https://www.ebay.com.au/itm/Antenna-...frcectupt=true
And this:
https://www.ebay.com.au/itm/5dBi-Ant...frcectupt=true
Antenna goes to roof of obs, USB stick into comp/lap in obs. You will need some coax cable to connect WiFi adapter to antenna.