For a single dish radio telescope we define the primary beam as the telescope's response on the sky as a function of angle. What this means is that half way between the centre and edge of the primary beam, a radio source with a flux of 1 Jy will be observed to have a flux of 0.5 Jy. This response is circular i.e. it is a function of angular separation, and is not dependent on altitude/azimuth. The full-width of this response is typically written as:
where are the primary beam width in radians, observing wavelength and dish diameter.
As for the big ear telescope, it is obviously not a parabolic reflector or Gregorian offset like the Lovell or Greenbank telescopes (www.naapo.org/W8JK/Images/JDK097l.jpg). Since the secondary reflector is the important one in the determination of resolution, we shall use its dimensions, which are 103m long by 21m high.
The Wow! signal was received at 1420MHz which has a wavelength of 0.21m. Using the above equation, the response would not be circular, but 'fan-shaped'. The response would thereby have approximate dimensions on the sky of 0.12deg by 0.58deg (in azimuth and altitude respectively).
Caveats of this calculation are the non-circular reflectors, which means the actual shape of the telescope's response on the sky would not be Gaussian/symmetrical for that matter. But as for an approximate, angular resolution, 0.12deg by 0.58deg will suffice.
Further to this, if you can find the LST (local sidereal time) of when the Wow! signal was received, and assuming that the big ear telescope is pointing at the zenith (i.e. straight up), the spot the telescope was pointing to would be easy enough to derive based upon telescope latitude and LST. Enjoy!