Two comments and answers here..
First; The ZIP code is used in the receiver for only one or two uses. First it is is used in conjunction with a look up table to suggest initial angles for setting up the antenna.. If it has any other effect on the receiver (I am not sure) it is the time zone.. You need not set the zip code at all.
HOWEVER: Local Network Stations, the ones you can pick up over the air that broadcast ABC NBC, CBS and so on, Those are "Spot Beamed" A single spot beam can easily cover a hundred zip codes even several hundred zip codes however but it does not cover all of the USA. Thus if, like me, you like watching "Person of Interest" or CSI____, You will be out of luck if you drive too far.
