There may be more than one reason for needing to adjust the antenna.
1 - Viewable stations lie in various directions. (you may need to rotate the antenna)
2 - Several stations are broadcasting on VHF channels. (you may need to adjust the length of the dipole rods)
3 - The building unpredictably attenuates and reflects signals. (you may need to change the location of the antenna)
Adding more complexity at the antenna, ex. 'fine tuning' controls or variable gain amplifiers, will add to the list of reasons the antenna would need attention at each channel change.
Ideally I would advise a small exterior antenna such as the RCA ANT-751 or Antennacraft AC-9 aimed south and slightly east. However, a simple, basic set of 'rabbit ears' ex. http://www.channelmasterstore.com/CM..._p/cm-4010.htm
will offer a you a very good lineup of programming if you home construction does not use lots of metal. Metal siding, stucco wire, steal studs and insulation foil are examples of materials that will cause indoor antennas to fail.