Hi Robby,
Your TV fool map gives you a some possibilities. First, looks like magnetic 240 will yield you ABC,NBC,CBS, PBS (KRIN) and possibly ION from Cedar Rapids in addition to another Iowa Public television signal (KIIN)
I wouldn't suggest a DB8e for this application. A quality antenna it is, however you need hi-vhf capability (channels 7-13) in addition to UHF support. The DB8e is a UHF design.
I would suggest a
Winegard HD 7698P orientated at magnetic 240 for reception of Cedar Rapids. Test reception with antenna fed directly into a single TV before determining you need a preamp.
If you want to try for Madison's signals, the DB8e is appropriate as all Madison's signals are UHF that you can attempt to receive. Orientate the DB8e towards magnetic 78. Test reception without preamp to see what level of reception you have of the Madison signals. You should see ABC, CBS, FOX and PBS. NBC and the CW are very weak and may not be reliable.
If you want to go an option that gives you both markets, you can buy both antennas mentioned above. Mount them on your roof with the DB8e at the top of the pole with the 7698 mounted at least 4' below, make sure you choose a location with the clearest pathway to both sets of transmitters.
Run separate leads of coax inside to an A/B switch
http://www.homedepot.com/p/GE-A-B-Sw..._src=17588969#. This will eliminate a need for a rotor and give you two different sets of channels!
There is a last option which would give you a single coax running into your home. As above install a DB8e to magnetic 78, below it mount an Antennacraft Y10-7-13 at magnetic 225 (instead of a 7698P). Purchase an Antennas Direct EU385CF-1s combiner . The EU385CF-1 has a specific UHF and VHF inputs. Input the Y10-7-13 coax into the VHF coax input, while connecting the DB8e to the UHF side of the combiner This arrangement ought to give you the above Madison signals as well as ABC and NBC from Cedar Rapids off of one run of coax into your home. You may see KIIN (PBS) from Waterloo as well.
The trade off is that likely CBS and the stronger PBS (KRIN) from Cedar Rapids would be lost.
Many options for you to decide!
Best of luck!
P.S. For sake of this write up, I ignored WHBF RF 4 CBS from the Quad Cities. While reception may be possible, reception of CBS programming is much easier caught on Madison and Cedar Rapids' broadcasts.