I tend to avoid omni-directional antennas because they lack the ability to reduce reception of multipath and they often have negative gain compared to a cheap UHF/VHF 'rabbit ear' style indoor antenna.
Your situation lends itself to a directional antenna because most directional antennas have reduced but usable gain to the rear. The two main groups of signals are 180 degrees from one another, so you're a prime candidate for using a directional antenna for reception in two directions at the same time.
The 70XX series is wide due to the length of elements tuned to the real CH-2 through CH-6 band. These type antennas may be appropriate if reception of the analog real CH-4 is imperative. If that's the case, you'll want to go large... As in HD7082P or HD7084P. My research into WIAV, real CH-4 came up with little information... it's unclear whether it's on the air or what type programming it may carry. It's licensed to ASIAVISION, INC.
http://www.rabbitears.info/facility_...168063#station and the CH-4 assignment is a construction permit, the current licensed channel is 58 with a construction permit on file for a digital transmitter on real CH-44
http://transition.fcc.gov/fcc-bin/tvq?list=0&facid=2962 The final bit of info found is that the FCC indicates the status as "LICENSED AND SILENT"
http://licensing.fcc.gov/cgi-bin/ws....cility_id=2962
I would suggest you try an RCA ANT-751 pointed at the NE group of signals. If your attic is a good receiving location, then you can expect both the NE and SW groups and may even see the strong signal from WMPT from the side.
The ANT-751 is small because it lacks elements for CH-2 through CH-6. If the attic fails as a good reception location the ANT-751 lends itself to wall mounting as well as conventional roof or gable mounting.
http://www.amazon.com/RCA-ANT751R-Ou...ywords=ANT-751