The main group of Tv stations are to the , South West , put the antenna in/at a , South West , South , facing window or balcony door window , aim the antenna at about 200 degree magnetic compass direction.
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Building construction that has less impedement to Tv signals are , wood , wood or vinyl siding , standard flat asphault composition shingles.
The following is a Non Complete list of building construction that will do more impeding and blocking of Tv signals.
Metal beams , metal doors , metal siding , metal roof , metal backed insulation , stucko Wire , concrete , concrete blocks , bricks , rocks , and more.
Here is how to aim indoor and outdoor type antennas.
http://www.kyes.com/antenna/pointing/pointing.html.
Digital Broadcast Tuners can develop -Digital Glitches - that are not cleared out with simple channel scans.
Do Double Rescan ,
http://www.wchstv.com/DoubleReScanAlert.pdf.