Is there any good indoor HD over the air antenna?

There is no need for a special "digital" or HD antenna. There is no difference between analog signals and digital signals as far as the antenna is concerned. Most places who push a digital antenna either don't understand or are simply trying to increase their sales and profits. Just get a decent antenna. Most of the amplified indoor antennas are extremely cheap and the amplifier in them usually causes more problems. Note the other answer about this. If you use an indoor antenna, put it in front of a window if you can. Also put it as high as possible. Try to keep it out of places where people walk past or hang around. People's bodies reflect, attenuate and change the RF pattern causing changes in the reception.

Your body will cause a change in the capacitive coupling and therefore the tuning of any indoor antenna which you can approach resulting in the kinds of problems you cite. They cannot be avoided, sorry. I recommend that you put a log periodic type antenna in your attic and point it toward the TV transmitting antennas. In most cities the TV transmitting antennas are usually located in the same general area so that pointing the antenna at one TV transmitting antenna will get them all. For instance, in Dallas all but a few of the TV stations have their antennas on towers on Cedar Hill south of town. If you live near a city a low gain antenna with few elements will usually do the job just fine. In fact, installing a high gain antenna can often cause co-channel interference (wavy diagonal lines) from TV stations on the same channel in another city. If you cannot put an antenna in the attic I would tape or pin a folded dipole for the FM band (Radio Shack) to the ceiling. That keeps it away from the influence of the people in its vicinity and it is cheap. Orient the antenna broadside to the TV transmitters. If there is one channel in particular that you prefer you can prune the antenna to that frequency by using the formula L = 468/F where L is the length in feet and F is the frequency of the TV channel in MHz. Be sure to allow for connecting (shorting) the end wires of the folded dipole. You could also put a small UHF corner reflector on top of a bookcase, in your attic or on a balcony and do pretty well too. Next year the TV channels will vacate the VHF band and move to UHF so you will be ready for that when it happens. There are lots of possible ways to solve this problem. These are just a few simple ideas. Good luck and 73 from the Fisherman

Apparently your location is close enough to the TV transmitting antennas in that you can use an indoor antenna. Any kind of signal bounce or reflections within the household will tend to cause pixel breakup and lost of signal. Your best bet to avoid this is to mount an external antenna pointing in the proper direction to avoid these signal mishaps. Good Luck.