let's see what it looks like from inside (thinking there's just no way this will work) and what do you know? It's nearly perfect (I mean signal strength of 91 - 98 on most channels). I was shocked!
Does that mean I can probably go ahead and bring my Dish 1000 inside, too?
Just kidding.
Your house isn’t amplifying your signal. You are experiencing Multi-path (bounced signals) and in this case, to your advantage, except for tripping over the outdoor antenna. Outdoors is better, but I’m betting, even though you said you had clear sky (assuming you meant clear line-of-sight to the towers) that you were experiencing Multi-path.
Do you live in a metro area?
Broadcast signals bounce off many things, such as buildings, hills, even walls inside your viewing room. Sometimes a bounced signal can be better than trying to receive the signal straight on and apparently, the location where you now have your outdoor antenna located and aimed is in a great location indoors to receive these Multi-path signals.
But Multi-path can be tricky. Multi-path reaching any antenna can send out of phase signals that can confuse the ATSC (Digital) chip set in the digital TV tuner. If the signal reaching the front of the antenna is not 2 to 3 times stronger than a bounced signal from the same station reaching the back of the antenna, the ATSC chip doesn’t know which signal to use, so it just keeps searching. You don’t seem to have this problem now with your antenna located and aimed the way it is now.
There are newer indoor antennas on the market that may very well get you the same reception; even combination indoor/outdoor antennas are designed to work with multi-path and the newer generation ATSC chips.
The fact that most designs on the market now were developed prior to the advent of much of the computer technology, software and algorithms in common use today has left open numerous avenues to improve upon tried and true designs and develop new ones. Additionally, recent regulations and standards opened new doors for antenna engineers to develop smaller antennas with greatly improved performance, power and aesthetics.
If you decide to try an indoor antenna, try several different locations and directions in the room. But I wouldn’t give up on outdoor yet. Many outdoor TV antenna designs in use now such as the Yagi (on many chimneys) have technology roots going back 30 years or more.
Buy the antenna from a source that will refund your full purchase price, no questions asked, until you find the antenna that will work for you and enjoy.