I have been told it has to be able to receive vhf/ uhf/ hdtv/ dtv
The "must be able to receive HDTV/DTV" is just marketing garbage. All antennas can do this if they can receive the carrier frequency. Part of antenna design determines the frequencies it can receive. What is contained on those frequencies - digital or analog, high definition or standard definition - makes zero difference. So you're just looking for an antenna that can receive TV broadcast frequencies, which are in the VHF or UHF band.
A big thing you should investigate is WHERE your TV channels are being broadcast from. Are they coming at you from all different directions? Then you will need an omnidirectional antenna (or a unidirectional antenna with a rotator motor that you can adjust to "point to" a specific transmitter). If they are coming at you from one direction, then you want a unidirectional antenna. That is the case at my place. All the TV stations broadcast from one place - on "Lookout Mountain" - so I just aimed my antenna at that place and I'm done with it.
Outside placement, up high, is best. But also the most expensive to implement. And you should include lightning protection. Inside, in your attic, is second best. Assuming you can point the antenna (if unidirectional) on the correct compass bearing. And also assuming that you don't have that foil sheathed insulation in the attic that can block signal (if you have this insulation in your attic, you probably have it in the walls of your house too). Lower, in your living area is third best. Actually, it's never best, it's always worst, but it may be your only option. Or your incoming signals may be strong enough that you don't need anything better than inside antenna placement.
Signal amplifiers can help, but if your problem is poor signal at the antenna, probably not. I have found amplifiers work better when you have a good signal coming in, but then you run that through a multi-way splitter which will attenuate the signal. An amplifier can help negate the splitter losses. Each time you split the signal, you cut it in half. So a four-way splitter gives you 1/4 strength signal at each of the outputs. Or a two-way splitter that feeds a second two-way splitter also gives you 1/4 signal at the outputs. Use splitters only when truly needed.
If it is true that your problems are "poor reception because of terrain" then your biggest improvement (if you can get any improvement at all) will probably be a high placed outside unidirectional high gain antenna. This can get expensive, so you might want to play around with temporary mounting to see what works and what doesn't. e.g., you can drag an antenna up into your attic and prop it up with cardboard boxes to test if it works OK up there before jumping to more expensive outside antenna masts, requiring lightning protection, etc. If it works in the attic during testing (be sure to point it on the correct compass bearing if your stations are broadcast like that), then you can add some type of formal attic mount. To mount mine in the attic, I just hung it upside down (the antenna doesn't care!) from the rafters and secured it's short mast with U-bolts. Antennas, when placed in attics, tend to grow to about 3x their original size once you're up there and trying to maneuver the thing around. So be wary and don't step through your drywall ceiling and end up in your living room as you negotiate the install.
