For Analog broadcast"
Original Baron Antenna is good. It is design to be used for VHF frequencies and with almost circular detection capabilities as can be seen by its Long Dipole and single director parts.
If you want to venture on Digital broadcast:
Try considering the Skytv+ of Abscbn...you can replace its antenna with outdoor antenna designed for UHF frequencies. ( Shorter Dipole ).
Things to consider for the antenna.
1) Location - VHF and UHF frequencies works on line-of-sight concept. So it is always better to have an outdoor antenna. Always check any blocks in between your antenna and the transmitter.
2) Type of Antenna -
a) VHF or UHF (analog broadcast works on VHF/ lower UHF freq but Digital broadcast works on higher UHF frequency.
b) Directional ( if you are away from the Transmitters) or omnidirectional type if you are within the area where the transmitters are located.
It actually depends on your needs and location.
Note : Antenna helps only in receiving the signals from the transmitter. It has nothing to do with HD contents or not. Maybe it is just me, but i was a bit confused what does "HDtv Antenna" mean? Antenna for HD capable tv?
Hope it helps..or lalong nagpagulo...