No, you do not need a separate HDTV antenna unless you are using the antenna to get your channels. If you have cable TV, then the antenna is not necessary.
HDTV does require an antenna. However, if you are using an antenna on your existing television there is no need to go out and purchase another. HDTV's do not require a special antenna.
You will need an antenna and a HDTV with a tuner built in. You will then get your local channels in HD.
You would need an HDTV antenna when you can get all of your channels and when you get bad signals. This is when the picture don't play clearly and it has bunch of lines.
HDTV antenna online from Amazon has really great service. They also sell really good prices for HDTV and antenna that would help you since you broke your antenna.
If the TV is a HDTV and there are HDTV stations near by you won't need a converter box.
HDTV, High Definition Source (HD Cable Box, Antenna, HD Satellite Box), the cables to connect them.
You would need a HDTV tuner when you don't have cable. You would need a tuner when you can't get a good reception from the antenna and when you don't have cable.
You would need to run the Cable co-ax into a splitter switch, and connect the HDTV antenna to the other side.
There are many online shops that sell outdoor HDTV antenna. Amazon.com is one of online shop that sell outdoor HDTV antenna with any kind of models. You can visit www.amazon.com.
A VHF/UHF antenna is the correct one for HDTV. If you are using a indoor antenna, the amplified ones are better.
You don't have to purchase a new HD TV antenna. You can purchase any type of antenna and it will work on a HDTV as well as any other television. The television is not the issue.
I am replying to your question about the need of a HDTV antenna and where to get one, any electronic stores i.e.: BestBuy, future shop, radio shack, the source if you cannot find it there go to to more of a specialty TV store they are bound to have one.