Why do some antennas claim they can receive HD broadcasts come with a coax output? can that carry an HD signal?

Any TV antenna will receive High Definition Broadcasts if the antenna is capable of receiving the frequency (channel) of the TV station being broadcast. The antenna doesn't care if the signal is analog or digital, high definition or standard definition if the signal is in the antennas channel range it will capture it. The down lead from the antenna is normally coax because coax has less loss than the old twin lead antenna wire. A TV signal looses strength as it travels over a wire. the longer the wire the more loss. Even twin lead antenna wire can carry an HD signal. All you are looking for from an antenna is to get a signal to the TV's tuner.

Even a coat hanger will get an HD signal if you are close to the station.

A high gain antenna will capture more signal and deliver more signal to the TV sets tuner than will a low gain antenna, BUT note there is NO such thing as a HDTV antenna.

The antenna must provide enough signal for the tuner. Give the tuner enough signal you get a picture, marginal signal you get freeze ups and low signal NO picture.

What DOES!!!! matter is what happens to the signal after it gets to the set. A TV set needs a digital High Definition Tuner, and sufficient signal from the source. If the TV sets tuner is NOT high definition you will not get a HD picture. A converter box is NOT an HD tuner.

If the digital HD tuner receives a signal from (any source) on any kind of wire, and that signal is in high definition and the TV sets tuner is capable of receiving it and the TV set is capable of displaying it you will get a high Definition picture.

The digital over the air broadcast sent out by a TV station normally contains at least one high definition signal and two to four regular definition signals. Your TV's digital tuner will sort it all out automatically. Just give the set a good signal from an antenna.

The reason an RCA or Coax VIDEO WIRE is considered- non high definition- is that it by passes the tuner and goes into the TV's video circuit. So the signal must be in high definition going into the video circuit. Composite video or video coming form the coax output of a converter box is not high definition.

The coax wire is fully capable of carrying all the high definition signals available at the same time. A cable system uses coax to carry all their channels high definition, digital and analog. So to will the antenna's coax wire.

(This answer assumes you are located in the US) >Can my antenna receive HD signals? Yes your antenna can receive HD signals. And plain old (RG-6, RG-59) coax cable works fine to get the HD signals to your HDTV. >When I press the guide button it says some channels are 1080i HD and others are 720p HD. The signal resolution (1080i - 720p - 480i) is set at the TV stations. However, your HDTV always displays a 720p picture. Your HDTV converts any signals that are 1080i or 480i to 720p for display. Some people will tell you that a coax cable can't send a HD signal. This is not true for antenna and direct cable connections. However you can't use ordinary (RG-6, RG-59) coax to send a HD quality signal from a video source to your HDTV. HD video sources include HD cable boxes, Blu-Ray players, and HD video games. This is due to cost and legal limitations in manufacturing the equipment and is not a limitation of the coax cable itself.

If his HD tv has an internal tuner, the antenna will allow him to run a channel scan when he plugs it in and if the broadcast station towers are close enuf to his house, he will be able to pick up some or all of the network stations, in HD, and other stations in SD.

The determining factor is distance from the towers and where the antenna is placed. Obviously, outdoor antennas will pick things up better than rabbit ears inside.

But it will work with the coax as the tv will provide the tuner.

The digital converters are not necessary for digital tvs with internal tuners.

A single coax from an antenna can carry an HD broadcast signal - no problem.

A single RCA video cable cannot carry a HD video signal.

I think you are getting the two mixed up. All this HD stuff does get confusing

Yea I bought one that said the same thing, and what i found out is that they were meant to work with the converter boxes and the TVs that come with a built-in Tuner (built in converter box) and It does receive HD channels that transmit 1080i over the air even though they have a coaxial output.