I live in Salinas, Ca. I have Directv with an HD DVR. Directv does not offer the local channels (Fox, NBC, CBS, ABC) in HD. The local cable company, Comcast, and DishNetwork both do have the local channels in HD. I contacted Directv and looks like they will not have the local channels in HD for a long time to come. Seems it will cost them a lot of money to do so. So with two HD televisions, we watch many programs in HD but not the local channels.
So I either switch to DishNetwork or find some device that will allow us to be able to watch all of the local channels in HD (when you watch an NBA game in HD on TNT and then watch a game on sunday on NBC in standard format, it is a huge difference https://tweakbox.mobi/ https://tutuappx.com/).
I was reading about the Terk Technology HDTVi UHF/VHF HDTV Indoor Antenna as as a possible solution. Does anyone have any suggestions so we can get HD on our local channels or is it not possible?

Your television has a HD tuner built into it, all you need is an antenna. As far as which antenna, that all depends on where the broadcast antennas are in relationship to you, distance, obstacles like mountains, are they all in the same direction. There used to be a website that would locate where the antennas where in relationship to you and would recommend what kind of antenna to get.

All that being said, all of the indoor antennas are pretty hit-or-miss. If there is too much interference or distance between it and the broadcast antenna, you won't get any kind of reception. For example, I did one here in Houston for the Superbowl at the beginning of the year, TV was on a cart and wheeled out in the garage, I was able to pick up about 14 off-air channels, but only 2 were major networks, the rest were small time, spanish, or shop at home stations. That was just using a basic amplified Terk indoor antenna.

I knew of two websites that would tell you what the signal strengths were and which direction they were coming to you at. (Poor English, sorry.)

I just looked and only found one: tvfool.com. But it'll tell you what's going on.

Check it out and drop me an email if it's not clear enough. One thing that's strange till you get used to it is the state of the call signs and frequencies. Again, drop a line if it's not clear.