GA pilot reported an NMAC while on downwind to LVJ non-towered airport. The conflicting aircraft reportedly appeared so quickly within 200 feet in the opposite direction that the reporter had no time to take evasive action.

Narrative

I was maneuvering to enter the left downwind leg for Runway 32 at LVJ. I was coming from the northeast and heard there were multiple aircraft in the pattern and did not want to overfly the field since it sits below the 2;000 ft. shelf for HOU bravo airspace. I went several miles south of the airport then came back toward the airport from the west to enter left downwind on 45 degree angle. Made several calls on CTAF stating position and intentions and began coordinating with two airplanes and one helicopter already in the pattern. I entered the downwind leg at 1;000 AGL announcing that I had the traffic on crosswind and traffic on final in sight. A few seconds later I saw an aircraft at my same altitude at about 9-10 o'clock position within a few hundred feet (perhaps closer) moving in the opposite direction. The aircraft appeared so quickly and from a position I wasn't expecting that I didn't have time for any evasive maneuvers. I continued the traffic pattern and landed safely on Runway 32. The aircraft that nearly hit me appears to have been on a direct routing to grass airstrip 3T2 5 nm southwest of LVJ. This routing looked like it was taking him directly over LVJ. The CTAF frequencies for LVJ and 3T2 are different; so it is possible the other pilot was unaware of all the traffic between him and 3T2 if he was only listening to the frequency for 3T2. It is also possible that the other pilot is unfamiliar with the area. Based on the fact that he was in HOU bravo airspace several miles prior to this near miss; I assume that he was talking with ATC. It would be surprising to me if ATC would have this pilot on a track to go through a busy traffic pattern at LVJ; so I assume he was no longer being routed by ATC. Which makes me wonder if the pilot was unfamiliar with the area and didn't realize there was a very busy airport between him and his destination. Another possible factor is that flying into a grass strip that is not very busy like 3T2 can lead to a sense of complacency where recommended radio calls and traffic pattern entry procedures are not always followed. I say this based on this pilot's very low and non-standard entry into the traffic pattern at 3T2. In my opinion; this pilot should have either stayed in the HOU bravo until he was clear of LVJ or should have gone around the area to the south. It is a miracle that he didn't hit anyone as he blasted through a traffic pattern with 4 other aircraft in it.