PA-28 pilot reported an near midair collision in the pattern at rhv.

Attributes
ACN	1266798
Time
Date	201505
Local Time Of Day	1201-1800
Place
Locale Reference	RHV.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	None
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine Flight Crew Flight Engineer
Experience	Flight Crew Last 90 Days 50 Flight Crew Total 16000 Flight Crew Type 300
Events
Anomaly	ATC Issue All Types Conflict NMAC
Miss Distance	Horizontal 500 Vertical 100

Narrative:

On entering downwind leg ATC advised of departure traffic that would pass in front of us. We reported to ATC that traffic was not in sight and [asked] if they would like us to modify our downwind to mitigate traffic issue. ATC told us to fly downwind at our discretion and to maintain 1;500 feet MSL until advised. I was able to see traffic who was slightly above us but appeared contact was imminent. I made an evasive dive and turn to avoid collision. We were on flight following with norcal and assigned transponder code prior to entry into class D airspace. Tower was notified of evasive action.

Original NASA ASRS Text

Title: PA-28 pilot reported an NMAC in the pattern at RHV.

Narrative: On entering downwind leg ATC advised of departure traffic that would pass in front of us. We reported to ATC that traffic was not in sight and [asked] if they would like us to modify our downwind to mitigate traffic issue. ATC told us to fly downwind at our discretion and to maintain 1;500 feet MSL until advised. I was able to see traffic who was slightly above us but appeared contact was imminent. I made an evasive dive and turn to avoid collision. We were on flight following with NORCAL and assigned transponder code prior to entry into Class D airspace. Tower was notified of evasive action.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.