Pilot reported an erroneous target on ads-B display.

Narrative:

I was on a VFR (visual flight rules) cross country flight at 4;500 feet MSL. Weather was clear with no ceiling and at least 25 mile visibility. I was cleared into ZZZ bravo. While approaching ZZZ my adsb (automatic dependent surveillance broadcast) showed a target to my south at the same altitude and 4 mile away. I could not see it but kept an eye on my screen. It started to converge and eventually I got an aural warning from my adsb. During that time I lifted the wing of my aircraft to be sure I hadn't missed visual sight of the traffic. I still couldn't see it yet it was now very close so I called ATC (air traffic control) and asked. Their reply was that the only traffic they saw for me was about seven miles to the north or northwest. Very shortly after that the image on my screen converged completely and the disappeared. I continued the flight normally and while listening to ATC another aircraft called in with the same situation. The controller mentioned to him that another aircraft had this as well. I chimed in and told the controller that it was me and he asked a few brief questions because he was concerned. No negative outcome just a disturbing puzzlement. My conclusion was a phantom signal from my own airplane; a bounced signal; or perhaps an unauthorized drone. Very peculiar so I decided to report it.

Original NASA ASRS Text

Title: Pilot reported an erroneous target on ADS-B display.

Narrative: I was on a VFR (Visual Flight Rules) cross country flight at 4;500 feet MSL. Weather was clear with no ceiling and at least 25 mile visibility. I was cleared into ZZZ Bravo. While approaching ZZZ my ADSB (Automatic Dependent Surveillance Broadcast) showed a target to my south at the same altitude and 4 mile away. I could not see it but kept an eye on my screen. It started to converge and eventually I got an aural warning from my ADSB. During that time I lifted the wing of my aircraft to be sure I hadn't missed visual sight of the traffic. I still couldn't see it yet it was now very close so I called ATC (Air Traffic Control) and asked. Their reply was that the only traffic they saw for me was about seven miles to the north or northwest. Very shortly after that the image on my screen converged completely and the disappeared. I continued the flight normally and while listening to ATC another aircraft called in with the same situation. The Controller mentioned to him that another aircraft had this as well. I chimed in and told the Controller that it was me and he asked a few brief questions because he was concerned. No negative outcome just a disturbing puzzlement. My conclusion was a phantom signal from my own airplane; a bounced signal; or perhaps an unauthorized drone. Very peculiar so I decided to report it.

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.

Attributes
ACN	1742588
Time
Date	202005
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	None
Component
Aircraft Component	Navigational Equipment and Processing
Person 1
Function	Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 12 Flight Crew Total 1200 Flight Crew Type 950
Events
Anomaly	Aircraft Equipment Problem Less Severe Conflict Airborne Conflict Deviation - Procedural Published Material / Policy