Part 107 UAS pilot reported an airborne conflict with a low-flying military aircraft while conducting a test flight in controlled airspace. The UAS pilot took evasive action to avoid a possible collision.

Narrative

Myself; a VO; and a Driver of a chase vehicle were conducting C-UAS Radar testing for our employer in the city of Location A to refine our detection of UAS. We were operating under part 107; as a commercial operation. We had issued and received our LAANC authorization through Aloft.ai; as we do for all of our testing. Our flight path was north and south along Location B in Location A. Our Authorization was up to 400'AGL from the southern end of our approved corridor to the North-Western edge of the Class D. I was in the Backseat of the vehicle as the R-PIC; my visual observer was in the front passenger seat; and our driver was driving the vehicle 100-150m behind the drone during our north and south runs. We were starting our run to the north from a location starting at Location C and Headed north. When the drone was at Location D Indicated by flight logs when evasive descent occurred; I heard the indistinguishable roar of an F-16 as it flew fast and very low over our chase vehicle; flying from the East; and turning towards the north as if they were doing their break to land maneuver; and were in the crosswind to downwind leg of the pattern. I looked out the left side window and would estimate that it was at roughly 400-600'AGL; I immediately descended the drone to around 210' AGL as an evasive maneuver to stay clear of the F16. Their altitude 3nm away from the end of RWXX at ZZZ seemed way too low for being that far out in the pattern regardless of the maneuvering they were doing. I don't think collision was imminent however; if the incident had happened about 30 seconds earlier; I believe the drone would have posed a threat to the flight safety of the F16. As a manned Commercial pilot; I would have been calling the tower about another manned aircraft being as close to an aircraft I was operating if an F-16 had gotten that close to me under manned operations. The DJI Air 3s that we are operating with has 'Airsense' which is ADSB-In and will alert the operator via the controller/GS when an aircraft is present in the area and may pose a potential collision hazard. Since the F-16's don't broadcast ADSB; I was unaware of their operations that day since I had not seen any up until that point. Normally we operate with ADSB-Exchange on a tablet to monitor other air traffic within our operating area and to try and expect oncoming traffic as it relates to ZZZ so we can mitigate potential incidents such as this. However; again because F-16's do not broadcast ADSB-Out; we did not know they were operating until it was directly overhead our chase vehicle. Even though the F-16 had flown behind and around to the front of the drone; I still descended to 'give room' to the F-16. We have access to Handheld Radios that monitor the ZZZ ATC traffic; but with the F-16's primarily communicating with UHF to the ATC tower there; I doubt that any transmission from them would have came through clear enough to understand that one was doing a break to land. As remedial action from this incident; our VO's have been re-trained on scanning the airspace around us when taking short breaks from maintaining visual contact with the drone; and have been instructed on the importance of air to air conflict resolutions techniques such as descending; stopping; ascending; etc. I take full responsibility for the safety of the flight an am a huge advocate for all of the flights conducted for myself and the company I work for. I have successfully taught a class of 10 individuals and they have all passed their Remote Pilot written tests and have received their Part 107 certificates in an effort to get more people qualified for the use of drones in our line of work. Safety is always number one and I hope some sort of resolution can come from this that may mitigate any further potential issues with air to air near misses with fast movers such as the F-16's. I am open to further discussion with the FAA; Air National Guard base; and ZZZ to work towards a collaborative solution to mitigate these happenings as the frequency of our testing will increase with time and the possibility of this occurring again may still be present.