HRM HD Radio Mapping

At a crime scene invisible RF sources are elements of evidence for alldoor location finding for the geotimeline of a mobile. More and more we recognize that Bluetooth is enabled in addition with cellular. But Bluetooth LE Low Energy only reaches <1m/39.39". If no preinstalled observation beacons were installed no evidence from. In iOS 11.0.2 if you disconnect on the control center the WiFi, WiFi just disconnects from the actual WiFi but stays turned on. So WiFi is my friend for indoor location finding. We have the vision to engineer a backtrack bag full of tech for a HRM. Mobile power based is a high precision geospatial GPS/GNSS/Beidu/GLONASS inearthal receiver with logger. But mom has kids -)

See what I mean
https://static1.squarespace.com/static/5727a25a1bbee088172a1d40/t/59c298e2f6576e9cca935cb9/1505925354283/tuesday.png?format=1000w

We want to build HRM cubes not bigger than 15x15x15cm as RF collector satellites - telling mom what they see (measure). Actually we are little stuck in the antenna design for such a small unit.
Who knows very tiny but highly accurate 2,4GHz rotating antenna on a gimbal mounted? For the embedded computing we focus on Liger
https://www.versalogic.com/Products/PDF/DS-Liger%20EPM-43.pdf

But Do you have a better embedded computer in use? We feel unsecure, can you give advice?

If your unit is running a similar HRM unit, pls PM me.

P.S. we know 5GHz is in the air too -)