The Dream Aerial doesn’t become useless after first use and can be used to hunt for more organic frigates.
You don’t need an anomaly detector to find more after the first frigate. Just keep the Dream Aerial in your inventory and keep pulsing.
To deactivate the frigate searching, either dismantle the Dream Aerial or move it into a storage container or your personal refiner.
None of the frigates found will be free.
They will have the same class and stats as if they were found by an Anomaly Detector.