ZMA Controllers voiced concern regarding two RADAR systems that fail to provide needed RADAR data to controllers.

Narrative

[There is a] recurring safety problem for Miami Center controllers; especially in the Bimini/Nassau area; [in which targets are not displayed] in the HOST system. However; when you switch to EBUS; the target is displayed perfectly. In this situation an A320 was making his descent into FLL; he advised that he is responding to a TCAS RA. The R42 Controller had no display of any target; however; when switched to EBUS as the Controller had awareness of this HOST display problem; the target was observed perfectly; but now being the A320 aircraft. Pilot called in later and advised it was very; very close! This [is] a known; very serious safety issue that has been previously reported through various venues. It is a very serious problem in a highly congested air traffic area that could be rectified with the installment of Freeport RADAR and the upgrade of Nassau RADAR; as it is very old system with questionable maintenance problems. Recommendation: installment of Freeport RADAR; upgrade of Nassau RADAR; and adaptation upgrade so that HOST can display the same targets as EBUS with the same back-ups and redundancy. In other words; the RADAR data is available; but HOST is not displaying it as efficiently as EBUS.