Sensor pod

From Memory Alpha, the free Star Trek reference.

A sensor pod is a module that can be connected to the dorsal surface of a starship to extend a starship's sensor capability.

Several Federation starship designs employed this feature, namely the Danube-class runabout, which was fitted with sensor pods for specific types of missions. (DS9: "Past Prologue")

Other Federation starships to include sensor pods of various designs including Miranda-class starships, with two large sensor pods located port and starboard; and Soyuz-class starships, with large sensor pods that resemble large outboard weapons. (TNG: "Cause and Effect"; DS9: "Emissary")

It has been theorized that the circular pod used on the Nebula-class starship USS Phoenix may have also been a type of sensor pod.

Danube-class with a sensor pod.

Miranda-class with sensor pods.

Soyuz-class with sensor pods.