AN/SPS-40
| AN/SPS-40 on USS Trenton | |
| Country of origin | United States | 
|---|---|
| Manufacturer | Lockheed Electronics Company | 
| Introduced | 1961 | 
| Type | 2D Air-search | 
| Frequency | 400 - 450 MHz, UHF band | 
| RPM | 
 | 
| Range | 250 nmi | 
| Diameter | 140" x 214" | 
| Azimuth | 0-360° | 
| Elevation | Vertical beam width 19° | 
| Precision | Horiz. beam width 10.5° | 
| Power | 200 kW - 300 kW | 
The AN/SPS-40 is a United States Navy two-dimensional, long range air search radar that is capable of providing contact bearing and range. It was replaced by the AN/SPS-49 on newer ships and on ships that received the New Threat Upgrade. The SPS-40, being a vacuum tube design, was notoriously sensitive to the vibration from shipboard gunfire. A later redesign into a largely solid-state system not only improved its performance (cutting the number of cabinets by more than half) also featured one of the best MTI (Moving Target Indicator) units in the fleet - a rarity in the early 1970s.
In accordance with the Joint Electronics Type Designation System (JETDS), the "AN/SPS-40" designation represents the 40th design of an Army-Navy electronic device for surface ship search radar system. The JETDS system also now is used to name all Department of Defense electronic systems.