There are several mobile radar sites and various support buildings northwest of the Area 51 North Gate guardhouse, less than a mile inside the perimeter. The sites are installed semi-permanently, almost in line with the north end of the Groom runways. What makes these sites particularly interesting is the fact that they are Russian models. They are used to test the stealth capabilities and other properties of new or modified aircraft coming out of Area 51 against actual enemy hardware. Similar radar sites can be seen in the vicinity of Cedar Gate, further to the north.

Sometimes at night you can see the red and blue radiation warning lights of the radar sites from Rachel. This indicates that they are active, and that a test is about to begin or is already in progress. They usually come on about one or two hours before the actual test flight.

Update 04/02/2019: A new Russian P-37 "Bar Lock" radar site was added in late March of 2019.

Update 10/31/2021: Added a new high-res photo of the P-37 radar.

Update 11/30/2021: A new S-125 "Low Blow" radar site was added at the Back Gate.

Update 11/30/2021: A new tower was added inside the Back Gate with microwave intrusion detection gear.

Update 06/12/2022: The radar sites use the following center frequencies (bandwidth about 400-500kHz): 150.200, 155.650, 165.900, 180.400 MHz

Update 05/2024: All Russian radar sites inside the perimeter by the Back Gate are gone. We suspect that they were moved to more secure locations in the northern Emigrant Valley, the valley north-west of Area 51.

Update 09/12/2024: A new radio tower with a powerful FM radio transmitter was added just inside the Back Gate.

Related links:

• The Area 51 North Gate - The new upgraded Back Gate of Area 51
• The old Area 51 North Gate - The old guard shack, prior to the upgrade in October 2000
• Radar Sites near Cedar Gate - Radar sites near the Cedar Pass gate further north
• Rest-of-World Missile Systems - FAS: Basic characteristics of selected "Rest of World" missile systems.

This new 100' radio tower was constructed about 0.4 miles inside the Area 51 Back Gate in 09/2024. The antennas (shown from two slightly different angles) turn out to be a powerful FM radio transmitter, broadcasting synthetic music of various flavors on 99.9 MHz ("Radio Backgate", 37° 35.451'N 115° 54.296'W). The transmitter is only active during missions. Another transmitter in EC-West near TTR is active Monday morning thru Friday early afternoon on 99.1 MHz (Radio S4", 37° 44.128'N 116° 29.850'W). Both transmitters are likely part of testing jamming hardware for passive radar systems. Passive radars have no transmitter but utilize existing FM radio stations for detection of aircraft by measuring their reflection. On 10/09/2024 we monitored a mission involving the radio sites. One of the Beech Janets, N661BA, operating from TTR, was flying in the area and testing an onboard system referred to as "Pluto". [09/12/2024]

This Russian S-125 "Low Blow" radar site was added to the collection of foreign radar systems near the Back Gate in November of 2021. It sits about 1/3 mile inside the perimeter. It is an I-band acquisition and tracking radar for the SA-3 missile, designed to guide the missile towards low-flying targets through heavy clutter. A pair orthogonally mounted, electromechanically scanning antennas improve low-angle performance by reducing interference from ground clutter. This is a very capable system: A single battery shot down both the F-117 and an F-16 during Allied Force. Click here for a photo of the site being delivered on a flatbed truck on 10/30/2021. [11/30/2021]

This radio tower about 0.8 miles inside the perimeter was likely added in the fall of 2021 in a location that is not easily visible from the Back Gate. It is very similar to a new tower added near the Groom Lake Road gate around the same time. It includes a microwave intrusion detection system and a high speed data relay from Cedar Peak to the Back Gate and to mobile units in the area. [11/30/2021]

Aerial image of the Back Gate area showing the radar sites just inside the fence line in the foreground. The Side Net in the back right, Spoon Rest center and Bar Lock front right. The other three sites are not currently used. Photo by Gabriel Zeifman [05/24/2020]

Aerial view if the P-37 "Bar Lock" (see below) seen from inside the restricted area. This view reveals the support buildings hidden behind the dirt ramp that the site sits on. Photo by Gabriel Zeifman, with friendly permission [05/24/2020]

Another high resolution photo of the P-37 radar site (see below) from a slightly different angle. [10/30/2021]

This radar site was added in late March 2019. It is a Russian P-37 "Bar Lock" air defense search radar. The radar operates in the frequency band 2695-3115 MHz and has a range of 250NM with a resolution of 0.1NM. [05/28/2020]

Russian "SPOON REST A" target acquisition and early warning radar. Its range is 275 km, the max. altitude 32 km. It operates in the VHF Band, we are told possibly around 150 MHz. [12/17/2011]

Russian "PRV-11 SIDE NET" height finding radar, similar to the one near Cedar Gate. It was designed for use with the Russian "S-200 SA-5 GAMMON", which is a medium to high altitude surface-to-air missile system. It is also used with the SA-2/3 SAM. It has a range of 28 km and a max. altitude of 32 km. The radar operates in the E-band. [12/17/2011]

---

Older Radar Units at the Back Gate that have since been removed

A Russian "LONG TRACK" long-range acquisition radar with a detection range of over 300 km and up to 30 km altitude. The Long Track radar operates in the "E-Band" (2.7-2.9 GHz) and integrates with the "Thin Skin" height finding radar below. This was the first system to detect stealth aircraft by changing modes and frequencies. Long-Tracks and Flatface were used during development of Have Blue, the prototype for the F-117 Stealth Fighter. This site was replaced by the "PRV-11 SIDE NET" (see above).

A "THIN SKIN" height finding radar with a range of 240 km, and a max. altitude of 30 km. It can be integrated with the "Long Track" radar above to provide 3-dimensional target information. It also operates in the "E-Band" (2.7-2.9 GHz). This site was removed some time before November 2006. Both are Russian/Warsaw pact systems and can be used in conjunction with the FAN SONG radar for the SA-2 Guideline SAM. They may be used here for Red Flag exercises, or for testing new stealth technology, currently under development at Area 51.

This radar site was added to the cluster around the North Gate in early 2002. The "donut" in the background contains a rotating radar (see below). The array of four vertical antennas in the foreground is for the mobile Russian air-defense command and control center code named "Mercury Grass". It is a phased lock loop (PLL), line-of-sight, multichannel comm gear that dates to the late 1950's. It became standard field gear for Warsaw Pact, N Korea, China, N Vietnam, and was the primary voice comm gear employed at SA-2 SAM sites. This photo was taken on 11/29/2002. The site was partially disassembled in 2009 and is no longer active.

The same site while it was being set up on 3/29/2002. The rotating radar, now covered under the "donut", is still visible.

Closeup of the new site. Notice the large breaker boxes at the control center. Photo taken on 11/29/2002.

Closeup of the "Spoon Rest". Its main axis is in line with the camera, but its elements are actually pointing to the right

Closeup of one of the "Mercury Grass" antennas above; it is marked "AK 003" near the bottom

"Score Board" IFF interrogator, associated with the "Spoon Rest" and located just north of it