The Navy plans to equip its new Flight III Aegis destroyers with its new SPY-6 radar.  The SPY-6 is made up of 37 self-contained Radar Module Assemblies (RMAs).  The SPY-6 is expected be at least 30 times more sensitive than the current Aegis SPY-1D radar (or 2.3 times the detection or tracking range against a given target).

A reader of my March 13 post noted that in the FY 2020 budget the Navy announced plans to upgrade the SPY-1D Aegis radar on its Flight IIA destroyers by replacing the current antennas and transmitters with a 24 RMA antenna, and asked how this upgraded radar would compare to the current SPY-1D radar and the new SPY-6.

Since the SPY-6 and the planned upgrade to the SPY-D will use the same radar technology, they will primarily differ only in their power, antenna area and gain.  Since each of these is proportional to the number of RMAs, the upgraded SPY-1 radar will have (24/37)3 = 0.27 of the sensitivity of the SPY-6.  However, it will have about (0.27)(30) = 8 times the sensitivity of the current SPY-1D (which is a pretty big improvement).

1. #### Nick

/  April 9, 2019

With Flight III SPY-6 you calc’d ~75% larger array panels than a Flight IIA/Tico SPY-1, Navy stated radar sensitivity scales as a cube of the size of the radar aperture and with it’s new gen GaN T/R Ms SPY-6 reported as ~32 more sensitive/powerful than a Flight IIA /Tico SPY-1 phased array radar

SPY-6 has 37 T/R M Radar Modular Assembly panels, RMAs, (2×2=4 sq ft) per panel array = 148sq ft x 4 panel arrays = total 592 sq ft total array for total 148 RMAs

Recent mention that Navy will upgrade Burkes Flight IIAs with a cut down SPY-6 592sq ft (7×4)= ~336 sq ft total array, 84 RMAs – 4 panel 21RMAs, if Flight IIA can take the increased weight of the top heavy RMAs and has necessary electric power and cooling capacity, cube [(21/37)3=0.18×32=5.76]. Result ~5.8x more sensitive/powerful than the old SPY-1.

New FFG(X) will use EASR 3 panel arrays = 108 sq ft (27 RMAs – 3x panel 9 RMAs) cube [(9/32) 3=0.02] Result only ~0.2 sensitive of a SPY-1, whereas Raytheon claim EASR 3 panel array sensitivity/power equivalent to SPY-1, calc only gives 0.2?, your thoughts?

2. #### Nick

/  April 9, 2019

Apologies need to modify my post, forgot the last calc :(, .02 x 32 = 0.6, so presume near enough to Raytheon claim EASR equivalent to SPY-1.

3. #### mostlymissiledefense

/  April 9, 2019

This seems right to me, although the source I have seen says the Flight IIAs will have 24 RMAs per radar face and in last calculation, shouldn’t it be the cube of 9/37?

4. #### Nick

/  April 10, 2019

Thanks for correction, (9/37)3 = .014x 32 = 0.46. To meet Raytheon claim that the EASR equivalent to SPY-1 you would need a sensitivity of 70, which is what you quote Scott Spence, the Senior Director of Raytheon’ Naval Radar Systems said “It’s 70 times more sensitive than the current radar.”

If the cut down version of SPY-6 for Flight IIAs we use your figure of 24 RMAs per array and Scott Spence sensitivity figure that would give (24/37)3 = 0.272 x 70 = 19 x sensitivity of a SPY-1, though do wonder as said before if Flight IIA can take the increased top weight and has the electric generating/cooling capacity for that number of RMAs, if update is funded we will see the numbers. Lockheed Martin did make an offer to Navy to update the SPY-1 radars pier-side with their dual polarization T/RMs used in the new LRDR, GaN silicon by Wolfspeed, but Navy chose to go with cut down version of the SPY-6.

The Japanese selected the LM LRDR in preference to the Raytheon SPY-6 for their Aegis Ashore, saying the LRDR offered a higher performance, August 2018, so must be looking at a sensitivity of 70+, 80?

From

PS Appreciate your website, find it great as it allows me to undertand radar and BMD.