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New for July 2026. Radomes are what protect antenna elements from the elements (weather). Depending on application, a wide variety of materials are used. Radome designs take into account electrical (dielectric constant and dissipation factor) and mechanical (weight, strength, thermal resistance, thermal expansion, etc...) material properties.
Radome materials with appreciable dielectric constants typically must be are sized at multples of a 1/2 of a wavelength (in the material, not free space) to reduce their effect on antenna performance. Radomes affect beam forming (particularly with scanning antennas), and generate VSWRs back into the antenna that need to be minimized to prevent transmitter damage. Very low dielectric materials have a distinct advantage in radomes: their thickness may be based on mechanical properties only, as they have a lesser affect on the antenna beam.
Cell tower radomes
For cell phone towers (base stations) and such, a material that protects from rain and UV exposure (sunshine) is needed. Base station radomes do not encounter heavy loads or temperatures associated with airborne applications. Cheap is the key word... fiberglass, plastic, or teflon materials have been used.
4G systems and older have fixed beams (no scanning), while 5G antennas are electronically scanned, Therefore, 5G radome designs are more design-intensive.
PhaseBlue has developed a low dielectric material using foamed polyimide which is suitable for 5G cell. DK is 1.3 to 1.5 and dissipation factor <0.001. Because of the low DK, the thickness of a PhaseBlue radome is flexible. Combining low dielectric, low loss materials with in a very thin radome (less than a half wavelength) seems like it offers a nice performance advantage worth checking out.
Missile radomes
For missiles, radomes can heat up substantially due to friction with air, and can be ablated by flying through weather. On the other hand, the system only has to last a minute or two. In radomes, ceramics or composites may be used. These materials tend to have a dielectric constant in a range of 3 to 6. In order to make the material invisible to a radar, a half wavelength thickness is sometimes used. If you can figure out the dielectric constant, and you know the thickness of the dome, you can arrive at the missile radar frequency. For this reason, missile radomes and drawings may contain classified information.
Here's an article on missile radome materials. Here's a white paper on radomes that also includes materials.
Pryoceram
One material used in missile radomes is Corning's Pyroceram, it was invented in by Dr. S.D. Stookey at Corning in 1952. Dr. Stookey appears in our Microwaves Hall of Fame, check it out! Pyroceram, a portmanteau of pyro (ancient Greek for fire) and ceramic, was a trademark for a family of materials, but the trademark is currenty only assigned to windows on wood and fuel burning stoves and furnaces. In the past, Pyroceram was also used to produce cookware that could withstand moving from the freezer to a hot stove, you can find vintage examples on Ebay. Pyroceram came in several different flavors, Corning 9606 is currently used in missile radomes. Its properties include:
- Maximum temperature: 1350C
- Coefficient of thermal expansion 0.57E-6
- Dielectric constant: 5.6 at room temperature (increases with temperature)
- Dissipation factor: 0.0002 at room temperature (increases with temperature)
Slip-cast fused silica
Another missile radome material is slip cast fused silica, which is a cousin to the countertop material that California is trying to ban (man-made quartz). Machining or sanding anything with silica in it can cause lung diseases.
The "slip" in this process is material made of ground up silica in a specific particle size distribution. It is placed into a plaster mold, then fired. Shrinkage is remarkably low at 1 to 2 percent. Its properties include:
- Coefficient of thermal expansion: 0.54E-6
- Dielectic constant 3.2 at room temperature (increases with temperature)
- Loss tangent 0.0002 at room temperature (increases with temperature)
Rayceram 8
Up until the 1990s, Raytheon made their own ceramic missile radome material at their now-closed Lowell, Massachusetts facility. Rayceram 8 is mentioned in this 1992 article. Once used on AMRAAM missile, it was probably a victim of the 1997 merger with Hughes. Mergers are why we can't have nice things...
Speaking of that Lowell facility, in 1996 it was part of a murder case.
Future hypersonic missiles will need new radome materials, as heating is going to be much higher.
You can download a free 1964 report on SCFS on DTIC.
Commerical aircraft radomes
Viasat makes phased arrays for on-board internet connectivity. You can see these radomes on top of the aircraft. The material has to withstand 600 mph winds, rain, hail, birds.... Thankfully, the dome is not part of the pressure hull so it doesn't have to withstand pressurization changes, but it surely has the gets the crap knocked out of it.
General Dynamics developed a triband dome for one version of Viasat's system (Ku, K and Ka bands) using a quartz fiber/epoxy material.
Got any info on radomes you'd like to share? Send it our way!