Dielectric Applications from Low-Density Rigid Foam

Low-Density Rigid Foam

Image Credit: General Plastics

Recently, General Plastics introduced its sophisticated dielectric foam material for use in antennas, radomes and other radio frequency (RF) communication systems. The LAST-A-FOAM® RF-2200 Dielectric Series is a thermoset plastic that focuses on several needs for an RF-transparent protective layer with extended thermal processing capabilities. These include low-loss properties and a low dielectric constant supported by products in a low density range.

Fulfilling Designer Needs

The RF-2200 materials offer several benefits, ranging from water absorption to high processing temperatures to their resistance. This material was formulated with a glass transition temperature (Tg) that sustains usage temperatures up to 350 °F, permitting thermal curing of high-temperature composite prepregs and supporting manufacturing processes that are compatible with BMI resins. Considering these enhanced mechanical/thermal properties, designers can assemble panels with greater dimensional stability, which is essential for consistent, long-lasting performance in the field, even in adverse environments.

The dielectric performance of LAST-A-FOAM® materials is unaffected even when exposed to moisture. This is a remarkable characteristic of LAST-A-FOAM® materials.

Our foam’s chemistry doesn’t break down.” “Rain or moisture on the foam’s surface isn’t absorbed into the foam as can happen with other dielectric materials, dramatically changing their dielectric performance.

Joe Nichols, Technical Sales Manager

Aside from the material’s ability to resist water uptake, RF-2200 foams are furnished in custom sizes. Furthermore, their cell shape and density are homogeneous within each block and from sheet to sheet. Signal transmission and reception are improved by their homogenous cell structure.

Far-Ranging Applications and Environments

Along with the higher-density dielectric materials (FR-3700 and FR-7100), the RF-2200 series neither changes nor inhibits signal transmission. It is predominantly used as composite material in construction of antennas, radomes, and for electronics isolation. These structures can differ in size from the small domes seen on yachts to exorbitantly large coverings spanning dishes that bear resemblance to roofed stadiums.

Since the low-density RF-2200 tolerates higher processing temperatures, it supports thermal curing of prepregs used to create stronger, more reliable panels. The material is also lightweight, and simple to handle, machine and coat, which makes it perfect for installing and assembling panels in a space-frame radome.

Reliable performance in the field is guaranteed when it comes to the material’s physical properties. The dielectric foam from General Plastics has been used as components of the radome installation on naval attack vessels. Reliable performance is crucial because the radomes guard the radar or communications for military access. Such defense customers rely on the dimensional stability, strength, endurance, and water resistance of the dielectric materials.

Other applications include radomes that shield Doppler radar, which is used to measure the speed, direction, or velocity of precipitation, and hence, wind. It helps to figure out if it is safe for airplanes to land at airports.

Doppler radar helps air traffic controllers assess levels of wind shear. This application is for land based radar and radomes. The simple radome structures on these antennas hold up to hail and variable high-to-low temperature exposures.

Joe Nichols

RF Foams as Integral Antenna Components

With the growing omnipresence of antenna systems for data delivery and communications, General Plastics’ RF-2200 foams are also proving to be an ideal material for active, internal components of antenna systems.

“We’re seeing our dielectric foams used as stand-offs or other spacer materials in antenna designs,” mentioned Nichols. “Oftentimes the distances between active components are critical to the performance of those antennas. Our materials are potentially transparent to the radio waves, but keep the other components at their proper distance and location so they perform correctly.”

These products are lightweight but also stable and capable of accommodating the design loads that will be applied to them. Thus, even in situations of hail strikes, high wind, or other potential environmental dangers, the antenna perseveres to function over its design life.

As the world moves faster, the yearning for continuous data access is driving development of novel antenna systems to extend communications capabilities and Internet access on everything from public transportation to personal vehicles. General Plastics is involved in these applications, which require lightweight RF foam materials to aid very large antennas transporting large volumes of data.

Electronics Isolation Applications

General Plastics’ new polyurethane RF foams are also used for the packaging and testing of electronics. Nichols says that high-end electronics manufacturers ought to test their products at distinct stages of manufacturing.

They will request the dielectric properties of our foams because they need materials that will not reflect or absorb radio waves – that’s a critical part of their test apparatus.” “Our RF-2200 materials allow them to support the equipment that’s being tested without interacting with the radio waves themselves.

Joe Nichols

Furthermore, these materials can be used as electronic packaging insulation and electrical isolators, used accordingly to manage or alter the electrical surroundings of components.

LAST-A-FOAM® RF-2200 is available in densities of 3, 4, and 6 pounds per cubic foot. General Plastics also offers custom densities to fulfill project requirements for a specific dielectric constant and/or loss tangent. In addition to providing material and pertinent technical finesse, General Plastics can also support customers’ needs for ready-for-assembly, machined-to-spec parts.

Nichols said, “Our team of expert engineers and chemists is always eager to determine the properties a customer needs and offer them the most value-appropriate product.”

This information has been sourced, reviewed and adapted from materials provided by General Plastics Manufacturing.

For more information on this source, please visit General Plastics Manufacturing.

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