Radar-transparent Makrofol® UV films for radomes and sensor covers

Automotive radar housing: the unsung role of the radome

Radar technology is only as reliable as the cover in front of it. In modern vehicles, that cover is the radome: a protective automotive radar housing, often built into the emblem or front grille. This critical component has to handle two jobs at once: let radar signals pass through with minimal interference across the 76-81 GHz range, and stand up to UV exposure, temperature extremes, stone chipping and chemical contact. 

Advanced driver-assisted systems (ADAS) and radar-based safety systems are now standard across a growing number of vehicles. Functions like adaptive cruise control, parking sensors and blind spot detection are paving the way for autonomous driving. This means that the humble radome has a major safety role: to ensure high-frequency radar transparency coupled with high impact resistance.

Any degradation of the radome cover-yellowing, hazing or micro-cracking caused by UV exposure - alters its dielectric properties and impairs the radio frequency (RF) signals passing through it. Even a modest increase in signal loss at the 76–81 GHz frequencies used by modern automotive radar is enough to reduce effective detection range or trigger real-time false readings. For safety-critical ADAS functions, this is not acceptable. The radome cover material must remain RF-transparent and dimensionally stable over the entire service life of the vehicle. However, this is more than conventional polycarbonate films can reliably deliver.

The technical challenge inside automotive radar housing

Exterior radomes face relentless conditions. Blazing sun, bitter cold, grit, stones and chemicals can all impact the housings that automotive and exterior radar systems depend on. Standard polycarbonates can yellow, haze, crack or grow brittle over time. For ADAS sensor covers, this leaves a narrow engineering path for the radome: the material solution must protect the radar technology and allow free-flowing high-resolution transmission while still looking good.

Standard films may be enough for less exposed interior uses. Exterior radomes demand radar reliability in all conditions. Our UV-resistant radome films are built for exactly these requirements.

Makrofol® UV radome protection films: engineered for automotive exteriors

Our Makrofol® UV polycarbonate protection films are specifically developed for demanding automotive exterior and outdoor applications, including radomes. In these applications, our films are part of a coated radome stack, adding valuable additional UV protection, material performance, processing flexibility and an extra safety margin in cases such as stone chipping.

Here, Makrofol® UV244 is the transparent workhorse. Based on Makrolon® polycarbonate, it combines inherent mechanical, thermal and optical properties with formability, printability and higher UV resilience. This makes it well suited for transparent, formable components with printing and integrated heating layers, such as car emblem radar covers processed using film insert molding (FIM). Makrofol® UV328, available in white or grey, takes on tougher exterior weathering demands: this extra weathering-resistant polycarbonate film offers the highest UV resistance in the Makrofol® film portfolio, making it the preferred choice where color is secondary, such as exposed autonomous driving sensor housings.

For automotive OEM customers in the US and globally, Automotive Manufacturers Equipment Compliance Agency (AMECA)-certified plastics can also be an important requirement for front-end exterior materials. Standard polycarbonate décor films reached Yellowness Index (YI) values above 15 in accelerated outdoor weathering testing lasting over 5,000 hours under the Florida conditions of ISO 4892-2A. A Yellowness Index above 15 is not merely cosmetic: the associated shift in optical density and dielectric properties impairs RF signal transmission through the radome cover, directly undermining radar reliability and affecting the vehicle’s front-end appearance over time. That is precisely where Makrofol® UV films come in — engineered to help close this performance gap while keeping the radome clear for its radar-critical role.

Makrofol® UV: high-quality RF-transparent material for varied exterior applications

Radomes may look simple from the outside, but the design task is anything but. 

They are no longer just protective covers. In modern front-end designs, they can be integrated into car emblems, exposed to years of sun and weather, shaped into complex molded components or combined with targeted heating functions. 

In cold-climate markets, ice or snow on the radome surface can impair the radar signal - making integrated heating not just a comfort feature but a radar reliability requirement.
 
Makrofol® UV films support FIM heating for sample parts and finished components - embedding conductive heating circuits directly into the radome stack to keep the radar area clear and the signal unimpeded even in winter conditions.

And the potential doesn't end at the vehicle: see the FAQ below for where else radar-transparent protective covers come into play.

Wherever the application leads, our polycarbonate UV films offer a tough, flexible solution with high-frequency radar transparency. No single film fits every case — the right grade depends on your specific application profile, and our Specialty Films team can help assess and advise. Request a sample of or speak to us today.

FAQ: Radar-transparent protective covers in practice

Wherever a radar or sensor system operates outdoors, its cover faces a similar balancing act, letting the signal pass while withstanding weather. That makes Makrofol® UV films a potential choice for radar-transparent protective covers well beyond the vehicle front end — for example in photovoltaic (PV) installations, offshore radomes, drones, and other exterior sensor housings exposed to sun, temperature swings and impact. The same combination of high-frequency radar transparency, formability and UV resistance that serves automotive radomes can be evaluated for these applications on a project-by-project basis.

• Signal performance: dielectric behavior and transparency at the system's operating frequency
• Environmental exposure: expected UV load, temperature range, chemical and impact conditions over the service life
• Processing and design: required geometry, printability and suitability for processes such as film insert molding (FIM)
• Functional integration: whether features such as integrated heating layers are needed

For exterior radar applications, it's this combination — not any single property — that determines long-term performance. Whether the cover shields a vehicle radar, a drone or an outdoor sensor installation, the selection logic remains the same: define the requirements first, then match the film to them.