Why We Use ASA for Outdoor Structures

At RF.Guru, our design philosophy is clear: build it once, build it to last. That means selecting materials that withstand the elements, preserve mechanical and electrical integrity, and simplify manufacturing. One of our core engineering choices is ASA (Acrylonitrile Styrene Acrylate) — a high-performance thermoplastic tailored for demanding outdoor RF use.

What We Use ASA For

We currently deploy ASA in several outdoor-critical components:

• Antenna Mounting Brackets – The U-bolt clamp bracket that attaches our UNUNs securely to vertical masts
• Mini Coil Supports – Used in our multi-band fan-style verticals to insert inductive loading at 60–70% of element length. These ASA coil supports are wound directly onto the wire, avoiding extra hardware
• Spacing Plates – Maintain stable separation of radiating elements in fan-style verticals
• Non-Resonant Coaxial Trap Housings – Where mechanical durability and RF neutrality are vital

Why ASA?

ASA offers a set of mechanical and electrical advantages that make it ideal for outdoor RF systems:

• UV Resistance – ASA resists solar degradation better than ABS or PLA, retaining strength and color over time
• Dimensional Stability – Maintains mechanical integrity across a wide temperature range
• Weather & Moisture Resistance – Non-hygroscopic and stable in freeze-thaw environments
• High Dielectric Strength – Functions as a robust insulator even in high-voltage or high-field RF environments
• RF Transparency – Electrically stable across HF to UHF, making it suitable for RF-adjacent support structures
• Heat Tolerance – Withstands soldering proximity, thermal cycling, and sun exposure without melting or deformation
• Ease of Integration – ASA prints cleanly to spec and bonds well to itself and other plastics when needed

The RF Benefit

In RF design, mechanical materials are never just structural — they’re part of the circuit environment. When components shift, expand, or couple unintentionally, performance drops. ASA’s stability ensures our products hold their shape, maintain spacing, and preserve electrical behavior across the seasons and across the bands.

Material Comparison Table

Property	ASA	ABS	PETG	PLA
UV Resistance	Excellent	Poor	Moderate	Poor
Water Absorption	Very Low	Moderate	Moderate	High
Dielectric Strength	High	Moderate	Moderate	Low
RF Transparency	Excellent	Good	Moderate	Poor
Heat Resistance	High	Moderate	Good	Low
Mechanical Rigidity	High	Moderate	High	Brittle
Printability (FDM)	Good	Good	Good	Excellent
Outdoor Suitability	Excellent	Poor	Moderate	Poor

 

Final Thought

ASA might not be flashy — but it’s one of the invisible advantages behind the reliability of our systems. From RF transparency to mechanical toughness, it’s a material choice that reflects our commitment to long-term, field-tested performance. That’s part of what Build to Last really means.

 

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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.