Low Dielectric Composites for Radomes and Antennas

TenCate Advanced Composites is a key provider of advanced resin systems and composites for the radome industry and antenna industry. The company’s cost-competitive and superior-quality materials are designed for a myriad of high-performance aerospace, electronics, communications and commercial applications. This achievement is a result of its quality products, advanced technology and customer driven approach that promotes teamwork, cooperation and responsiveness.

TenCate Advanced Composites

TenCate Advanced Composites

Radome & Antenna Composites

Today’s advanced radar and satellite communication system manufacturers need TenCate to provide the latest low dielectric prepregs. The company’s adhesives and syntactic foams, liquid resin systems and cyanate ester and epoxy-based prepregs have low moisture absorption, low loss tangent and low dielectric constant properties. The combination of these capabilities and the company’s segregated production facilities completely eliminates conductive graphite from dielectric materials, thus ensuring electrically pure products with better quality.

Radome & Antenna Composites

Radome & Antenna Composites

Meeting the Challenges

TenCate’s materials are specified for production of different shipboard, ground, airborne and space-based products like sonar domes, radomes, reflectors, antennas, radar absorbing and microwave transparent structures. Widely accepted and adopted reinforcements including high density polyethelene, aramid, quartz and fiberglass are completely compatible with the company’s advanced resin systems and can be delivered as prepregs to meet the most challenging mechanical and electrical applications.

Cyanate Ester Quartz Fabric Low Dielectric Epoxy/ Quartz Fabric Low Dielectric Epoxy/ Glass Fabric
Electrical Performance BEST
Dielectric Constant 3.2 to 3.35
Loss Tangent 0.001 to 0.009
BETTER
Dielectric Constant 3.4 to 3.8
Loss Tangent 0.009 to 0.011
GOOD
Dielectric Constant 4.5 and above
Loss Tangent 0.011 and above
Laminate Impact Strength Very Good Very Good Moderate
Temperature Performance High
Tg 275°- 450°+F (135°-204°C)
Moderate - High
Tg 250°- 400°F (121°-204°C)
Moderate - High
Tg 250°- 400°F (121°-204°C)
Laminate Moisture Absorption Lowest
0.1 - 0.6%
Very Low
0.6 - 0.8%
Moderate
1.2 - 1.6%

PREPREG RESIN SYSTEM* Quartz Laminate Neat Resin
Loss Tangent (Df) Dielectric Constant (Dk) Loss Tangent (Df) Dielectric Constant (Dk)
Product Resin Name Type Measured at 10 GHz Cure Temp. °F/°C Tg °F/°C Tg after post cure °F/°C Out of Autoclave Processible
Df Dk Df* Dk
BTCy-2 Cyanate Ester < 0.001 3.28 0.001 2.70 350 °F/177 °C 375 °F/191 °C N/A YES
BTCy-1A Cyanate Ester 0.001 3.33 0.003 2.75 350 °F/177 °C 365 °F/185 °C 405 °F/207 °C NO
EX-1515 Cyanate Ester 0.004 3.20 0.004 2.80 250 °F/121 °C 249 °F/121 °C 345 °F/174 °C YES
RS-3 Cyanate Ester 0.009 3.19 0.009 2.81 350 °F/177 °C 375 °F/191 °C 490 °F/254 °C YES
TC420 Cyanate Ester 0.009 3.39 0.01B (11) 3.11(1) 350 °F/177 °C 350 °F/177 °C 610 °F/321 °C YES
EX-1522 Epoxy 0.011 3.3B 0.008 2.80 350 °F/177 °C 356 °F/180 °C N/A YES
BT250E-1 Epoxy 0.011 3.40 0.019 3.00 250 °F/121 °C 257 °F/125 °C N/A YES
TC250 Epoxy 0.012 3.49 0.021 3.00 275 °F/135 °C 285 °F/140 °C 356 °F/180 °C YES
RS-8HT BMI 0.014 3.49 0.007 3.01 350 °F/177 °C 482 °F/250 °C 397 °F/203 °C 545 °F/285 °C NO

*In order of laminate loss tangent. Test method ASTM D2520.

(1) At 1MHz (2) Thermoformable (3) At 6.5 GHz (4) At 35 GHz
*See www.tencate.com for individual data sheets for properties and process information.

PREPREG REINFORCEMENTS Sp. Gravity (g/cc) Moisture Pickup (% by Wt.) Service Temp. Applications
Reinforcement Dk (10 GHz) Df (10 GHz) Aircraft Ground Systems Spacecraft Missiles
“E” Fiberglass 6.10 0.004 2.55 nil 700°F
“S” Fiberglass 5.21 0.006 2.49 nil 750°F
Quartz 3.78 0.0002 2.20 nil >1000°F
HDPE 2.00 0.0004 0.97 nil 220°F
LMR Kevlar® 49(1) 3.85 0.008 1.47 1.9% 350°F

(1) LMR Kevlar® 49 is a special TenCate proprietary product which treats the Kevlar fiber such that moisture absorption is greatly reduced. LMR is our Low Moisture Regain designation for this material.

ADHESIVES & SYNTACTICS Neat Resin Quartz Laminate
Product Name Resin Type Dielectric Constant Loss Tangent Dielectric Constant Loss Tangent
Film Adhesives Dk Df Dk Df Cure Temp. °F/°C Cure Time Min Tg °F/°C
EX-1516 Cyanate Ester 2.8 0.008 N/A N/A 250 °F/121 °C 300 min 258 °F/126 °C
EX-1543 Cyanate Ester 2.72 0.009 N/A N/A 350 °F/177 °C 120 min 405 °F/207 °C
RS-4A Cyanate Ester N/A N/A N/A N/A 350 °F/177 °C 120 min 397 °F/203 °C
TC4015 Cyanate Ester N/A N/A N/A N/A 350 °F/177 °C 120 min 610 °F/321 °C
Syntactic Film or Paste
EX-1541 (11 pcf) Cyanate Ester Paste 1.32 0.009 N/A N/A 350 °F/177 °C 120 min 350 °F/177 °C
EX-1541 (13 pcf) Cyanate Ester Paste 1.32 0.009 N/A N/A 350 °F/177 °C 120 min 350 °F/177 °C
SF-5 (38 pcf) Cyanate Ester Film 1.7 0.004 N/A N/A 350 °F/177 °C 120 min 490 °F/254 °C
TCF4001 (22-26 pcf) Cyanate Ester Paste 1.55 0.012 N/A N/A 350 °F/177 °C 120 min 350 °F/177 °C
TCF4035 (40 pcf) Epoxy Film 1.94 0.018 N/A N/A 265 °F/130 °C 180 min 284 °F/140 °C
TCF4045 (35.5 pcf) Cyanate Ester Film 1.57-1.84 0.008 N/A N/A 355 °F/179 °C 180 min 356 °F/180 °C
TCF4050 (69 pcf)3 Cyanate Ester Core Splice N/A N/A N/A N/A 350 °F/177 °C 120 min 350 °F/177 °C

(3) Unexpanded density

Carbon-Free Production for Low-Dielectric Materials

TenCate Advanced Composites is proud of its advanced carbon-free production facilities. The company’s production floor has been specially equipped for the fabrication of radome-qualified composites.

Production for Low-Dielectric Materials

Production for Low-Dielectric Materials

The company’s facilities have the following features:

  • Precision prepregging and precision filming capability
  • Full computer controlled process parameters
  • Exclusive environmentally controlled carbon-free area with positive ventilation for quartz, glass and electronic products

World Leading Radome Composite Materials

A radome is a cover designed to safeguard an antenna system from the environment, while also, in certain cases, providing lightning strike protection, aerodynamics and stealthy features. Choosing the ideal composite materials is important for maintaining the radome-antenna system.

Applications include ship, rail, military and civil aircraft, and ground-based systems, including conformal or “patch” antennas.

In flight, a military aircraft will interface with more than fifteen antennas with numerous functions such as weather detection, ground communication, sat com, jammer pods, target acquisition, fire control, ground imagery and altitude monitoring, etc.

Trend Towards Higher Frequencies

Progressively, antenna systems are multifunctional, operating “broadband” over numerous different frequencies, with a trend towards the higher frequency bands. Not only are the lower frequency bands just filling up, but operating at a higher frequency (for example Ka instead of Ku band for Wi-Fi) permits high-speed transmission of “big data”. Streaming video on board planes will be more achievable with Ka band communications.

The increasing advancement of antenna systems drives complexity in the radome design, requiring “B-Sandwich” and “C-Sandwich” constructions for Wi-Fi radomes, demanding higher performance advanced composite materials, such as epoxy/quartz, or cyanate ester/quartz, in place of E-glass/ epoxy.

TenCate’s cyanate ester and epoxy based prepregs, adhesives and syntactic foams, RTM resin systems, feature low density, low dielectric loss tangent, low moisture absorption, low dielectric constant and low coefficient of thermal expansion.

Radome & Antenna Composites

Understanding Dielectric Constant and Loss

Signal fade or “loss” occurs either by reflection of the signal from the surface of the composite or via absorption by heating of the matrix.

The dielectric constant (Dk) offers an idea of the reflective properties, as well as the refractive properties of a material. Simplistically, the signal can be thought of “slowing down” as it moves through the composite (compared with air). If the signal hits a surface at an angle, it will be deflected; this is labeled “boresight error” or “beam deflection”.

Dielectric constant and loss together specify the transmission efficiency of a radome antenna system and are ideally measured at the intended operating frequencies. The lower the dielectric constant and loss, the lower powered the antenna systems have to be, and the smaller the effect of the radome on the antenna performance. TenCate Advanced Composites has a wide-ranging database of materials tested over numerous different frequencies, to help improve the radome design. This data is fed to computer-aided electromagnetic modeling packages and is a main factor in the performance of the radome antenna system.

BEST PERFORMANCE BEST COST
Cyanate Ester / Quartz Fabric Low Dielectric Epoxy / Quartz Fabric Low Dielectric Epoxy / Glass Fabric
Electrical Performance BEST
Dielectric Constant 3.2 to 3.35
Loss Tangent 0.001 to 0.009
BETTER
Dielectric Constant 3.4 to 3.8
Loss Tangent 0.009 to 0.011
GOOD
Dielectric Constant 4.5 and above
Loss Tangent 0.011 and above
Laminate Impact Strength VERY GOOD VERY GOOD MODERATE
Laminate Moisture Absorption LOWEST 0.1 - 0.6% VERY LOW 0.6 - 0.8% MODERATE 1.2 - 1.6%

Radome & Antenna Composites

TenCate Composite Laminate Performance over C/X, Ku/K, Ka and Q/U Bands

Laminate performance over different band frequencies Frequency
C/X Band: 4-8 GHz X Band: 8-12 GHz Ku/K Band: 12-26.5 GHz Ka Band: 26.5-40 GHz Q & U Band: 40-60 GHz
Product Name1 Resin Type Reinforcement Open Resonator3 Open Resonator3 Focus Beam method Open Resonator3 Focus Beam method Open Resonator3 Focus Beam method Focus Beam method
Dk DF Dk DF Dk DF Dk DF Dk DF Dk DF Dk DF Dk DF
BTCy-2 Cyanate Ester 4581 quartz N/A N/A N/A N/A 3.17 0.010 N/A N/A 3.13 <0.012 N/A N/A 3.14 <0.012 3.12 <0.012
BTCy-1A Cyanate Ester 4581 quartz 3.26 0.004 3.27 0.004 3.23 0.013 3.23 0.004 3.18 <0.012 3.24 0.004 3.19 <0.012 3.18 <0.012
EX-1515 Cyanate Ester 4581 quartz 3.24 0.005 3.24 0.005 N/A N/A 3.21 0.005 N/A N/A 3.19 0.005 N/A N/A N/A N/A
EX-1522 Epoxy 4581 quartz 3.35 0.005 3.34 0.005 3.35 0.011 3.32 0.005 3.31 0.011 3.32 0.005 3.31 <0.012 3.31 <0.012
TC250 Epoxy 4581 quartz 3.45 0.013 3.45 0.013 3.47 0.015 3.43 0.012 3.43 0.015 3.40 0.012 3.42 0.011 3.40 0.012
BT250E-1 Epoxy 7781 E-glass 4.61 0.014 4.57 0.015 4.52 0.019 4.47 0.016 4.48 0.018 4.50 0.020 4.45 0.017 4.42 0.016
EX-1522 Epoxy 7781 E-glass 4.68 0.009 4.69 0.010 4.72 0.012 4.65 0.011 4.67 0.013 4.63 0.013 4.66 0.010 4.64 0.011
TC250 Epoxy 7781 E-glass 4.83 0.016 4.82 0.016 4.73 0.026 4.78 0.016 4.63 0.023 4.73 0.017 4.64 0.016 4.59 0.019

1. In order of laminate Dielectric Constant for X Band using Focus Beam Method.
2. Focused Beam loss tangent results are not precise < 0.010 DF. These materials represent TenCate’s best candidates for high energy radome applications.
3. Open Resonator results using ASTM D2520 Method C.

Dk - Dielectric Constant
DF - Loss Tangent

Adhesives and Syntactics

Resin Type Dry Tg Onset (DMTA) Cure Time and Temperature Material at 10 GHz OOA / VBO Toughened
Dielectric Constant (Dk) Loss Tangent (DF)
SYNTACTIC FILMS
SF-5 Cyanate Ester 193 °C (380 °F) or 254°C (490°F) with post cure 2 hours at 120°C (350°F) Optional post cure of 2 hours at 232°C (450°F) 1.704 0.004
TCF4045 Epoxy 180 °C (356 °F) 3 hours at 179 °C (355 °F) 1.57 0.008 ο
TCF4035 Epoxy 140 °C (284 °F) 3 hours at 130 °C (265 °F) 1.94 0.018 ο
TCF4050 Cyanate Ester 176 °C (349 °F) or 232 °C (450 °F) with post cure 2 hours at 177 °C (350 °F) Optional post cure of 60-90 minutes at 232 °C (450 °F) N/A N/A ο
FILM ADHESIVES
EX-1516 Cyanate Ester 126 °C (258 °F) 5 hours at 121 °C (250 °F) 2.6 - 2.7 0.005 - 0.006 ο ο
EX-1543 Cyanate Ester 207 °C (405 °F) 2 hours at 177 °C (350 °F) Optional post cure of 2 hours at 204 °C (400 °F) 2.72 0.009 ο ο
TC263 Epoxy 110-115 °C (230-239 °F) 2 hours at 121 °C (250 °F) 2.97 0.017 ο ο
TC310 Epoxy 157 °C (315 °F) 2 hours at 177 °C (350 °F) 3.06 0.013 ο ο
RS-4A Cyanate Ester 203 °C (397 °F) 2 hours at 177 °C (350 °F) N/A N/A ο ο
TC4015 Cyanate Ester 176 °C (349 °F) or 321 °C (610 °F) with post cure 2 hours at 177 °C (350 °F) Optional post cure for >60 minutes at 232 °C (450 °F) N/A N/A ο ο
SYNTACTIC PASTES
EX-1541 Cyanate Ester 227 °C (441 °F) or 240 °C (464 °F) with post cure 2 hours at 177 °C (350 °F) Optional post cure of 2 hours at 232 °C (450 °F) 1.32 0.009
TCF4001 Cyanate Ester 176 °C (349 °F) 2 hours at 177 °C (350 °F) Optional post cure of 60-90 minutes at 232 °C (450 °F) 1.55 0.012 ο

4. SF-5 tested at 18 GHz

Common Prepreg Reinforcements

Dk (10 GHz) DF (10 GHz) Sp. gravity (g/cc) Moisture pickup (% by Wt.) Service temp.
E-glass 6.10 0.004 2.55 nil 371 ºC
(700ºF)
S-glass 5.21 0.006 2.49 nil 398 ºC
(750 ºF)
Quartz 3.78 0.0002 2.20 nil >537 ºC
(>1000 ºF)
HDPE 2.00 0.0004 0.97 nil 104 ºC
(220 ºF)
LMR Kevlar® 495 3.85 0.008 1.47 1.9% 176 ºC
(350 ºF)

5. LMR Kevlar® 49 is a TenCate proprietary Low Moisture Regain treatment of the aramid fabric from E.I. de Pont de Nemours and Company.

Resin System Performance

Resin type Dk (10 GHz) DF (10 GHz)
BTCy-2 Cyanate Ester 2.70 0.001
BTCy-1A Cyanate Ester 2.70 0.003
EX-1515 Cyanate Ester 2.79 0.004
EX-1522 Epoxy 2.71 0.007
RS-8HT BMI 3.01 0.0074
RS-3C Cyanate Ester 2.816 0.0096
TC420 Cyanate Ester 3.11 0.016
BT250E-1 Epoxy 3.00 0.017
TC250 Epoxy 3.00 - 3.06 0.020 - 0.021

Block wave results using test ASTM D 2520 Method A
6. Sample tested at 10.7 GHz using Open Resonator test ASTM D 2520 Method C

Manufacturing Facilities

TenCate operates positively pressurized enclosed rooms housing the carbon free machines and equipment devoted solely to the manufacture of radome prepregs and complementary products.

The carbon free facilities do not run carbon fiber prepregs and are isolated from conductive materials, thus assuring outstanding quality and electrically pure products. Even a tiny carbon fiber contaminate in a radome will heat up in reaction to an electromagnetic signal, and can deform the matrix around it.

TenCate Advanced Composite materials from the carbon free lines are used in antennas, sonar domes, reflectors, components with embedded de-icing elements, conformal radomes, microwave transparent and radar absorbing structures. Popular reinforcements such as S2 glass, quartz, E-glass and aramid are totally compatible with TenCate’s advanced resin systems and can be provided as prepregs to satisfy the most challenging mechanical, electrical and high-temperature applications.

Manufacturing Facilities

Technologically Advanced Triband Satcom Radome

The General Dynamics LiveTV radome is a technologically progressive composite satcom radome. Engineered to convey data across three bandwidths (K, Ka, and Ku), the radome realizes improved levels of speed and connectivity for two-way communications and inflight Wi-Fi.

TenCate Advanced Composites worked along with General Dynamics, the radome designer and manufacturer, in delivering a material solution that would permit the enclosed antennas to communicate and receive radio frequency signals across a wider range of bandwidths. Other design considerations included longevity, reliability in signal transmission across all parts and cost effectiveness.

The TenCate TC250 is an epoxy-based thermoset prepreg that offers an exceptional balance of toughness, mechanical property translation, low dielectrics and hot/wet performance. Incorporated with a quartz fabric, this advanced composite material solution offered superior mechanical performance while preserving cost effectiveness.

Triband Satcom Radome

About Tencate Advanced Composites

TenCate is a multinational company that combines textile technology with related chemical processes. Tencate develop and produce specialist materials with specific properties. Protective materials for fire-fighting clothing and strong, lightweight materials in aircraft are good examples of these, as are materials that block UV radiation for applications like tentcloth and awnings.

TenCate’s activities can be divided into four areas of application:

  • Safety and protection
  • Aerospace
  • Sport and recreation
  • Infrastructure and the environment

TenCate has divided these segments into the eight divisions:

  • Protective Fabrics
  • Outdoor Fabrics
  • Space Composites
  • Aerospace Composites
  • Industrial Composites
  • Advanced Armor
  • Geosynthetics
  • Industrial Fabrics
  • Grass

For additional technical information, please contact TenCate by email at [email protected].

TenCate Advanced Composites

This information has been sourced, reviewed and adapted from materials provided by TenCate Advanced Composites.

For more information on this source, please visit TenCate Advanced Composites.

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