Antennas for Communications (AFC) Logo Radome Capabilities


Return to Radome Network Home Page Return to Radome Network Home Page

Advantages of Radome Protection

Radar domes, or Radomes, are RF window structures used to shelter antennas. Typical applications include antennas for radar, telemetry, tracking, communications, surveillance, and radio astronomy. The first radome was constructed 40 years ago; they are currently in use throughout the world, from the tropics to the arctic.

The principal purpose of a radome is to shield the antenna from the environment. This improves system availability since the antenna is not affected by winds, rain, or ice. It can also improve antenna performance since high winds or temperature variations can distort the shape and pointing direction of the reflector or phased array.

Radomes also provide a benign environment for any electronics, and personnel, that must be located near the antenna. This is especially significant in harsh weather, such as temperature extremes, blowing sand or dirt, salt spray, and freezing rain.

Radomes have proven to be very effective when considering life cycle costs. Since the antenna is in a protected environment, maintenance costs are held to a minimum. The structural requirements of the antenna are less stringent, resulting in reduced fabrication and installation costs plus the use of smaller positioning motors.

Further, a unique advantage of radomes are that dome structures are aesthetically pleasing. Radomes are also very effective in concealing the type of equipment inside the dome.

Table of Contents

Basic Construction Techniques

Rigid radomes are designed using the principles of a geodesic dome. This technique uses straight or circular arc structural elements in tension, arranged in a framework of geometric patterns such as triangles and hexagons. This design results in a structure that provides maximum volume with minimum material, reduces stress and weight, and may be tailored to meet exacting electromagnetic scattering requirements.

Thin Membrane Wall Dielectric Radome 3-Layer Sandwich Dielectric Radome 2-Layer Sandwich Dielectric Radome

AFC currently offers four different types of rigid radomes: the thin membrane wall dielectric space frame (DSF), the composite laminate and the two and three layer composite sandwich foam core DSF radome. The term Dielectric Space Frame with acronym DSF refers to the dielectric panel flanges surrounding the panel wall, which forms a framework characteristic of the panel shapes. Each radome type provides unique operating characteristics and benefits. Although all types may be used in a variety of different applications, the sandwich foam core approach accommodates a temperature compensated environment for electronics or personnel. Radome size varies from several inches to 150 ft. in diameter. For more details, see
advantages of dielectric radome technology.
Table of Contents

Design Enhancements to Maximize Performance

Antenna design engineers believe their antennas are perfect creations. Therefore, the ideal radome would appear totally transparent to any electromagnetic signal. Since this is not possible, radomes must be designed to minimize the impact of the radome on the enclosed antenna. Application requirements determine the importance of signal distortions such as insertion loss, boresight error, and scattering into the antenna sidelobes. AFC employs several different techniques to improve performance goals.
Table of Contents

Random Panel Geometry Eliminates Coherent Reflections

Radome Geometry Radome geometry framework panel members cause scattering transmission loss errors whenever the framework shadows the antenna aperture. If the radome were constructed of identical panels, the total scattering loss would be summed by the repeated error. To eliminate this problem, many AFC radomes utilize a quasi-random or pseudo-random panel design.

Random panel design is achieved by starting with one of the Platonic Forms; which is a method of dividing a sphere into 4, 6, 8, 12, or 20 identical subdivisions. One of the subdivisions is then further divided into panels of different shapes. By repeating this pattern, a complete sphere can be constructed that will provide the quasi-random panel distribution without extensive fabrication costs.

Table of Contents

Tuning a Dielectric Radome

Radome Impedance Match Example The thin wall dielectric space frame, composite laminate and sandwich foam core DSF radomes are assembled from multiple panels. At the panel edges, the dielectric is reinforced into flanges to support structural loads and mechanical fasteners. Assembled, the panel edge flange frameworks act as capacitive loaded dielectric strut antenna elements, scattering signals according to radome panel geometry, strut thickness, frequency and the enclosed antenna pattern and polarization. Scattering loss is often 4 to 100 times larger than the ordinary wall insertion loss. To compensate the scattering loss, AFC impedance matches, "tunes", the radome framework by embedding circuits into the framework. The inductive circuits cancel the capacitance of the dielectric struts. To even further help reduce the influence of strut scatterers, panel geometry is chosen to minimize boresight shift and sidelobe perturbations.
Table of Contents

Frequency Matching a Sandwich Radome

The sandwich radome panels consist of a foam core sandwiched between two thin sheets of fiberglass skin layers. This technique provides excellent thermal insulation and minimal transmission losses at selected frequencies. The insertion loss of sandwich material is a function of the thickness of the core. By varying the thickness, optimal performance is achieved for the particular frequency band of interest.
Table of Contents

Eliminating Water Accumulation

Additive Rain Transmission Loss Additive Rain Noise Temperature
Additive rain transmission loss Additive rain noise temperature

With any radome, water will tend to collect on the exterior surface and run off in sheets; significantly affecting performance. AFC utilizes a proprietary technique to provide a long lasting
super-hydrophobic surface, called Hydrolam 2000. This causes the radome to remain dryer, water to bead and run off in rivulets instead of sheeting. A hydrophobic surface significantly reduces ice adhesion.

Table of Contents

Mechanical and Structural Considerations for Radome Lifetime

Independant of the radome type, sandwich or composite laminate, the same number of panels are required. In a typical design, maximum panel dimensions are chosen for worldwide shipment. This permits use of a standard ISO ocean shipping container and trucks and simplifies panel handling during installation.

Most radomes are designed to operate with wind speeds of up to 67 m/s (150 mph), and snow or ice loading of up to 235-kg/m2 (50-lb/ft2). To minimize electromagnetic, RF degradation, radome structural strength must be measured against the demands for better RF performance. What this means is that the radome structure supporting the wind, snow and ice loads must be designed just strong enough to meet environmental requirements for the radome lifetime. Beefing up the radome panel framework or making the wall sturdier degrades RF performance. To enhance RF performance, this balancing act between a stronger structure with heavy-duty sized members and RF performance determines that radomes are designed with structural safety factors determined by radome lifetime requirements. It is for this reason that AFC has defined radome structural safety factors by a criterion based on a minimum radome 20-year lifespan with General Buckling Safety factor greater than >1.9.

The structural load bearing capabilities of a radome are a function of radome diameter and geometry, frequency, number of panels and both the flange and wall design in conformance to the radome RF performance. As a result, each radome is customized to match your particular system environmental requirements over the lifetime of the radome.

Table of Contents

Selecting a Radome to Match Your Requirements

In most applications the two primary factors in selecting the type of radome are performance and cost. Additional considerations may include ease of transportation, installation, snow loading and wind/gust rating. All applicable factors must be considered in order to insure an optimum match.
Table of Contents

Operating Frequency Considerations

In general, thin membrane and sandwich wall dielectric space frame radomes are considered broad band structures suitable for operation over a relatively wide range of frequencies. Sandwich radomes are more frequency specific since the thickness of the core is varied to achieve the desired insertion loss for a particular frequency band. In general, the sandwich radome frequency response forms a low pass filter with the cut-off frequency corresponding to the upper frequency limit.
Table of Contents

Relative radome cost

Initial Cost Approximation

The initial cost of a radome is primarily dependent on the size of the structure and increases as the radome surface area (radome diameter D2). Note that the material and labor costs in a radome will increase geometrically with the diameter. This is due to the fact that doubling the diameter of a sphere will increase the surface area by a factor of four. As calculated in the Relative Cost comparisons, thin wall dielectric space frame radomes are approximately 15 percent less expensive than a comparable sandwich core radome.
Table of Contents

 

Complete Radome System Capability

In addition to radome design and fabrication, AFC also offers a complete turn-key system capability. This includes complete installation, performance verification, support equipment, and extended term maintenance. The only aspects not covered by AFC are the antenna design and the site selection. These two items are normally dictated by the mission to be performed.
Table of Contents

Installation Services Throughout the World

68-ft. Diameter Dielectric DSCS Radome View 1. 68-ft. Diameter Dielectric DSCS Radome View 2. 68-ft. Diameter Dielectric DSCS Radome View 3.

AFC maintains an installation team with the experience and capability of installing a radome at any site in the world. Typical services include foundation design requirements, radome assembly, and performance verification. Extended term maintenance contracts are available for our radomes. These contracts cover both preventive maintenance and repair. The repair aspect frequently includes fabricating replacement panels or accessories.

Table of Contents

Support Equipment for Full Operational Status

Support equipment typically includes ac power distribution, interior lighting, heating/air conditioning, aircraft warning lights, lightning protection, and interior support for hoists and other mechanical devices. AFC will provide and install all required support equipment to insure that the system achieves full operational status within a minimum time frame. AFC also maintains an inventory of standard support equipment to insure a fast response to any failure.
Table of Contents

Advantages of Selecting AFC as Your Radome Source

Most radome solutions may be customized from standard off-the-shelf COTS units. In some cases, radomes must be individually designed and fabricated to satisfy a unique set of requirements. Accomplishing design requirements in a timely manner requires practical experience, engineering talent, facilities, effective administration, and a willingness to commit all of these resources to the task.
Table of Contents

Experience of Over 30 Years

In 1979 Microdyne acquired Antennas For Communications (AFC), an antenna manufacturing company started in 1972. This acquisition enabled Microdyne to offer complete systems for both uplink and downlink satellite communications. In June 1991, AFC was purchased by an employee group.

Table of Contents

Capabilities to Match Your Fast Response Requirements

AFC has the engineering, manufacturing, and administrative capabilities to respond to your requirements. For example, AFC signed a "quick reaction" contract to design and fabricate two, 41 foot (12.6m) dielectric space frame radomes for the US Army. The radomes were completed and ready for shipment 60 days after receipt of the order. An additional three weeks was required for installation and full performance verification. This example is typical of AFC willingness to commit their resources to meeting your requirements.
Table of Contents

Quality to Last

AFC's quality control manufacturing standards are certified under ISO 9001 : 2008 and supports FAA-STD-016A and MIL-I-45208A Quality Program Requirements. Custom-tailored to insure compliance....fabrication process controls and program tests, record and data audits....at each and every step in radome implementation. This assures top quality, in all aspects, of the final product.
Table of Contents

Related Standard and Specialized Products

Antennas for Communications offers specialized products to provide superior performance in a variety of applications. These products include antennas and waveguide components.
Table of Contents

Standard and Customized Antennas

AFC's standard antenna line includes conical horn and dish antennas from one to five meters in diameter. These antennas are currently in use throughout the world for a wide variety of commercial and government customers. The primary applications include microwave links, Television Receive Only (TVRO) downlinks, and satellite uplinks.

AFC also maintains a complete design and fabrication capability to provide custom antennas for specialized applications. Since this capability is an integral part of the company, AFC is able to provide a fast response for customized antennas at a competitive price.

Table of Contents

Turnkey Shelters for Specialized Applications

Typical examples of turnkey AFC shelters are transportable up-links and "quick reaction" secure airborne deliverable shelter modules. The uplinks, used by most major television stations, consist of the truck, the transmitting antenna, and the shelter equipped with all necessary electronics. Secure shelters are customized to meet customer objectives and shipping dates and are often configured with environmental controls, appropriate electrical filtering, electronic racks, power distribution, back-up power system and antennas. AFC engineers, along with customer personnel, team to evaluate shelter electronics subsystems where classification permits. Fixed station uplinks are also available for video, audio, voice and data.
Table of Contents

Custom Waveguide Components and Low Loss Transmission Lines

Custom waveguide components include multi-band feeds, rotary joints, filters, diplexers, OMTs, rectangular to circular converters, special bends and twists, and other custom hardware. Applications serve ground based, airborne and spacecraft environments.

The Tallguide® product line consists of a series of oversized waveguides, mode suppressors and transitions which provide exceptionally low transmission losses in comparison to standard waveguide. The attenuation per 100 feet is typically one-tenth of conventional waveguides. This increased efficiency can result in a significant reduction in system costs. The product line includes all necessary hardware for operation in the 5 to 100 GHz frequency range.

AFC manufactures, markets and sells worldwide satellite dish antennas, conical horn antennas, radomes, antenna feeds, microwave and waveguide components, ultra low loss waveguide transmission line Tallguide ®, and shelters. Our customers serve the broadcast, communications, radar, weather and cable industry, defense, government, and government agencies worldwide. AFC's quality control manufacturing standards are certified under ISO 9001 : 2008.

A complete Internet WWW AFC site index may be found in Antennas for Communications (AFC) Home Page Document Summary List.

Table of Contents   Top of Page   Return to Radome Network Home page Return to Radome Network Home Page

Antennas for Communications
2499 SW 60th Ave, Ocala, FL 34474
Telephone (352) 687-4121 Fax (352) 687-1203 E-mail sales@afcsat.com


Tallguide is a Registered Trademark of Antennas for Communications
Copyright © 1996 - 2016 Antennas for Communications