Antenna Range Design & Evaluation

 

The Howland Company has been involved in antenna range design since the company was founded. The first antenna ranges were outdoor ranges with tall towers at either end in order to minimize the effects of reflections from the range surface. Later the development of wide band microwave absorber allowed the design of indoor chambers, but it was only practical to test relatively low gain antennas in these facilities. The invention of the compact range gave engineers the ability to test high gain antennas indoors. Finally, the development of near-field techniques completed the portfolio of available choices.

In spite of all the techniques available to test antennas, there is not one general purpose range that will test every type of antenna. One must look at the characteristics of the antenna to be tested and decide which test method is most suitable.

The Howland Company's role has been to recommend the appropriate test method and then to design the physical parameters of the antenna range to meet the specific test requirements.

Outdoor Ranges


Indoor Ranges


Compact Ranges


F-22 Antenna Calibration Range
 --Photo by John Carnett for Popular Science Magazine
Photo by John Carnett
Antenna Calibration Range for the F-22
 

This range at Lockheed Martin is used to develop calibration data for the EW and CNI antenna suites for each F-22 aircraft. The Howland Company designed the anechoic chamber and facility layout, developed a design concept for test antenna fixtures and test article handling, assisted Lockheed and the instrumentation suppliers with the development of the measurement software, and prepared the procurement specifications for the specialized antenna fixtures and their transporters. The chamber dimensions are 60 feet x 110 feet x 45 feet high.

 
 

Outdoor Ranges

Although simple in concept, there are many important details to consider in the design and layout of an outdoor antenna range.

Unfortunately, there is not a universal antenna range. Antenna ranges are designed for specific classes or types of antennas. A range designed for a high frequency fire control radar will not make accurate measurements of a low gain communications antenna.

An antenna range design starts with the antenna to be tested. From its size and operating frequency the antenna range designer can determine the range length, tower heights and source antenna characteristics.

And of course there are always tradeoffs to be made between the cost of the range and the acceptable level of uncertainty (precision) of the measurements the range is capable of making.

We have developed solutions for a number of clients, including Ford Aerospace, Motorola, Gabriel, and NASA's Jet Propulsion Lab. The Howland Company can also provide evaluations of existing outdoor ranges, including field probing and problem identification and resolution.

     
The Howland Company designed, manufactured, and installed a unique collection of outdoor antenna range equipment to provide Motorola with a state-of-the-art, multipurpose antenna range complex. The 2-acre site encompasses a 300-foot elevated range, a 200-foot ground reflection range, a 30-foot radius spherical near-field scanner, and a range control building with lab space and an enclosed impedance measurement area.   The Howland Company designed this multi-axis outdoor antenna range for development and production testing of a wide range of antennas for commercial and military communications, satellite earth stations, and radar and air traffic control systems, and other applications.

Antenna Range Complex,
Motorola World Headquarters

 

Outdoor Multipurpose Antenna Range,
RSI Technical Products

 

Outdoor antenna range for JPL--gain measurement verification system
 --Photos by Ray Howland and JPL
 

The Howland Company collaborated with NASA's Jet Propulsion Lab in the design, development, and use in experiments of this 5000-foot outdoor range as part of a project for the Deep Space Network. Pairs of 6-foot reflector antennas on the edge of the 26-meter DSS-13 parabolic reflector antenna (inset right) and on a collimation tower on the horizon down-range (inset left) were part of a technique we developed and used to measure multipath and time delay errors encountered in the use of the large antenna system for Very Long Baseline Interferometry (VLBI) measurements. (The white diode array between the two dishes on the tower was from a microwave power transmission experiment conducted several years earlier.)

 
 
 

1700-foot antenna range, Gabriel Antenna, Scarborough, Maine
 --Images from Bing Maps

Gabriel Electronics, a leading manufacturer of horn reflector microwave antennas for point-to-point transmission systems, asked The Howland Company to design a high-performance, outdoor antenna range for evaluation of antennas used on high-density, long haul common carrier systems. We designed the antenna range for measurement of low sidelobe levels and high front-to-back ratios. We also assisted Gabriel in obtaining local zoning approval for the facility. Once the instrumentation was installed, we evaluated the range to verify that it met predicted performance levels.

 
 

Ford Aerospace Intelsat range, Milpitas, California
 --Inset photo and range diagram by Jud Lyon

The Howland Company designed this 8000-foot automated test-on-transmit antenna range for Ford Aerospace to test Intelsat IV and V satellite antennas. We prepared a conceptual design for an automated, 10d2/λ, multi-band test facility; designed an anechoic test cubicle with a low return loss radome (inset); designed and built special instrumentation required for test-on-transmit and a 10,000-foot range cable to carry control signals in one direction and signal and reference data in the other. We also coordinated test frequencies with existing commercial services and predicted the range's measurement uncertainty.

PDFDownload "The Design of an Automated, High-Accuracy Antenna Test Facility" by Jud Lyon and Ray Howland, IEEE I&M, March 1983 (816k PDF)

 

Indoor Ranges - Anechoic Chambers

Advanced System Integration Lab
 --
 

Anechoic chambers are widely used by manufacturers of both defense and commercial products. Sometimes their purpose is to keep extraneous signals from interfering with a measurement, and at other times they are used to protect sensitive information from outside sources.

The Howland Company has designed and evaluated all types of anechoic chambers, from the extremely large to the fairly small. We have also been tasked with evaluating existing chambers and then improving their performance. We have an established track record of finding imaginative and cost-effective solutions to complex problems.

 
Tapered Anechoic Chamber, NSWC Dahlgren--tilting azimuth turntable, dielectric mast, and standard gain horn
Tapered Anechoic Chamber, NSWC Dahlgren--after replacement of RF absorber
US Navy photo   PELI photo
 

Tapered Anechoic Chamber, NSWC Dahlgren

The Howland Company performed 'before' and 'after' field probes and did extensive troubleshooting
to bring this 100 x 27 x 27 foot chamber back to optimum performance after all of its RF absorber was replaced.

 
 
The main compact range reflector in Sandia National Labs' RCS range. Sandia National Labs Compact Range - Sandia engineers developed this dual reflector 'folded compact range' configuration to support ISAR measurements of sample ground surfaces, such as detection of footprints or tiretracks in sand or gravel.
SNL photos
 

Indoor Range for RCS Measurements, Sandia National Labs

In the mid-eighties, The Howland Company designed one of the world's first indoor RCS ranges for Sandia National Labs. The facility includes a 110 ft x 42 ft x 26 ft (34m x 13m x 8m) anechoic chamber, compact range, and a host building with special provisions for seismic and environmental isolation. We prepared drawings and specifications related to the electromagnetic design; provided coordination between Sandia's facilities engineers, the building contractor, and the instrumentation system supplier; and wrote the range acceptance test procedure. We also designed and built a transportable 12-foot NRL arch, which we used to perform on-site acceptance tests--normal, high incidence, and bistatic--on all 4300 pieces of RF absorber used in the facility. In 2008, a series of upgrades to the facility were made to ensure its central role in Sandia's R&D work for many years to come.

 
 

Compact Ranges

Originally developed by Scientific-Atlanta in cooperation with The Georgia Institute of Technology, the compact range has become a very useful tool for antenna, radome and RCS measurements.

In its simplest configuration, the compact range uses a parabolic reflector to generate a plane wave suitable for antenna measurements. Dual reflector systems were subsequently developed by March Microwave and MBB (now EADS Astrium) to enhance certain characteristics.

The Howland Company has been involved in numerous compact range projects over the last 30 years. These projects included compact ranges used for antenna, radome and RCS measurements. Typically we have been responsible for the overall electromagnetic design, including the design of the anechoic material and the shielding. Frequently our role also includes developing a conceptual design and procedures for the test article handling system.

We have also been used as an independent source of technical review and bid review, and we have provided an unbiased evaluation of the quiet zone characteristics.

Setting up a measurement of a Bi-Static RCS Compact Range, US Navy, Point Mugu

US Navy photo.
Compact Range for Bi-Static RCS Measurements,
US Navy Air Warfare Center Weapons Division,
Point Mugu, California
 

Electromagnetic Test Facilities, Hughes Aircraft

Compact Range for Radome Test System, Robins AFB
 --THC Photo by Jim Howland
Hughes Aircraft photo  

Dual-Reflector Compact Range
for RCS Measurements, Hughes Aircraft,
El Segundo, California

Compact Range for Precision Radome
Test & Measurements, US Air Force, Warner Robins
Air Logistics Center, Georgia

   
F-16 FCRATS depot test system, Ogden ALC at Hill AFB F-16 NRETS depot test system, Ogden ALC at Hill AFB
Both photos courtesy Scientific-Atlanta
 

The Howland Company provided system integration and system engineering services for two compact ranges used for depot maintenance of the F-16 at Hill AFB in Utah. The F-16 Fire Control Radar Automated Test System (FCRATS) (right) and Nose Radome Electrical Test System (NRETS) (left) were completed in the mid 1980s and, with digital instrumentation upgrades, continue to support the F-16 fleet.