Antenna Range Complex, Motorola
World Headquarters, Schaumburg, Illinois

     

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 site, which occupies a space of only 360 by 240 feet, 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 project began in 1994 when Motorola approached The Howland Company with their requirement to relocate existing outdoor ranges, made necessary by capital improvements on the Schaumburg campus, and their interest in acquiring a new spherical nearfield scanner for measuring vehicle-mounted antennas. Howland engineers worked with Motorola engineering and facilities groups to define requirements for the new ranges, identify potential sites on the Motorola campus, and establish performance requirements for the spherical nearfield system. An important consideration was the need to refurbish and reuse as much of the existing antenna range equipment as possible, in order to stay within the project's budget.

 

Howland also worked closely with Motorola's architect and construction contractors to monitor construction and civil work. Howland engineers reviewed the project drawings and met frequently with the architects and construction managers to insure that all the construction and site work details were understood and properly executed. In addition to the range control building, site work included the foundation and guy anchors for the 300-foot range's source tower, the foundation and pits for the spherical nearfield scanner, and a sloped 8-foot high berm to shield the range site from an adjacent employee parking lot.

 

The following paragraphs describe the main components of the range complex:

Control building. The 900 square foot, single story range control building is oriented on the range site to minimize reflections from the walls into the range area. The AUT end of the 300-foot elevated range is located on a deck on the building’s roof. A vertical probe positioner mounted on the corner of the building serves as one end of the 200-foot ground reflection range. An enclosed area constructed of dielectric materials on the rear of the building permits year-round impedance measurements on full-size cars and trucks. In addition to space for the range control equipment, the building provides ample shop space for fabricating test fixtures and prototypes.

 

Range Control Building, Motorola Antenna Range Complex

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Elevated range. The 300-foot range uses Motorola’s existing Scientific-Atlanta Model 53230B azimuth-over-elevation positioner and 58620 model tower. These are located on the control building roof, to place the AUT at 30 feet above ground. At the other end of the range is a 43-foot Howland Model FP42S source tower. The tower can support an antenna weight of up to 850 lbs., and can operate safely in a 40 mph wind with a 10-foot reflector antenna mounted.

 

The tower’s vertical members are steel, but all the horizontal and diagonal structural members are made of dielectric material. In addition, the tower is angled five degrees to deflect any stray reflections away from the AUT. We refurbished and re-installed existing S-A components, including a Model 5671 mounting fixture, 56161 polarization positioner, and the antenna carriage and drive winch mechanisms from a Model 59110 18-foot source tower.

   

Ground reflection range. For the 200-foot range, we refurbished Motorola's S-A Model 51150 Azimuth positioner and designed and built a 20-foot vertical probe positioner. The vertical probe positioner supports antennas up to 100 lbs. and has a range of motion from one to nineteen feet above the ground plane. It is fitted with safety limit switches and a remote control unit to permit operation from inside the control building.

  Motorola 200-foot ground reflection range & spherical nearfield scanner Probe Antenna Sacnner, 200-foot ground reflection range
 

The 200-foot ground reflection range, viewed from the 300-foot range's source tower, and a closeup (right) of the probe antenna positioner mounted on the corner of the antena range control building. When making measurements on the ground reflection range, the spherical nearfield scanner is stowed below grade and under the yellow cover panels.

Spherical nearfield scanner. The Howland Model 9409 spherical nearfield scanner is built around the ground reflection range’s vehicle turntable, and retracts below ground level to prevent inference when the range is used in its ground reflection mode. To minimize reflections, the scanner is built almost entirely of dielectric materials. The fiberglass truss masts support a lightweight probe boom made of helical wound fiberglass pipe. Each mast uses a Howland elevation positioner with heavy duty worm gear drive and open-loop stepper motor. Howland also developed a positioner control system built around off-the-shelf stepper motor controllers. The scanner operates over the 100 MHz – 2 GHz frequency range, has a positioning accuracy of ±0.1 degree, and can operate safely in 40 mph winds.

Spherical Nearfield Scanner, Motorola's Antenna Range Complex