Industry standards require Over-The-Air (OTA) characterization of cell phones (handsets) before they are used in the US. OTA measurements require measuring the radiation characteristics of the handset in a spherical coordinate system. OTA test systems must contain a two axis positioning system that allows the orientation of the handset to be varied in the phi and theta angles of a spherical coordinate system.

The Howland Company wireless test labs were developed in collaboration with Motorola engineering. The first priority was to design products that would set the industry standard for accurate measurements. With this goal in mind, it became apparent that how one mounts the handset to the positioning system is critical if the measurement uncertainty is to be minimized. The classical approach would have been to mount the handset on a two-axis positioner. However, if this is done, then the positioner structure, even if it is plastic, perturbs the electromagnetic field and dramatically increases the measurement uncertainty and creates 'gravity vector' problems which contribute additional measurement uncertainty.

The Howland Company's wireless test labs employ a distributed axis positioning system. The handset sits on a low dielectric foam block which rotates in phi--this arrangement eliminates gravity vector problems. The measurement antenna is mounted to a low dielectric mast which moves in theta. As a result, the measure-ment uncertainty contribution due to quiet zone ripple of The Howland Company wireless test labs is the lowest in the industry, typically less than 0.28dB at 95% confidence.

There are three models of wireless test labs:

The Model 3100 is designed to meet the CTIA requirements in the smallest possible space.

The Model 4100 is designed for mobile video applications and operates down to 400MHz.

The Model 5100 offers the ultimate in accuracy and supports full body phantom tests.

Model 3100 Wireless Test Lab

The Model 3100 is the smallest chamber available on the market that meets the certification requirements of the CTIA Test Plan for Mobile Station Over the Air Performance. The shielded chamber is a 10 foot (3 meter) cube. The Model 3100 can be installed in rooms with a 10 foot (3 meter) ceiling height.

In spite of its small size, the quality of the electro-magnetic field is excellent and far exceeds the performance of much larger chambers. The secret to the Model 3100's high quality electromagnetic field is its distributed axis positioning system. This allows the handset to be supported on a block of low density styrofoam, avoiding 'gravity vector' issues, and minimizes the interaction of the test device and the positioning equipment. Typical ripple in the quiet zone is less than +/-0.5dB and the measurement uncertainty contribution at 95% confidence is less than 0.28dB.

The software for the Model 3100 was developed by Motorola and is in use in their design centers around the world. This software supports several different instrumentation configurations.

Model 3100 Specifications

Model 3100 ICD      Model 3100 Data Sheet

Model 4100 Wireless Test Lab

The Model 4100 Wireless Test Lab is specifically designed for mobile video applications, both terrestrial and satellite.

It is designed with thicker absorber to allow it to operate down to 400MHz and a longer range length to keep the measurement antenna out of the reactive near-field of the equipment under test.

Model 4100 Specifications

Model 4100 ICD      Model 4100 Data Sheet

Model 5100 Wireless Test Lab

The Model 5100 was designed for full body phantom testing. More and more users are connecting to the handset with a Bluetooth link. This means that the handset may be operating from a pocket, belt clip or other location on the body. The Model 5100 allows handset designers to evaluate the handset performance at different points on the body.

Model 5100 Specifications

Model 5100 ICD

Model 5100 Brochure