Wireless Test Labs

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 (Φ); this arrangement eliminates gravity vector problems. The measurement antenna is mounted to a low dielectric mast which moves in theta (θ). As a result, the measurement 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.

 

Model 3500 Wireless Test Lab--Phantom Head with mobile phone
 --THC Photo by Jim Howland

 

We offer five standard models of wireless test lab:

 

This Overview Table summarizes the characteristics and dimensions of each model. (PDF available here.)

The Model 2100A offers fast OTA and pattern measurements for production and development environments in the smallest possible space.

The Model 3100 meets the requirements of the CTIA OTA Test Plan in the smallest possible space.

The Model 3500 meets the expanded requirements of Version 3.0 of the CTIA OTA Test Plan, while offering improved ease of operation and measurement capability.

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

The Model 4800 offers the ultimate in accuracy and supports full body phantom tests.

Howland Model 4100 Wireless Test Lab exterior
     
Wireless Test Lab Models Overview

Comparison chart of Howland Wireless Test Lab models. PDF download available.

Additional Information:

Download PDF Wireless Test Labs Overview (PDF version of the chart above)

Download PDF "Using Spherical Near-Field Transforms to Determine the Effects of Range Length
on the Measurement of Total Radiated Power
" AMTA Symposium Technical Paper

Download PDF  "Testing Large Wireless Devices in Small Anechoic Chambers" AMTA Symposium Technical Paper  

Download PDF "Wireless Test Lab Design Considerations"

Download PDF "The Effect of Range Length on the Measurement of TRP" AMTA Symposium Technical Paper

Download PDF "Uncertainties in TRP Measurements Due to Finite Range Lengths"AMTA Symposium Technical Paper

Download PDF "Range Length Requirements for Notebook Computers" AMTA Symposium Technical Paper

Download PDF "A Small Chamber for Wireless Over-the-Air Measurements" AMTA Symposium Technical Paper

Download PDF "A Comparison of Methods for Evaluating the
Test Zone Performance of Anechoic Chambers
Designed for Testing Wireless Devices"
AMTA Symposium Technical Paper

Download PDF "Broadband Gain Standards for Wireless Measurements" AMTA Symposium Technical Paper

Download PDF "Novel Spherical Near-Field Antenna Measurement Techniques" AMTA Symposium Technical Paper