JEM Engineering's TATF Chamber

JEM’s TATF Chamber Capabilities

JEM’s Tapered Antenna Test Facility (TATF) Chamber provides powerful validation capabilities over a wide frequency range, allowing us to test antennas and antenna systems for a variety of applications. Using these tools, we are able to measure radiation patterns, antenna gain (peak, average, max linear, min linear, H and V) and axial ratio from 80 MHz to 40 GHz.

Measurement accuracy is critical, and our TATF chamber offers accuracy of peak gain measurements ± 1.0 dB from 80 to 400 MHz, ± 0.7 dB from 400 MHz to 1 GHz, and ± 0.5 dB from 1 GHz to 18 GHz. The data analysis and reduction software supports a wide range of outputs, including radiation patterns and swept gain. We produce ASCII data files compatible with third party analysis tools such as MATLAB®, MathCAD® or EXCEL®

TATF Physical Setup

TATF Chamber Physical Diagram

Rotator Plate Bolt Pattern
tapered antenna rf test chamber equipment setup 2D or 3D pattern

Plate can support up to 3,000lbs.
Testing apparatus must be 50” or less from the center of the Plate to the outside edge in order to clear the backwall during rotation.

Antenna Quiet Zone by Frequency
tapered antenna rf test chamber equipment setup 2D or 3D pattern

All antennas under test must fit inside the Antenna Quiet Zone for the duration of the test.  Outside of the Quiet Zone, measurement accuracy dramatically reduces.

Source Antenna Coverage

The log scale above shows the coverage of each of our standard source antennas. Additionally, JEM uses a variety of source antennas to minimize the number of setups required per test, thereby reducing the time and expense required to get the data you need.


Our existing structures allow us to fixture multiple antennas during the allotted test time.  If the weight of the antenna under test is off-center by more than 36”, or if the antenna requires a specific configuration, a custom fixture may be necessary. Customers have the option to design, as well as provide their own fixtures. Also, JEM may design and build a custom fixture for a separate fee. Please send us a request for the drawings or the dxf artwork files for the mounting patterns, and we will respond as promptly as possible.

Frequently Asked Questions


  • What frequencies can be measured in the Tapered Chamber?

    The operating frequencies are 80MHz to 40GHz.

  • What type of equipment is used?

    The heart of the Tapered Chamber is our 2-port Agilent N5230A network analyzer (PNA) which spans 10 MHz-40 GHz; we use several RF amplifiers at the source end to boost the signal depending on the frequencies being tested. The azimuth, roll, and source positioners use stepper motors controlled by the software via a National Instruments nuDrive.

  • What patterns/cuts can the Tapered Chamber measure?

    We can measure “boresight” (main beam or just one sweep of the PNA with no AUT movement); 3 principle planes or 1D patterns using only our azimuth positioner in an Azimuth / Horizon / Phi cut, or by affixing the AUT sideways, Elevation / Theta / Great Circle cuts; and full 4-pi steradians using our roll fixture to perform a “roll over azimuth” measurement. Patterns are also not limited to 360 degrees, ex. -90 to +90 or 180 degree cut, -45 to +45 or 90 degree cut, etc.

  • What pattern resolutions, in degrees, are possible in the Tapered Chamber?

    Our Tapered Chamber software is flexible and can accommodate any resolution down to .1 degree. However, the greater the resolution, the longer the test will take.

  • How long does a typical test take?

    Test times depend on the number of frequency points taken, the number of angular steps measured, and the amount of noise correction applied. 1D patterns can be as short as 90 seconds or as long as an hour depending on the settings. 3D spherical test times can change drastically with the settings, namely angular steps chosen. (ex. a full 5 degree spherical test with 51 points and no noise correction takes about 2 hours). Spherical tests can take as long as a day with noise correction and more angular points.

  • What is the highest gain that can be measured?

    The max power at the input port of the PNA is +30 dBm; however we can add a pad in line to allow gain much higher (as much as +110 dBm).

  • My antenna has an amplifier and/or attenuator, can you still measure it?

    The gain can be offset to account for amplification or attenuation. We can even use a frequency swept measurement to offset the gain data and derive the antenna gain.

  • I have an Active device. Can it be measured?

    Active measurements cannot currently be automated in the Tapered Chamber. We are looking into upgrading our chamber software to read a power meter.

  • I have my own receiver. Can it be supported?

    We can use the chamber and positioning equipment in a “quiet room” fashion. We can supply a CW signal and spin the azimuth in an automated way (ex. Step through frequencies, angles or both, or by manually clicking through each step).


Handling the Data:

  • Can the output files be read by my processing software?

    All of the data exported is in standard ASCII text format and can be read by Excel, MatLab, and other standard software packages.

  • Can I look at specific data cuts and frequencies during the measurement session?

    It is your time to spend as you want. We can process the previous measurements’ data while a measurement is taking place and can plot patterns and compare data. All it costs is the time taken to process the data. Most customers process the data for specific pattern cuts later to save time for sample measurements.

  • What data output is available?

    Data is saved as an ASCII file. Patterns can be exported by frequency.

  • How will I get my data?

    Data can be burned to a CD, DVD, or copied to a memory stick. We also have an FTP site that you can download your data from. You will be emailed a link for the site, and only you will be able to access your data from the FTP site.

  • How long will the data be on your system?

    We will keep your data for at least 1 month unless you tell us to delete it.

  • We have sight sensitive samples. Can these be accommodated?

    We have run sight sensitive samples in the range. We have a camera in the range that can be disabled. Once we have run you through the antenna mounting procedure, you can mount your own samples. We do not need to see your antennas to measure them and process the information.

  • Can JEM measure classified antennas?

    Whether or not we can measure and process the data from a classified antenna is defined by your particular program, and can only be determined by your Security Officer. The range is behind an unlocked door in our main building. The measurement frequency band can be padded with extra frequencies to hide specific points. We could save your data exclusively to external media if needed, and the computer can be unplugged from the JEM network.