GTEM Cell Basics: Construction, Applications, and Manufacturers

A GTEM Cell is a widely used electromagnetic testing environment designed for EMC (Electromagnetic Compatibility) and RF (Radio Frequency) measurements. It provides a controlled and repeatable testing setup for characterizing electronic devices. This page covers GTEM Cell (Gigahertz Transverse ElectroMagnetic cell) basics. It mentions GTEM Cell benefits, construction, applications, and popular GTEM cell manufacturers.

Introduction

There are different types of TEM (Transverse ElectroMagnetic) cells viz. TEM, GTEM, WTEM, and EUROTEM. There are differences in these types of cells with respect to their construction, electric field, magnetic field, electric potential, FEM techniques, etc. In this page, we will focus on the GTEM cell.

What is GTEM Cell?

• GTEM stands for Gigahertz Transverse ElectroMagnetic.
• GTEM cell is used as an EMC test chamber for radiated EMC (Electro-Magnetic Compatibility) testing.
• It is a small enclosure similar to an anechoic chamber. It is made using conductive metal having a rectangular pyramid shape. EM absorber material is placed on its base, whereas nothing is mounted on its sides, which act as a waveguide. It is placed on the ground on one of its sides, as shown in Figure 1 (side view). A small part of the side wall is fixed with an access door. This access can be used for EUT placement, test connections with outside equipment, as well as for maintenance of the GTEM cell.
• As shown in the figure, a septum (i.e., stripline conductor) is used to connect the input or output port (at the apex of the pyramid) with the RF load of 50Ω value (at the base of the pyramid). The septum is called the center conductor.

• As shown in the figure, the EUT (Equipment Under Test) is placed between the septum and the chassis.
• As shown in the GTEM cell test setup, an RF signal generator and power amplifier are used for radiated immunity tests.
• A spectrum analyzer is used for radiated emission tests.

GTEM cells are usually available for frequencies up to 20 GHz. It provides shielding better than about 60 to 110 dB as per the frequency of operation. N-type connectors are provided for outside connectivity with RF equipment. High-quality absorbers (350 mm) are generally used for its construction. GTEM cells are designed, developed, and optimized for EMI (ElectroMagnetic Interference) and EMC testing purposes.

GTEM Cell Manufacturers

The following table mentions popular manufacturers of GTEM Cells (Gigahertz Transverse ElectroMagnetic cell).

Benefits of GTEM Cell

Following are some of the advantages of GTEM Cell.

1. Wide Frequency Range : Supports testing from DC to GHz frequencies, making it suitable for a broad range of RF and EMC applications.
2. Compact and Shielded Environment : Unlike large anechoic chambers, GTEM cells provide a compact and cost-effective setup while ensuring minimal external interference.
3. Faster Testing Process : Enables quicker radiated emission and immunity testing compared to open area test sites, reducing testing time and increasing efficiency.
4. Cost-Effective Solution : Eliminates the need for large, expensive chambers and reduces operational costs while maintaining high testing accuracy.
5. Versatile Applications : Used for pre-compliance EMC testing, antenna characterization, RF exposure analysis, and wireless device evaluations.
6. Controlled and Repeatable Measurements : Provides a uniform electromagnetic field, ensuring consistent and reproducible results for device performance verification.
7. Safer Testing Environment : Fully enclosed design minimizes radiated emissions leakage, ensuring a safe working environment for engineers and researchers.

Conclusion

A GTEM Cell is an essential tool for RF and EMC testing, offering a compact, cost effective and efficient alternative to traditional anechoic chambers. Its broad frequency support, controlled test environment and high measurement repeatability make it invaluable for pre-compliance testing, product development and regulatory compliance verification. As the demand for wireless communication and EMC standards increases, GTEM cells continue to be a critical asset for engineers in designing and validating electronic devices.