Building a Complete RF and EMC Shielded Test System
Building a shielded test system involves more than specifying a chamber and ordering equipment from a catalogue. A complete, functional system is the sum of many parts, and the performance of the whole depends on each component being correctly specified and compatible with the others. NTD Shielding has been supplying, designing and integrating RF and EMC shielded test environments for decades, and this page brings together the key elements of a complete system in one place.
Whether you are setting up a new test facility, upgrading an existing one, or sourcing individual components to fill a gap in your current setup, the sections below cover what you need and where to find it.
The Shielded Chamber
The chamber is the foundation of any RF or EMC shielded test system. It provides the controlled electromagnetic environment that makes repeatable, reliable testing possible. For emissions testing, the chamber must attenuate external signals to prevent false readings. For immunity testing, it must contain the test fields and protect personnel and equipment outside.
NTD Shielding designs and manufactures EMC test chambers from the ground up, including full anechoic and semi-anechoic configurations, as well as screened rooms and reverberation chambers for specific applications. Chamber size, shielding effectiveness, and frequency range all need to match your test requirements before anything else is specified.
RF Absorber and Ferrite Tile Linings
A shielded enclosure alone does not make an anechoic chamber. To achieve the free-space conditions required for radiated emissions and immunity testing, the internal surfaces of the chamber need to be lined with RF absorptive material. Ferrite tiles are used at lower frequencies, typically below 1 GHz, while hybrid absorbers extend performance up through microwave frequencies.
Selecting the right absorber specification depends on the frequency range in use, the chamber geometry, and the standard being tested to. NTD supplies ferrite tiles and absorber linings and can advise on the correct combination for your chamber dimensions and test requirements.
EMI Power Filters
One of the more commonly underspecified elements of a test system, the mains power filter serves a critical function. It prevents conducted interference from entering or leaving the shielded chamber via the power supply lines, which would undermine the isolation the chamber provides. For a chamber to achieve its rated shielding effectiveness, the power filter must be matched to the chamber’s specification.
NTD supplies EMI power filters suitable for a range of chamber installations, from single-phase filtered inlets to multi-phase systems for larger facilities.
Immunity Test Equipment
Conducted and radiated immunity testing requires a range of signal generation and injection equipment. The specific instruments depend on which test standards apply, but a well-equipped immunity test system typically includes ESD simulators, burst and surge generators, and a multifunctional immunity test system capable of running several test types from a single platform.
NTD supplies ESD guns and electrostatic discharge simulators for IEC 61000-4-2 testing, and the 3C Test CCS series of compact immunity test systems, which cover burst, surge, ring wave, dip and interruption, and several other IEC 61000-4 test functions in a single chassis.
View ESD Guns and Discharge Simulators | View 3C Test CCS Immunity Test Systems
RF Amplifiers
Radiated immunity testing to standards such as IEC 61000-4-3 requires high field strengths across a wide frequency range. Generating those field levels reliably demands power amplifiers with sufficient output, appropriate frequency coverage, and stable performance over extended test periods. Amplifier selection depends on the field levels required, the antenna being driven, and whether the test is conducted in a shielded room or an open-area test site.
NTD Shielding is the UK distributor for Vectawave RF amplifiers, covering frequencies from HF through to microwave, in both solid-state and combined solid-state configurations.
Antennas and RF Components
The antenna is the interface between the test system and the equipment under test. For radiated emissions testing, a calibrated receive antenna is needed across the frequency range of interest. For radiated immunity, a transmit antenna with appropriate gain and pattern characteristics is required to achieve the specified field levels.
NTD supplies antennas and RF components from Impulse Technologies and Schwarzbeck Mess-Elektronik, covering biconical, log-periodic, horn and hybrid antenna types across a wide frequency range. Phase shifters, attenuators and other passive RF components for signal path management are also available.
View Impulse Technologies RF Components | View Schwarzbeck Antennas
Masts and Turntables
Accurate radiated measurements require the antenna and the equipment under test to be positioned precisely and consistently. Antenna masts provide controlled height scanning over the required range, while turntables rotate the equipment under test to find the angle of maximum emission or the worst-case immunity orientation.
NTD supplies masts and turntables from INNCO Systems, a specialist manufacturer with a range covering the requirements of both semi-anechoic chamber testing and open-area test sites.
EMI Receivers and Test Analysers
A calibrated EMI receiver is the measurement instrument at the heart of a radiated or conducted emissions test. Unlike a general-purpose spectrum analyser, an EMI receiver is built to the CISPR 16-1-1 specification and provides the quasi-peak, average and peak detector functions required for compliance testing. For pre-compliance work, a spectrum analyser with appropriate software may be sufficient, but formal compliance measurements require a CISPR-compliant receiver.
NTD supplies the Rohde & Schwarz ESRP7, a combined EMI test receiver and spectrum analyser covering 10 Hz to 7 GHz, which is well-suited to both pre-compliance and full compliance test environments.
EMC Test Software
Bringing the measurement instruments together into a functioning test system requires software that can control the hardware, manage the test sequence, collect and process the data, and produce compliant test reports. Choosing the right software platform at the outset is important — retrofitting it later, once the rest of the system is installed, is rarely straightforward.
NEXIO EMC test software from Micronix is a flexible platform supporting emissions, immunity and field uniformity testing, with drivers for a wide range of receivers, analysers, amplifiers and switching hardware. NTD supplies and supports NEXIO in the UK.
RF Shielded Test Enclosures
Not every shielded test requirement calls for a full walk-in chamber. For bench-level testing of smaller devices, modules and subassemblies, a shielded test enclosure provides the isolation needed without the footprint or cost of a full installation. These are also widely used for over-the-air testing of wireless devices, where a compact, high-attenuation enclosure allows repeatable testing in an ordinary lab environment.
NTD’s own NTD X100 range of RF shielded test boxes provides high attenuation across a wide frequency range, with a range of access and connector options to suit different test configurations.
System Design and Consultancy
Specifying a shielded test system correctly from the start avoids the cost and disruption of modifications later. The interactions between components, particularly chamber shielding effectiveness, filter specifications, and absorber performance, mean that a system is only as strong as its weakest element. NTD can advise on system specification, whether you are starting from a blank floor plan or reviewing an existing facility.
EMC Consultancy and Expert Advice | Testing and Calibration Services