OverviewComb Generator

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Supplier of Instrumentation & Equipment for EMI / EMC Testing Since 1989

What is EMI EMC Testing?

Electromagnetic Compatibility, or EMC, is defined as the ability of a product to operate within its intended electromagnetic environment; to accept interference from other devices within its environment, including interference that may cause undesired operation, and to not interfere with the operation of other devices.

Limits for emission levels are set by the various worldwide regulatory agencies. EMC testing can be divided into two areas; electromagnetic immunity testing – (the ability of a product to withstand external electromagnetic disturbances and emissions testing.

Com-Power Corporation specializes in the field of Electromagnetic Compatibility commonly referred to as EMC. We make variety of products related to noise; our EMC equipment will help you find, measure and suppress noise in your products. Out test equipment can be used to meet the regulatory requirements for EMC or just to make your products work better.

Com-Power’s line of EMI/EMC test equipment can be used for compliance or pre-compliance emissions and immunity testing from DC to 40 GHz to meet the various National and International EMC regulations/standards. We are the leading producer of reference EMI noise sources (comb generators) for validating EMI test sites up to 18 GHz. Our patented near-field probe sets have helped countless engineers around the world to find solutions for EMI noise problems in their products.

It is our goal to provide the finest products as well as the best support to our customers. We continually improve our products and design new products to help our customers meet their goal. We believe our customer’s success will lead to ours.

EMC Comb Generator



EMC labs calibrate their radiated emissions test sites, instrumentation and accessories at least once a year. The calibration procedures are elaborate and time consuming and may require other specialized test equipment and in some cases use of outside services. However, calibration does not prevent equipment malfunction in between calibration period such as damaged receivers,, broken cables, poor connections, bad antenna, etc. To improve the measurement accuracy or reliability, you have to check these items at closer intervals. It could be a daily procedure. Performing a full calibration each time is expensive and daily is not practical. The problems with equipment may not be noticed during EMC testing and faulty data may result. A quick test using a Comb Generator can avoid this situation. Monitoring a few frequencies regularly on the Comb Generator’s broadband radiated output can verify the entire setup quickly and efficiently. Any potential problems with the test setup can be detected before it causes erroneous results. In addition, Comb Generator data gathered over a period of time will provide information about the measurement consistency of the site. This will turn increases overall measurement confidence of the test site.

The Comb Generator can also be utilized to compare sites. Sometime, questions arise when EUT emissions test data is not consistent between two test sites. Comb Generator can be used to compare the sites. Gathering the comparison data is valuable for mitigate these issues and to identify the problem. EMC labs with multiple sites can utilize the Comb Generator as a standard to compare all the sites, increasing overall confidence in the measurement capability of the entire test facility.

The Comb Generator is self contained, small and portable. Unlike other signal sources it has no interconnecting cables that might interfere with the radiated output. The Comb Generator is powered by internal rechargeable batteries. When the unit is turned on all the frequency harmonics of specified step size is available up to maximum range of operation. The Comb Generator uses extremely stable components to minimize output variations. The output is uniformly radiated in all directions using monopole antennas.

Although Comb Generators were designed for EMC site testing, it can be a signal source for applications such as testing cables, filters and shielding effectiveness.


The CGC series Comb Generator was specifically designed to test installed Line Impedance Stabilization Networks (LISNs). LISNs are used for EMC conducted emissions testing according to FCC Part 15, CISPR, and EN requirements. The Comb Generator output is connected to the LISN EUT power port and measurements are taken similar to an EUT. For convenience, the CGC series Comb Generators have 3 prong standard US plug for LISNs with matching EUT power socket. By using the Comb Generator the test engineer can quickly identify any problems with the conducted setup before making any measurements with an EUT. the Application Note AN-104 provides more details on the Comb Generator.

Comb Generators for Testing Radiated Emissions Sites

Model STEP SIZE Frequency
CGO-501 1 Mhz 1 – 1000 Mhz
CGO-505 5 Mhz 5 – 1500 Mhz
CG-515 1 & 5 Mhz 1 – 1500 Mhz
CGO-515 1 & 5 Mhz 1 – 1500 Mhz
CGO-520 20 Mhz 20 – 4500 Mhz
CGO-5100B 100 Mhz 1 – 18 Ghz
CGO-51000 1000 Mhz 1 – 34 Ghz
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Comb Generators for Testing Setups with Line Impedance Stabilization Networks (LISNs)

CGC-255E 50 & 250 khz 50 khz – 400 Mhz
CGC-510E 100 & 500 khz 100 khz – 400 Mhz

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