- comb generators are useful for testing radiated noise measurements and shielding effectiveness
Here are two new TekBox TBCGx Comb Generators for EMC testing:
The TBCG1 is a radiating comb generator with an internal dipole antenna and a base frequency of 100MHz. It radiates a comb spectrum that is characterized up to 6GHz. The comb generator is intended as a quick reference for testing radiated noise measurements in anechoic chambers, TEM/GTEM cells, shielded chambers, or to gauge the effectiveness of cable shielding and other shielding materials. With its built-in dipole antenna the TBCG1 can be used in three orientations to emit vertically- or horizontally-polarized signals. It is a compact and portable device, powered by a 9V alkaline cell. Being self-contained and battery-powered, there are no cables to disrupt the emitted field.
The TBCG2 is a versatile, passive comb generator/frequency multiplier which takes a square-wave input and creates a wide spectrum of comb frequencies. Based on a step-recovery diode design, this comb signal generator is optimized for an overall flat spectrum with an output frequency range from 1MHz to 2.5GHz. The recommended drive power is between +10 dBm and +20 dBm with an input frequency of 1MHz to 350MHz. The TBCG2’scapability to work with such low drive frequencies makes it also suitable for the measurement of cable resonances. Cables on a product can themselves act as an antenna, causing radiated emissions and possible compliance test failures. They can resonate at their half-wave frequency and magnify any harmonic currents in the cable shield near that resonance. The resonant frequency of cables and wires in a product or system can be characterized by injecting harmonic energy from a comb generator into the cable and observing the resultant resonances on a spectrum analyzer; a primary peak will show where the harmonic content is resonant.
Every EMC test engineer should own a harmonic comb generator that produces a simultaneous set of harmonically related CW signals whose spacing is based on a fundamental oscillator frequency. The harmonic amplitudes produced are consistent and can be used as a frequency and amplitude calibrator, insuring, for example, that a semi-anechoic test chamber is reading correctly from day to day. Simply place the TBCG1 generator on a turntable and measure specific harmonics each day and record the trend data. Loose connectors or bad cables can be detected by comparing the current readings with past data. This will fulfill the requirement for “equipment verification testing” as specified in ISO 17025.
TBCG1 Radiating Comb Generator Specifications:
- Base frequency: 100MHz
- Comb spectrum: 30MHz - 6GHz
- Tolerance: +/- 2.5dB
- Power supply: 9V alkaline battery
- Current consumption: 175mA
- Dimensions: 3.2” x 2.4” x 1.1”
- Weight (incl. 9V battery): 3oz
TBCG2 Comb Generator Specifications:
- Input Power: +10 dBm to +20 dBm; 25 dBm max.
- Input Frequency: 1MHz to 350MHz
- Comb spectrum: 1MHz - 2.5GHz
- Input connector: N female
- Output connector: N male
- Dimensions: 3.2” x 1.1” x 1.1”
- Weight: 3.5oz
Manufactured by Singapore-based Tekbox Digital Solutions, the TekBox TBCGx Comb Generators are available now from their authorized North American distributor Saelig Company, Inc. Fairport, NY.