Preamplifiers

Com-Power high gain broadband RF preamplifiers are used to amplify weak electrical signals captured by antennas and near field probes during electromagnetic interference testing. Most EMC testing on DUT (device under test) are performed at 1-to-10-meter distance in an open area test site (OATs) or anechoic chamber. As the test distance increases the signal can get become difficult to see above the noise floor of typical spectrum analyzer or receiver. Some of the difficulty can be alleviated by adjusting the resolution bandwidths (RBW) of the spectrum analyzer but the most common EMC standards specify the RBW setting.

A preamplifier should ideally be located as close as possible to the receiving antennas to reduce losses associated with long cables connected to it. Com-Power also offers active antennas (AHA-118A and AHA-840A) with integrated preamplifiers make it more convenient for this type of test setup. At ten-meter distance, the coaxial cables could be longer than test distance to account for some slack. This length could get even longer when the receiving antenna is on a mast which can be raised and lowered 1-4 meters to maximize the signal reception. However, preamplifier can also be placed next the receiver or spectrum analyzer if this configuration is not practical. Especially, it the receiving antenna is mounted on antenna mast (placement of preamplifier is difficult) or the measurements taken outdoors where temperature and moisture cannot be controlled. Long Coaxial cables generally have higher loss as you go up in frequencies. Having a preamplifier with high gain will definitely mitigate some of the difficulty making these measurements regardless of placement of the preamplifier. The Com-Power preamplifier are low noise, so it contributes very little to overall increase system noise floor. The PAM-118A for example has noise figure of less than 3.5 dB. This helps increase overall measurement system sensitivity without increasing the noise floor to make it easier to see the weaker signals on spectrum analyzer or receiver.

Another application for preamplifier is to amplify signal picked by a set of near field probes. This especially useful for troubleshooting and locating EMC noise on circuit level of a DUT where the signal levels can be very small in amplitude.

All Com-Power preamplifiers have a rechargeable battery so it can be used in location where a power source is not be easily accessible. The battery typically last about 8 hours. This allows a typical EMC test to be completed with minimum disruption. These battery packs have NimH cells. These batteries can handle hundreds of charging and discharging cycles before they need to be replaced.

Com-Power offer several models to cover the frequency range of 100 Hz to 40 GHz.  

A brief description of each model is given below.

PAL-010: 100 Hz to 50 MHz, 28 dB gain

PAM-103:  1 MHz to 1 GHz, 32 dB Gain

PAM-6000: 1 GHz to 6 GHz, 30 dB gain  

PAM-118A: 500 MHz to 18 GHz, 40 dB typical gain

PAM-840A: 18 GHz to 40 GHz, 40 dB typical gain

PAM-840H: 18 GHz to 40 GHz, 50 dB typical gain

Calibration

All Com-Power preamplifier are supplied with calibration traceable to the International System of Units (SI) through NIST or the recognized National Metrology Institute. Com-Power also offers ISO-17025 accredited calibration.