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This new family of baluns for EMP, lightning and EMC instrumentation replace the older EG&G baluns. They are much improved in high frequency performance, bandpass ripple and termination of the undersired signal mode. The older versions will still be available on special requests.

The differential-mode balun is used to transform the balanced 100-ohm signal from a differential (free-space) field sensor to an unbalanced 50-ohm signal for input to a 50-ohm coaxial cable, oscilloscope, or isolated data link. It changes the input signal of Vo across 100-ohms to an output signal of Vo/2 across 50-ohms; half of the input power is dissipated in the balun so that the insertion loss is 3dB. When the balun is tested by driving only one input (with the other input terminated in 50-ohms) only one-fourth of the input power is delivered to the output and the apparent insertion loss is 6 dB.

The common-mode balun is the same as the DMB except that the inputs are wired oppositely to attenuate the differential input and pass the common-mode signal. This instrument is utilized to measure the actual common-mode signal from a field sensor to determine its effect on the differential signal measured subsequently with the DMB.

Two versions are available: The model DMB-3 is essentially a direct replacement for the DMB-1 (20 kHz-1 GHz). It is normally supplied with locking GR connector hardware for direct connection with the larger free-field sensors, a TCC twinaxial input connector, and a standard GR874 output connector (dual inputs, single output). SMA connectors or type “N” connectors may be requested.

The DMB-4 is a higher frequency model (200 kHz-3 GHz) for use with the small, high-frequency free-field sensors with SMA connectors. GR or type “N” connectors may be ordered on special requests. A reduction in performance specifications may occur with these non-standard connectors.