Design and calibration of the NBS isotropic electric-field monitor (EFM-5), 0.2 to 1000 MHz

Possible designs for electric-field-strength probes for millimeter waves

“…The resistive profile which was used for the dipoles was This resistive tapering was achieved by tapering the width of the resistive strips that constitute the dipole arms, as shown in figure 1. The tapering required to eliminate reflected currents depends on the frequency, and therefore eq (1) will not be the optimal tapering for frequencies above 18…”

“…For present purposes it suffices to consider the two most successful and popular probe designs relevant to frequencies above 1 GHz.…”

“…Thus, for example, the EFM-5 [1], which uses 5 -cm dipoles (resonant frequency about 3 GHz) , can only be used up to 1 GHz before its response becomes frequency dependent.…”

“…The basic configuration used at NBS in developing the isotropic electric-field probe [1], and used in subsequent NBS and commercial probes, is an electrically short dipole with a diode detector (typically a beam-lead Schottky diode), connected to a metering unit by a high-resistance filter line.…”

“…Transfer standard probes of this sort which the National Bureau of Standards (NBS) has developed in the past include the EFM-5 [1] and the 8-mm resistively tapered dipole [2],…”