Schwarzbeck VPMP 9242 Vertical Passive Rod Antenna

The Vertical Passive Monopole Antenna VPMP 9242 is equipped with a 10 mm element fixture to accept several different element types, e.g. telescopic, biconical or collapsible conical elements. In order to improve the efficiency especially at frequencies below 25 MHz the VPMP 9242 comes with a broadband toroid-transformer. Since monopoles are always unsymmetrical antennas in contrast to dipoles, braid currents are existing on the coaxial feed cable.

The influence of the braid currents can be minimised using a groundplane as large as possible, acting as rf-counterpoise on the one hand and supressing the braid currents (at least at high frequencies) on the other hand. Generally the use of a groundplane will improve the reproducability. If the coaxial feed cable of VPMP is touch-sensitive, this indicates the presence of braid currents.

The following steps help to reduce the influence of unwanted braid currents: Connect the flange of VPMP with your amplifier using a short, wide and lowinductance metal strip. Use a groundplane as large as possible. Use a coaxial feed cable which is loaded with appropriate ferrites to supress the unwanted currents.

VPMP 9242 und VAMP 9240 bei 2.5 m Abstand