Pre-amplifier and mixer circuitry for a locator antenna

摘要

A pre-amplifier circuit for connection to an antenna of a human-portable locator includes a differential amplifier/mixer pair and means for allowing a common-mode “phantom” signal to modulate a transfer function of the differential amplifier/mixer pair. The common-mode phantom signal modulates the transfer function of the differential pre-amplifier “onboard” the antenna without the usual requirement for onboard power supply and signal oscillator. This technique uses the same electronic components to provide both pre-amplification and mixing functions, thereby improving circuit performance-to-cost ratio, reducing mixer power consumption, situating the necessary signal oscillator remotely from the mixer, and greatly improving the available system bandwidth by limiting spectral transmission demands to the mixed signal bandwidth alone.

主权项

1. A portable locator comprising;
a housing assembly; a processing and user interface sub-system disposed on or within the housing assembly for providing information associated with a buried object; an antenna; and an antenna interface circuit coupled to the antenna and processing and user interface subsystem including a switchable combination preamplifier and mixer circuit configured to be selectably switchable between preamplification and mixing responsive to a remotely generated phantom signal; wherein the antenna comprises a conductive bobbin and wherein the conductive bobbin comprises an element of a nested omnidirectional antenna array.