Patent ID: 7388379

Claim:
A method for processing an electromagnetic wave, comprising: (a) receiving in a borehole, via a receiver loop antenna, an electromagnetic wave having a plurality of interrogation frequency components; (b) simultaneously selecting the plurality of interrogation frequency components of the electromagnetic wave via a tuning network, the tuning network being electrically connected in series with the receiver loop antenna such that (i) an electrical current in the loop antenna equals an electrical current in the tuning network and (ii) the tuning network provides for simultaneous series-resonant tuning of the loop antenna at each of the plurality of interrogation frequency components; (c) generating a pick-up signal that is representative of relative magnitude and phase of each of the plurality of interrogation frequency components, the pick-up signal in the form of a voltage differential across first and second nodes; and (d) minimizing secondary electromagnetic radiation from the loop antenna at at least one of the plurality interrogation frequency components by providing a sufficiently high load impedance to the first and second nodes, wherein the load impedance is provided by a preamplifier circuit and a transformer, a primary winding or the transformer electrically connected in series with the loop antenna and the tuning network, the preamplifier circuit electrically connected to a secondary winding of the transformer.