A circuit includes an antenna circuit including a number of capacitors and an inductor. The antenna circuit is configured to transmit an output signal upon receiving an input transmit signal. A first control block is configured to transmit an enabling signal upon detecting a presence of a supply voltage at a feeding terminal of the actively transmitting tag in response to the actively transmitting tag being inserted into a host device. A VCO is configured to generate the input transmit signal with the frequency of the interrogator carrier signal upon receiving the enabling signal from the first control block and upon receiving the control voltage from the memory. A second control block is configured to enable a subset of the plurality of capacitors of the antenna circuit upon receiving the enabling signal from the first control block.