Tx-Rx Communication Delay Compensation by Using Negative Group Delay Circuits

This article deals with an experimental study on a novel method of communication delay compensation related to wireless and wired microwave systems. The developed method uses basically the bandpass (BP) negative group delay (NGD) circuit. The delay compensation principle is investigated via a scenario of experimental test setup, including transmitter (Tx) and receiver (Rx) antennas utilized for free-space link. To reduce the communication delay, the BP-NGD circuit was cascaded in upstream of Tx port or in downstream of Rx port of TxRx system. As a part of delay compensation demonstrator, three microstrip BP-NGD circuits specified by the NGD value and center frequency equal to −6 ns at 2.432 GHz, −2.4 ns at 4.965 GHz, and −3.5 ns at 2.995 GHz are considered. The feasibility of NGD compensation method is verified by both simulations and measurements of TxRx communication demonstrators in the L and S bands, including the wireless free-space and wired links. The BP-NGD circuits under study were connected in cascade with 1-m distant TxRx Vivaldi antennas operating from 2 to 6 GHz, which are set up in an electromagnetic radiation measurement semianechoic room. The experimental results show that the TxRx communication group delay (GD) reduction is up to 58.9% around gigahertz operating frequencies. In the future, the NGD compensation method can be potentially exploited for delay correction and signal synchronization of wired and wireless multiband communication systems.