Novel Dual-Mode Retrodirective Array Using Synthesized Microstrip Lines

Abstract

In this paper, an innovative architecture for realizing a dual-mode retrodirective array (RDA) is proposed and experimentally validated. The new design functions as a reflection-type RDA in one frequency band and features the characteristics of a Van Atta array in the other band. A unique 50-synthesized microstrip line is applied to fulfill the core building blocks of this RDA, i.e., the dual-mode quadrature hybrids and crossovers. Both couplers show equivalent responses to their conventional counterparts in the low-frequency band, but enable direct-thru transmission properties in the high band. To validate this innovative architecture, a four-element dual-mode RDA is fabricated and experimentally verified. The measured bistatic radiation patterns provide supportive evidence to the dual-band self-steering capability of the proposed array. The circuit topologies, design approaches, system considerations, and simulated and measured results are investigated in detail throughout this paper. Suggestions to improve the system performance are discussed as well.Index Terms-Crossover, dual mode, quadrature hybrid, retrodirective array (RDA), synthesized microstrip line.

Maxwell Fisheye Lens Based Retrodirective Array

“…3), phase conjugation analogous to Van Atta phase aligned transmission lines (e.g. 24,25 ) is possible without the requirement of crossovers. Next, we show how to create a retrodirective reflector using the fisheye lens.…”

Ultracompact Retrodirective Antenna Arrays With Superdirective Radiation Patterns

“…More detailed discussion on the realization of the PC circuitry can be found in review papers [16], [30]. Impedance matching between the antenna and PC circuitry is specific for each PC unit realization [16], [30], [31] but in general it is based on the conjugate matching technique [32]. It should also be noted that often the retrodirected signal has a small frequency offset with respect to the frequency of the incident wave carrier [16], [30].…”

“…It should be noted that the process of evanescent-topropagating spectrum conversion and the reverse process of the propagating-to-evanescent field conversion leading to the extraction of the radiation system subwavelength features has been studied theoretically and experimentally in [20], [31]- [34]. It should be noted that in this paper we establish, for the first time, a complete EM picture of the retrodirected near field formation in ultra-compact antenna arrays using electrically small elements at high radiation efficiency which is crucial for free-space far-field wireless applications.…”