Design of 1.9GHz-2.6GHz Microstrip Circulator Based on Ferrite Material

Ferrite-Based Multiport Circulators With RF Co-Designed Bandpass Filtering Capabilities

“…N ON-RECIPROCAL RF components, such as isolators or circulators, are of increasing importance in emerging RF front-ends as they serve two primary roles: 1) they separate the transmitted from the received RF signals in full-duplex RF transceivers [1], [2], [3] and 2) they protect sensitive RF devices against unwanted reflections [4]. One of the main approaches to realize isolators/circulators is to incorporate ferromagnetic materials within the volume of a two-port or a three-port microwave network and achieve non-reciprocity by applying magnetic biasing [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29]. Notable demonstrations of ferrite-based devices include: 1) waveguide-type isolators/circulators [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], where a ferrite slab is integrated within a 3-D waveguide or a Y-junction; 2) stripline-based [15], [16], [17], [18], <...…”

“…One of the main approaches to realize isolators/circulators is to incorporate ferromagnetic materials within the volume of a two-port or a three-port microwave network and achieve non-reciprocity by applying magnetic biasing [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29]. Notable demonstrations of ferrite-based devices include: 1) waveguide-type isolators/circulators [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], where a ferrite slab is integrated within a 3-D waveguide or a Y-junction; 2) stripline-based [15], [16], [17], [18], [19] and microstrip-based [20], [21], [22], [23] isolators/circulators; 3) four-port phase shifters, couplers, and circulators in [24],…”

“…Nevertheless, they require two ferrite disks that increase their volume. Microstrip-based circulators [20], [21], [22], [23] are smaller alternatives to the waveguide-and stripline-based implementations and have been thoroughly investigated with regard to altering their operational bandwidth (BW) [20] and increasing their isolation (IS) [22]. Furthermore, the microstrip Y-junction circulator in [22] exhibits high IS (30 dB) and low IL (0.3 dB).…”

Novel circulator design using substrate integrated coaxial line

“…However, because of its bulky, heavy, and costly metallic structure, the waveguide circulator is not preferred for modern communication purpose that requires lightweight, low cost, and small volume. Several pioneering works have been reported on planar circulators [2][3][4][5][6][7]. In [2], the ferrite is embedded in a substrate-integrated waveguide (SIW), a PCB structure that mimics the waveguide.…”

“…Although the stripline circulator's top and bottom metal sheets serve the same purpose as the waveguide circulator's top and bottom walls, the stripline's open configuration might cause the circuit vulnerable to exterior electromagnetic interference (EMI). In [6], although much simpler in structure, the microstrip circulator also is susceptible to EMI.…”