Investigations of Four-Port Circulator Utilizing Cylindrical Ferrite Coupled Line Junction

Abstract

Abstract-In this paper the numerical and experimental investigations of four-port circulator utilizing longitudinally magnetized cylindrical ferrite coupled lines (CFCL) section are presented for the first time. In comparison to earlier models the proposed structure of circulator utilizes multilayer magic-T junction cascaded with cylindrical ferrite section of π/4 Faraday angle. The advantage of utilization of cylindrical section over the planar one is the possibility to design shorter ferrite junctions ensuring lower insertion losses. Moreover, the multilayer magic T-junction allows to improve performance of the proposed circulator by omitting the bandwidth limitation which exists in commonly used hybrid couplers with air-bridges. In the analysis of CFCL junction the full wave hybrid approach combining finite difference frequency domain method with method of moments and mode matching technique is applied. The planar feeding structures of circulator are designed with the use of commercial software. The simulated results of the entire circulator are compared with the measurement results of the fabricated prototype and a good agreement is achieved.

Nonreciprocal Devices Utilizing Longitudinally Magnetized Ferrite Coupled Lines

“…2(b). However, due to the double signal passing through the ferrite section, the losses of the structure are two times ✹ ❆❞✈❛♥❝❡❞ ❊•❡❝tr♦♠❛❣♥❡t✐❝ ❲❛✈❡s In order to determine the scattering parameters of the FCL junction, two different hybrid techniques have been proposed and developed ( [12,[16][17][18]) (see Fig. 3).…”

“…As a result of the analysis, the dispersion characteristics of the ferrite line, the gyromagnetic coupling coefficient, and the scattering parameters of the ferrite junction are obtained. The second method is based on a combination of SDA with mode-matching (MM) technique ( [12,18]). In this approach, the SDA is utilized to determine the propagation coefficients and field distribution of two fundamental modes in ◆♦♥r❡❝✐♣r♦❝❛• ❉❡✈✐❝❡s ❯t✐•✐③✐♥❣ ▲♦♥❣✐t✉❞✐♥❛••② ▼❛❣♥❡t✐③❡❞ ❋❡rr✐t❡ ❈♦✉♣•❡❞ ▲✐♥❡s ✺ ✶✵✳✺✼✼✷✴✻✶✺✷✹ a dielectric and ferrite section.…”

“…As can be seen, the magnetic field vectors of the dielectric modes are orthogonal to each other in the areas above and below the strips in the symmetry plane AA ′ of the structure. According to the definition of coupling coefficient (12), if instead of one of these layers the ferrite material is introduced, the optimal gyrotropic coupling effect will be obtained.…”

“…These make possible to design shorter ferrite junctions ensuring lower insertion losses in comparison to planar ones. This junction was successfully applied to realization of nonreciprocal devices such as isolators and circulators [11,12]. This chapter presents the authors' recent research on the nonreciprocal devices utilizing longitudinally magnetized FCL junction.…”