Hadi Razavipour

Bio: Hadi Razavipour is an academic researcher from Isfahan University of Technology. The author has contributed to research in topics: Circulator & Return loss. The author has an hindex of 2, co-authored 2 publications receiving 12 citations.

A new high-power, dual-band, E-plane, ferrite circulator

Abstract: The design, simulation and enhancing performance of a new structure for X-band high-power, low-loss, low-bias, triangular-ferrite waveguide circulator is presented. Dual circulation property is obtained by triangular shape of ferrite post. The effects of circulator's structure parameters, such as ferrite parameters and magnetic DC bias, on isolation, insertion loss and return loss of circulator are discussed. 20dB return loss, 20dB isolation and 0.1 dB insertion loss in dual frequency in X-band (8.2 Ghz & 10.4 Ghz) with only a magnetic bias of 10 Oe are obtained from CST Microwave Studio and Ansoft HFSS simulations which have good agreement to each other and shows remarkable response of those type of circulators.

A New Dual-Band High Power Ferrite Circulator

Abstract: The design, simulation and performance enhancement of a new structure for X-band high-power, low-loss, low-bias, triangularferrite waveguide circulator are presented. Dual circulation property is obtained by triangular shape of ferrite post. The effects of circulator’s structure parameters, such as ferrite parameters and magnetic DC bias, on isolation, insertion loss and return loss of circulator are discussed. The HFSS software is used for simulating the circulators. Final dual band designs with 20 dB return loss, 20 dB isolation and 0.1 dB insertion loss in dual frequency in X-band (8.2 GHz and 10.4GHz) with only a magnetic bias of 10Oe are obtained.

Analysis and design of new active quasi circulator and circulators

Abstract: This paper introduces two new type active quasi circulators and three new type active circulators which use the out- of-phase power divider/combiner, symmetric/anti-symmetric couplers and generic unilateral ampliflers. The proposed circuits are full-symmetric and composed of conventional microwave devices. Analytical relations for active quasi circulator modules are described. These modules have many variations and can be used for very wide frequency range depending on the type of the employed unilateral amplifler, power divider/combiner and symmetric/anti-symmetric couplers. Based on the proposed conflgurations, analysis and design of n-port active circulators are presented. Also they can be used in MMICs as active quasi circulators, active circulators and in other high frequency applications.

New Concept Validation of Low-Loss Dual-Band Stripline Circulator

Abstract: This paper proposes a new design methodology of dual-band stripline circulator for wireless communications applications. As far as the monoband classic circulator is based on coupling the counter-rotating fundamental modes, the operating principle of dual-band phenomenon is based on studying both fundamental and upper resonant modes within ferrite disks. Electromagnetic (EM) simulations have shown that two categories of dual-band operation could be obtained: simple (unidirectional) and left-handed /right-handed (LH–RH) circulators. The application dedicated to these two original concepts will be discussed, and simulation results will be ensured by the measurement of two prototypes in order to validate the methodology’s reliability.

Study of nonreciprocal devices using three- strip ferrite coupled line

Abstract: This paper presents the investigations of nonreciprocal devices employing a novel ferrite coupled line junction. The structure is designed using coplanar line technology with the ground half-planes reduced to the strips. The investigated junction is composed of one ferrite section placed in between of two dielectric sections. In the ferrite section the longitudinally magnetized ferrite slab is located at the top or the bottom of the strips and is covered with the dielectric layers. In the dielectric sections the ports of the junctions are located. The wave parameters and fleld distributions of the modes propagated in the dielectric and ferrite sections are obtained from spectral domain approach. In order to determine the scattering matrix of the junction the mode matching method is utilized. The investigation of the circulator and isolator designed based on the S- matrix of the junction are presented. The obtained results are verifled by comparing them with HFSS simulations and own measurements of the fabricated devices. In both cases a very good agreement is observed.

Magnetically tunable substrate integrated waveguide bandpass filters employing ferrites

Abstract: A novel tuning solution for planar reconfigurable microwave filters is presented. The proposed filters are implemented using substrate integrated waveguide (SIW) technology featuring compact size, low cost, high Q, and high power-capacity. Tunablity of the proposed reconfigurable filters is achieved by adjusting dc-magnetic bias applied to the ferrite material. Compared to the previously reported reconfigurable filters based on electrical adjustment enabled by mechanical modifications, the proposed filters offer a relatively wide tuning range and stable tenability, while dramatically reducing the complexity of external control system. Effects of filters parameters' including the ferrite material, magnetic DC bias, and SIW configuration, on reconfigurable performance are discussed. Simulation examples of single-circulator and double-circulators tunable bandpass filters are realized using EM simulations for demonstrating the underlying principle.

Design of X-band H-plane waveguide Y-junction circulator

Abstract: This paper presents an approach to the design of three-port H-plane waveguide Y-junction circulator with two partial height ferrite posts in the junction region which has the advantages of high isolation and low insertion loss. With 9.375GHz center frequency and 400MHz bandwidth, the X-band waveguide circulator designed with the approach could be used in microwave measurement systems, whose VSWR is less than 1.2, insertion loss is less than 1dB and isolation is more than 20dB, which could be used in medium power systems and high power systems.