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Step-By-Step Construction of a 4:1 Current-Type Guanella Balun by W1CG

A model of a Guanella 1:1 VHF choke balun using a FT140-61 core

A cost effective current-mode 1:4 balun can be constructed from two lengths of coax, two ferrite rods, some electrical tape, cable ties, a length of PVC water-pipe and some connectors. This form of 1:4 current-mode balun is named after G. Guanella.

This article proposes a lossy transmission line model of a practical Guanella 1:1 balun that is effective for all frequencies within and immediately adjacent to the pass band

This article reviews the proposition that a 4:1 current balun in the style of Guanella can be constructed with both pairs of windings sharing a common magnetic circuit.

1:1 Ruthroff voltage balun using a T200-2 Toroid core

Classical coax-fed, off-center-fed dipole, feeded with a 4:1 Guanella balun

An interesting article on guanella baluns that cover several aspects of homebrewing 1:1 and 4:1 current baluns by KN9B

This EXCEL Program Worksheet calculates the common-mode impedance of a 1:1 Guanella (current) balun which is placed at the feed point of a balanced antenna system fed via coax.

This page provides a detailed guide on the Guanella Current Balun for ham radio operators. The author shares very nice schematics, photos, and explanations on the construction and use of this type of balun. The content explains when a balun is needed and how it can help with common-mode currents in antenna systems. It also discusses the construction process, including winding the balun around a ferrite core. This resource is useful for hams looking to improve their antenna systems and reduce common-mode currents for better performance. This article is in Dutch.

This comprehensive three-part guide examines baluns (balanced-to-unbalanced devices) and their critical role in ham radio antenna systems. The author explains how baluns prevent common-mode currents on feedlines, which can distort radiation patterns and cause unwanted RF in the shack. Various balun types are analyzed, including coiled coax chokes, ferrite-core designs (W2DU), and toroidal-wound versions (Guanella/Ruthroff). Construction techniques for 1:1, 4:1, 6:1, and 9:1 current baluns are provided with practical guidance on wire selection, winding methods, and ferrite core properties. The article emphasizes that proper balun implementation is essential for optimal antenna performance, especially with directional arrays.