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PDF article about a coaxial 1:1 balun, original concept by I4BBE using a quarter-wavelength and the three-quarter-wave adapting sections with the 50-Ohm coaxial cable by I0QM

Show diagrams, winding methods and tables of some 1:1 and 4:1 baluns for 1.8 - 30 MHz suitable for use up to 200W (400W peak) on systems using 50 or 75 ohm coaxial cable input where SWR should not exceed 1.6:1.

Notes on making the W2DU choke balun by placing several ferrite sleeves around a coaxial cable.

A cost effective current-mode 1:1 balun can be constructed from a length of coax and a rod typically used for a broadcast antenna loop-stick, some electrical tape, cable ties, a length of PVC water-pipe and some connectors.

A balun don't depend on use of ferrite beads, but use steel wool to attenuate any RF on the outer braid

A 1:1 current balun by N5ESE

K4TR Manufacture and sell simple dipoles, half square 2 wire phased vertical arrays, end fed zepp antennas, G5RV antennas. 1:1 baluns

Magnetic longwire baluns 1:9 combined with ground, a 1:2 and 1:1 balun connections by ON6MU

An air cored 1:1 balun for 3.5 to 30.0 MHz

a neat 1:1 50 ohm balun for use on HF horizontal wire dipoles.

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

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

A 1:1 to 4:1 switchable balun by N1LO

RF Choke to prevent hf currents on the feedline or...1:1 Choke Balun, sometimes called the "UGLY BALUN"

Circuit diagrams to homebrew different baluns by vk2awx

A 1:1 current balun that offeres a almost flat swr curve from 1 to 30 MHz

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

Building a 1:1 balun, aka un-un, with an Amidon Ferrite toroid core T 200

A mini balun 1:1 4:1 project by WV0H

How to homemade a multi-band HF dipole using 100 meter of speaker wire, 2 strandsm including a homebrew 1:1 choke balun

Cushcraft A3S HF antenna 1:1 balun repair.

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

Homebrew a 1:1 balun consistsing of 4+4 turns of mini coaxial cable over a large ferrite core by m0pzt

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.

The Linked Dipole is a multiband antenna designed for 80/60/40/30/20m bands, optimized for the (tr)uSDX low bands configuration. It incorporates a 1:1 Balun to prevent common mode currents, ensuring balanced operation with coaxial cable. The Balun, wound on an FT140-43 core, achieves 37-40dB attenuation. The design includes a 3D-printable housing for compactness and waterproofing, with labeled link insulators for ease of use. Wire lengths were meticulously adjusted for optimal performance with a 7m pole and 3m rope extension, ensuring the antenna's ends are off the ground for improved behavior. The project includes downloadable printables for DIY construction.

I happened to stumble across some antenna projects showing common mode chokes 1:1 baluns made of some turns of coax wound on T200-2 iron powder toroids.

Make your own dipole for 40 and 80 meters band, assembling standard product parts like 40 meter traps, the 1:1 balun and insulators

The UniBalun is a PCB for building a lightweight antenna transformer (Balun) or impedance converter (UnUn) for low power radios. By soldering jumpers and a toroid core, you can create a 1:1, 1:4 Balun or 1:49, 1:9 UnUn. The latest revision (1.2) includes improved pads and supports both BNC and SMA connectors. Build instructions are available for German speakers.

a 20M quarter-wave vertical antenna with a 6m telescopic mast, 1:1 balun, and spiral-wound driven element. Designed for QRP at 14.285 MHz, the antenna’s performance exceeded expectations, delivering low SWR and surprisingly quiet reception. Initial testing yielded successful contacts with European stations and EC1KR, showcasing its effectiveness. Compact and easy to deploy, the antenna promises to be an excellent portable solution for future hilltop operations.

This practical, hands-on article offers a valuable journey through balun construction for portable antenna systems. The author skillfully navigates from theoretical debates to practical implementation, providing a well-documented DIY process using RG316 micro coax and an FT114-43 toroid core. The step-by-step instructions, complemented by photographs, make this complex technical project accessible to hobbyists. Particularly impressive is the author's focus on lightweight design (just 173 grams) for SOTA field operations. While the final antenna requires minor tuning adjustments, the successful field test during the Pirate Contest demonstrates the effectiveness of this approach. An excellent resource that transforms theory into practical application for ham radio operators.

A multi-band trapped dipole antenna working on 20, 40, 75 and 160 meters band. This project implement a 20 meter trap unadilla reyco KW-20, 40 meter trap Unadilla Reyco KW-40 and a HI-Q 1:1 balun feed.

A C-Pole Antenna for QRPxpeditions describes a DIY C-Pole antenna designed for QRP (low-power) expeditions, inspired by KF2YN’s ground-independent vertical model. After adjustments, it achieved a 1:1 SWR at 14.060 MHz, rising to 2.5:1 at 14.35 MHz. A choke balun, comprising 15 turns of RG8X around a 4” can, was essential for optimal performance. Compact and self-supporting, the antenna enables reliable communication with minimal setup. Contacts included stations across the U.S., and even a 4,600-mile connection to Spain using only 5 watts.

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.

A cost-effective alternative to the Optibeam OB10-3W, a high-performance but expensive tri-band Yagi antenna for the 20, 17, and 15-meter bands. The original Optibeam, featuring three full-size elements on each band, delivers strong forward gain and front-to-back ratio but comes with a high price tag. To address this, a custom design was developed, offering similar performance at a fraction of the cost. Using accessible materials and a simple 1:1 current balun, the homemade version proved highly effective, making it a practical solution.

This project outlines a simple, cost-effective 40m band HF dipole antenna design, ideal for beginners. Constructed with insulated copper wire and a 1:1 balun, it offers a 50-ohm impedance, suitable for both 40m and 15m bands due to the harmonic relationship. Calculations account for a K factor, ensuring optimal length and performance. Antenna modeling with 4NEC2 confirms practical access to both bands, though real-world results may vary. Lightweight materials and straightforward assembly make it an accessible and versatile amateur radio solution.