DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
Detailed technical guides for building and deploying high-performance HF wire antenna. This section covers a wide range of designs, including end-fed half-waves (EFHW), off-center fed dipoles (OCFD), G5RVs, and long-wire antennas. Learn how to optimize your antenna for specific bands, understand the role of 49:1 and 9:1 ununs, and discover methods for effective antenna tensioning and weatherproofing
The UA4HAZ 20-meter antenna is a clever modification of the classic half-wave dipole, designed specifically for radio amateurs struggling with limited horizontal space. By utilizing a “folded” or inverted-U geometry, this antenna maintains a resonant length for the 14 MHz band while significantly reducing its physical footprint. This guide covers the theory, construction, and proper coaxial feed techniques required to get this efficient radiator on the air.
Height is often the biggest hurdle for Hams, but what if you could trade verticality for horizontal real estate? This detailed guide explores the 21.3m-per-side hexagonal loop—a low-profile powerhouse that offers multi-band performance with minimal visual impact.
Tired of antenna tuners? The T2FD antenna offers incredible wideband performance from 3-30 MHz. This guide breaks down the essential components—from non-inductive resistors to spreader geometry—to help you build a reliable, low-noise “all-bander.”
Unlock elite DX performance with the Switchable Delta Loop. This detailed guide covers everything from the 141-foot 40m foundation to the ingenious 18-inch tuning tails that enable seamless 30m operation. Perfect for hams seeking a low-angle radiator with a manageable footprint
The Doublet Dipole remains a favorite for hams seeking multiband efficiency without complex hardware. By utilizing balanced feed lines and a 4:1 balun, this antenna design overcomes the limitations of traditional coax-fed dipoles. Our guide breaks down the essential formulas and provides a detailed dimension table for the 80m, 40m, 20m, and 15m amateur radio bands for your next project.
The Half Square has been quietly delivering low-angle DX gain to operators who know about it, while remaining invisible to everyone else — including curious neighbours. Shaped like the Greek letter π, it uses two quarter-wave verticals fed in phase through a half-wave horizontal section, matches directly to 50-ohm coax without a tuner, needs no radials, and can beat an Inverted-V by 4 dB toward the horizon. Here is everything you need to build one
If you are running a multiband doublet or any antenna with a tuner, ladder line will outperform coax on almost every band. Here is how to build your own from scratch — four proven designs, common materials, and every practical detail from spacer drilling to routing it through the shack wall.
A simple length of wire can unlock nearly the entire HF spectrum—and that’s exactly what the multi-band doublet antenna delivers. Using low-loss ladder line and an antenna tuner, this classic balanced antenna provides efficient coverage from 6 m through 160 m without the complexity of multiple resonant dipoles. Whether installed in a backyard or deployed in the field, the doublet remains one of amateur radio’s most versatile and enduring wire antenna solutions.
Learn how a fan dipole (parallel dipole) antenna lets you operate on two HF bands from a single feedline with no tuner. Includes the 468 formula, component breakdown, band pairing tips, and step-by-step building guide
The Extended Lazy-H antenna is one of amateur radio’s classic wire antenna designs, combining simplicity with reliable multiband performance. First published in the October 1955 issue of QST magazine, this antenna was intended to provide efficient HF operation using balanced construction and open-wire feed line.