DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
The HF category brings together all content related to high‑frequency bands, from 160 m through 10 m, with emphasis on practical antennas, propagation, and station hardware. Here you will find compact 40 m verticals, multiband wire antennas, HF QRP transmitters, SDR transceivers, and accessories designed for real‑world home and portable operation. Articles often include measured SWR curves, on‑air reports, and build photos so you can understand how a design will behave before you start cutting wire.
There is a strong focus on getting HF on the air from small Indian plots, apartments, and field locations without sacrificing too much performance. Whether you are preparing for your first HF QSO, improving your 40 m NVIS coverage, or chasing DX on higher bands during good conditions, this section provides tested ideas to upgrade your HF station step by step
Discover the Curumim Transceiver, an ultra-minimalist QRP CW rig for 7.030 MHz that combines a single-transistor crystal oscillator and LM386 audio amplifier into one of the world’s smallest working HF transceivers, ideal for homebrewers, educators, and portable CW enthusiasts
Shortened G5RV antenna design: a compact multiband HF dipole covering 20m–6m bands with ladder-line matching and 4:1 balun for portable or small-yard installs.
DIY EFHW antenna for 40 m–10 m: a 10.1 m multiband end-fed wire with 34 µH loading coil and 49:1 UNUN matching for portable HF and limited-space stations
Build the Shorty Forty — a compact 7 MHz dipole using center-loaded coils to shrink a 40 m antenna to 25 ft while maintaining resonance and solid HF performance in limited space
Build a compact indoor 7 MHz (40 m) HF antenna using coil-loaded wire sections and 75 Ω feed — a stealth, space-saving solution for apartment and indoor ham radio operation
Build a compact 40 m vertical antenna using a 3.4 m radiator and 15 µH base-loading coil — a shortened quarter-wave HF vertical delivering strong 7 MHz DX from limited space.
Explore compact 40 m HF antennas including shortened dipoles and base-loaded verticals for space-limited ham radio setups. Practical designs enable effective 7 MHz operation in small yards, portable, or restricted installations
The GM4JMU shortened dipole uses loading coils to deliver full 40 m band performance in under 10 m span. Ideal compact HF antenna for small gardens, rooftops, and portable ham radio installations.
Aperiodic multiband wire antenna design by HB9KX/DK7ZB: 10.5 m asymmetrical dipole with resistive loading for broadband HF coverage without complex tuning
DIY Active Antenna for superior HF and VHF reception! This DIY electronics project amplifies weak signals to lift hard-to-hear broadcasts out of the noise