DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
Master the construction of the high-performance Sleeve Dipole antenna using only coaxial cable. This technical deep-dive explains how the “sleeve” acts as a decoupling balun, providing a clean radiation pattern and low SWR for VHF/UHF and HF applications without external chokes
The broadband butterfly (bi-square) antenna uses two connected square loops to deliver stable 50–75 Ω impedance, low noise, and several dB gain over a dipole across VHF/UHF bands. Simple bidirectional design requires no tuning and scales easily for 144 MHz and 430 MHz operation