Simple High-Gain collinear antenna using coaxial cable

Among the many antenna designs available to amateur radio operators, the coaxial collinear antenna stands out for its rare combination of simplicity, low cost, and excellent performance. Built almost entirely from ordinary coaxial cable, this antenna is capable of producing real gain over a standard quarter-wave vertical while maintaining an omnidirectional radiation pattern that is ideal for local and regional VHF and UHF communication.

The antenna shown in the below attached diagram is a classic example of a vertically stacked coaxial collinear design. Variations of this antenna have been built and refined by radio amateurs around the world for decades, and many commercial base-station antennas use the same underlying principle, hidden inside fiberglass radomes. What makes this design especially attractive is that it requires no traps, coils, or complex matching networks. When built carefully, it works “right the first time” and delivers consistent results.

Simple High-Gain collinear antenna using coaxial cable

3 x 5/8 Collinear antenna for 435 MHz UHF Band

For UHF repeater systems operating around 435 MHz, antenna efficiency and gain are critical. Simple vertical antennas often do not provide sufficient performance, especially when wide coverage and reliable signal strength are required. To address this need, a UHF collinear antenna design adapted from the well-known Diamond BC-200 has been developed and documented by Kostadin Evstatiev (LZ1DJ).This 3 x 5/8 Collinea antenna is intended specifically for the 420–440 MHz band and provides high gain without requiring post-installation tuning when constructed accurately.

3 x 5/8 Collinear antenna for 435 MHz UHF Band

Hourglass Loop Antenna : A Stealthy Performer for VHF and UHF

If you’re hunting for a high-performance antenna that doesn’t look like a metallic porcupine, the Hourglass Loop (popularized by K4ERO) is a fantastic weekend project. It is essentially two delta loops stacked and fed in-phase, resulting in a bidirectional pattern with about 5 dB of gain over a standard dipole.

Unlike a typical 1-wavelength loop, the hourglass uses a 2-wavelength wire. The crossing point in the center acts as a phasing section, forcing currents in the top and bottom horizontal segments to be in phase. This creates a narrow vertical radiation pattern that puts your signal exactly where it needs to be: on the horizon.

Hourglass Loop Antenna : A Stealthy Performer for VHF and UHF

DIY 3-Element 433 MHz Yagi Antenna for Amateur Radio

Directional antennas can dramatically improve signal quality in the 433 MHz band. Whether you work with amateur radio, telemetry, LoRa projects, remote sensors, or experimental RF systems, a compact Yagi antenna is often one of the simplest upgrades you can make.

This particular 3-element 433 MHz Yagi Antenna design stands out because it combines good forward gain with straightforward construction. It uses a reflector, a loop-driven element, and a director mounted on a compact boom. The result is a lightweight antenna capable of significantly improving range and reducing unwanted interference.

The design shown above is based on proven dimensions used by radio amateurs and antenna experimenters. Its geometry is optimized specifically for the 70 cm UHF band near 433 MHz.

DIY 3-Element 433 MHz Yagi Antenna for Amateur Radio