CI 121

The Comant CI 121 is a four-hole, top-mount VHF communications whip antenna designed for light fixed-wing single-engine, multi-engine, and helicopter applications. It covers the 118–137 MHz civil aviation COM band and uses a 50 Ω BNC female connection, making it a well-established choice for aircraft VHF communications installations where the CI 121 is specified or otherwise approved for use.

Designed with a cast housing and fiberglass whip, the CI 121 combines a compact, lightweight installation with vertical polarization and an omnidirectional radiation pattern. The antenna is rated for up to 50 watts RF power with a maximum specified VSWR of 2.5:1.

Comant describes the CI 121 as equivalent in general configuration to the CI 109, but with a smaller-diameter whip and lower weight. Its four-through-hole mounting arrangement and BNC connector make it suitable for top mounting on supported aircraft installations.

The CI 121 is qualified to RTCA DO-160D environmental requirements and carries FAA TSO-C37d and TSO-C38d approvals. Published environmental specifications include operation from -55°C to +85°C and altitudes up to 50,000 ft.

Key Features

• Frequency range: 118–137 MHz
• Application: VHF aircraft communications
• Impedance: 50 Ω
• Connector: BNC female
• VSWR: 2.5:1 maximum
• Polarization: Vertical
• Radiation pattern: Omnidirectional
• Maximum RF power: 50 W
• Mounting: Four-through-hole, top mount
• Construction: Cast housing with fiberglass whip
• Finish: Glossy white
• Height: 19.0 in
• Weight: 0.60 lb
• Operating temperature: -55°C to +85°C
• Maximum published altitude: 50,000 ft
• FAA TSO: C37d, C38d
• Environmental qualification: RTCA DO-160D
• Gasket: B12607-3 cork-neoprene

Designed for Aircraft VHF COM Installations

For aircraft owners, avionics shops, and maintenance professionals looking for a dedicated 118–137 MHz VHF communications antenna, the CI 121 provides a straightforward combination of standard aviation impedance, BNC connectivity, lightweight construction, and documented FAA/RTCA qualifications.

Always verify the exact part number, mounting configuration, aircraft applicability, and current approved installation data before ordering or installation. Comant specifically directs installers to use the factory-supplied drawings and specifications for installation.