Sirio Aircraft Antenna

Sirio Aircraft Antenna - VHF Aeronautical Communication in the 118-137 MHz Frequency Band

The Sirio MD 118-137 Aviation antenna is designed for operation within the 118-137 MHz VHF aeronautical communication frequency range. The MD 118-137 model features a half-wave dipole configuration with a loaded radial. Its electrical characteristics include a nominal impedance of 50 ohms, direct centre feeding and vertical polarization. The antenna is specifically recommended for installation on light aircraft.

What Are the Main Features of the Sirio MD 118-137 Aviation Aircraft Radio Antenna?

The antenna consists of two principal elements: the radiating whip and the loaded radial. The whip is manufactured from black-chromed stainless steel, while additional construction materials include stainless steel, nylon, chromed brass and Zamac. One of the distinguishing features of the MD 118-137 Aviation is that its loaded radial eliminates the need for a metallic ground plane. The antenna has an approximate overall length of 760 mm and weighs approximately 330 g.

What Are the Technical Specifications of the Sirio MD 118-137 Aviation Antenna?

The electrical specifications of the Sirio aircraft antenna define its radio frequency operating range and fundamental connection requirements. The model is designed for frequencies between 118 and 137 MHz and has a nominal impedance of 50 ohms. Its specified antenna gain is 2.15 dBi, equivalent to 0 dBd. The standing wave ratio is specified as no greater than 1.5, while the maximum permissible input power is 50 W.

Electrical Specifications of the Sirio VHF Airband Antenna

• Model: Sirio MD 118-137 Aviation.
• Product code: SIR-137-999.
• Antenna type: Half-wave dipole with loaded radial.
• Frequency range: 118-137 MHz.
• Impedance: 50 ohms.
• Polarization: Vertical.
• Radiation pattern in the H-plane: 360 degrees, omnidirectional.
• Antenna gain: 2.15 dBi or 0 dBd.
• Standing wave ratio (SWR): Maximum 1.5.
• Maximum input power: 50 W.
• Feeding system: Direct.
• Feed position: Centre.

These electrical characteristics collectively describe the radio frequency properties of the MD 118-137 Aviation antenna. The frequency range and impedance are important when selecting the connected radio equipment, while antenna gain, radiation pattern and polarization define its radiation characteristics. The maximum input power limit of 50 W must be observed during operation.

Sirio Aircraft Antenna Dipole Construction and Radiation Characteristics

Why Does the Sirio MD 118-137 Antenna Use a Loaded Radial?

The MD 118-137 Aviation uses a half-wave dipole configuration incorporating a loaded radial. A documented characteristic of this design is that the antenna does not require a metallic ground plane for operation. The radial measures 165 mm in length, while the overall antenna length is approximately 760 mm. The loaded radial forms an integral part of the antenna construction and must be considered together with the radiating whip when assessing the mechanical configuration of the model.

Vertical Polarization and Omnidirectional Radiation

The Sirio aircraft antenna features vertical polarization. Its radiation pattern in the horizontal, or H-plane, is specified as 360-degree omnidirectional. This specification describes the antenna's radiation characteristics in the horizontal plane. The stated gain of 2.15 dBi and vertical polarization are both fundamental electrical characteristics of the model. The antenna uses a direct, centre-fed system.

What Should You Know About Antenna Gain, Impedance and Standing Wave Ratio?

Sirio MD 118-137 Aviation Antenna Gain and 50-Ohm Impedance

The Sirio MD 118-137 Aviation has an antenna gain of 2.15 dBi, also expressed as 0 dBd. These values represent gain measurements referenced to different antenna standards. The antenna's nominal impedance is 50 ohms, an important parameter when checking the electrical matching between the radio equipment and the antenna system. The antenna is supplied with RG58 C/U coaxial cable, with a standard cable length of 5 metres.

What Is the VSWR of the MD 118-137 Aviation VHF Antenna?

The antenna has a specified SWR, also referred to as VSWR, of no greater than 1.5. The standing wave ratio is a parameter used to characterize impedance matching within a radio frequency system. For the Sirio MD 118-137 Aviation, the operating frequency range of 118-137 MHz, nominal impedance of 50 ohms and maximum SWR of 1.5 are important electrical specifications. The maximum permissible input power is 50 W, and this limit must not be exceeded.

Sirio MD 118-137 Aviation Mechanical Construction and Materials

The radiating whip of the Sirio aircraft antenna is manufactured from black-chromed stainless steel. Additional structural materials include 17/7 PH stainless steel, nylon, chromed brass and Zamac. The metal components are manufactured from brass or steel. Material selection and mechanical specifications are also relevant when planning installation on an aircraft.

What Are the Dimensions and Wind Resistance of the Sirio Aircraft Antenna?

• Overall length: Approximately 760 mm.
• Radial length: 165 mm.
• Weight: Approximately 330 g.
• Wind resistance: 220 km/h.
• Mounting hole diameter: 14 mm.
• Maximum mounting metal sheet thickness: 1.5 mm.
• Radiating whip: Black-chromed stainless steel.
• Additional structural materials: 17/7 PH stainless steel, nylon, chromed brass and Zamac.

The specified wind resistance of 220 km/h is one of the mechanical characteristics of the model. Installation must also take into account the required mounting hole diameter of 14 mm and the maximum metal sheet thickness of 1.5 mm. The overall antenna length and weight are additional specified parameters that must be checked when selecting the installation position.

How Is the Sirio Aircraft Antenna Installed and Connected?

Installing the Sirio MD 118-137 Antenna on an Aircraft

The MD 118-137 Aviation antenna should be positioned as far away as possible from the human body. Installation requires a 14 mm diameter hole in a metal sheet with a maximum thickness of 1.5 mm. Any paint must be removed from the contact area to ensure proper metal-to-metal electrical contact. The antenna base and radiating element must then be secured, ensuring that all components are correctly tightened.

Which Cables and Connectors Are Supplied with the Aircraft Radio Antenna?

The Sirio MD 118-137 Aviation is supplied as standard with a 5-metre RG58 C/U coaxial cable. The cable is terminated with an FME female connector. A BNC male to FME male adapter is also included. Alternative cable lengths and connector types can be requested. When connecting the antenna to radio equipment, both the cable specifications and connector configuration must be checked.

What Should Be Considered When Routing the Antenna Cable?

The coaxial cable must be routed so that it does not interfere with or obstruct the pilot's movements. The cable running between the radio equipment and the antenna must be properly secured. During antenna operation, the maximum permitted input power of 50 W must not be exceeded. The tightness of the installed components should be checked periodically. Compliance with these installation requirements is necessary during both fitting and subsequent operation.

Advantages and Installation Requirements of the Sirio MD 118-137 Aviation

The following characteristics and requirements are directly associated with the antenna's specified construction and intended application.

• Advantage: The loaded radial eliminates the need for a metallic ground plane.
• Advantage: The model is recommended for installation on light aircraft.
• Advantage: A 5-metre RG58 C/U cable and BNC-FME adapter are included in the specified configuration.
• Requirement: The mounting metal sheet must not exceed 1.5 mm in thickness.
• Requirement: A 14 mm diameter mounting hole is necessary.
• Requirement: Input power must not exceed 50 W.
• Requirement: Cable routing must not obstruct the pilot's movements.

When selecting the antenna, the frequency range, 50-ohm impedance and connector configuration must be checked alongside the mechanical installation dimensions. We recommend the Sirio MD 118-137 Aviation for applications that meet its specified electrical and installation requirements.

Sirio Aircraft Antenna - Frequently Asked Questions (FAQ)

• What frequency range does the Sirio MD 118-137 Aviation operate in?
  The antenna is designed for the 118-137 MHz VHF aeronautical communication frequency range.
• What is the antenna impedance?
  The MD 118-137 Aviation has a nominal impedance of 50 ohms.
• What type of antenna is the Sirio MD 118-137 Aviation?
  It is a half-wave dipole antenna equipped with a loaded radial.
• Does the antenna require a metallic ground plane?
  No. The loaded radial eliminates the need for a metallic ground plane.
• What is the antenna gain?
  The specified antenna gain is 2.15 dBi, equivalent to 0 dBd.
• What is the maximum input power?
  The maximum permissible input power is 50 W.
• How long is the coaxial cable?
  The standard configuration includes a 5-metre RG58 C/U coaxial cable. Alternative cable lengths can be requested.
• Which connector does the antenna use?
  The coaxial cable has an FME female connector, and a BNC male to FME male adapter is included.
• What mounting hole diameter is required?
  A 14 mm diameter mounting hole is required in a metal sheet with a maximum thickness of 1.5 mm.
• What is the wind resistance of the Sirio MD 118-137 Aviation?
  The specified wind resistance is 220 km/h.
• What polarization does the antenna use?
  The MD 118-137 Aviation uses vertical polarization and has a 360-degree omnidirectional radiation pattern in the H-plane.

Summary: When Do We Recommend the Sirio MD 118-137 Aviation Antenna?

We recommend the Sirio aircraft antenna MD 118-137 Aviation model for VHF aeronautical radio communication in the 118-137 MHz frequency range. Its half-wave dipole configuration, loaded radial, 50-ohm impedance and 2.15 dBi gain are among its defining electrical characteristics. The overall length of 760 mm, approximate weight of 330 g and wind resistance of 220 km/h are important mechanical specifications.

Installation requires a 14 mm mounting hole, a metal sheet no thicker than 1.5 mm and proper cable securing. The supplied 5-metre RG58 C/U cable and BNC-FME adapter provide the specified connection accessories. If you are looking for a VHF antenna operating between 118 and 137 MHz for a light aircraft, we recommend comparing the technical specifications and installation requirements of the Sirio MD 118-137 Aviation with those of your intended installation.