In which frequency band does a search and rescue transponder operate?

9 GHz.

SART operates in the 9.2 to 9.5 GHz frequency band, which is the Super High Frequency (SHF). The SHF band extends from the 3 GHz to 30 GHz, with wavelength from 1 to 10 centimeters.

This frequency range is known as the microwave range, often referred to as the X wave range.

Because the wavelength is just few centimeters, this narrow radio beam works well with horn and parabolic (microwave dishes) antennas, which facilitates line-of-sight transmissions, somewhat like the VHF band waves.

If you position the SHF antenna as high as possible, the propagation range will increase with height.

For more info, see Wikipedia's articles on Search and rescue transponder and Super high frequency.

Good overview is on Blue Seas site article, SART - Search and Rescue Transponder.

An important reference is provided by the International Telecommunications Union (ITU) in the RECOMMENDATION ITU-R M.628-3, entitled TECHNICAL CHARACTERISTICS FOR SEARCH AND RESCUE RADAR TRANSPONDERS,

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How should the signal from a Search And Rescue Radar Transponder appear on a RADAR display?

A series of 12 equally spaced dots.

A SART, when interrogated by a 9GHz X-band radar, will sweep rapidly (0.4 μS) through the band once and then back slowly (7.5 μS).

This will happen 12 times, with each producing a "dot" as the frequency will match that of the radar, thus producing a line of 12 dots.

For more info and radar display, please see Wikipedia's article on Search and rescue transponder

To see full screen radar display, please see Wikipedia's SART Radar Display

For active radar view, see Japan Radio Co. Ltd's article on SART(SEARCH AND RESCUE RADAR TRANSPONDER) JQX-30A

Highly recommended is the pdf user manual for SART, to get realistic details, for McMurdo's S4 Rescue SART Search and Rescue Transponder.

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What is the purpose of the SART’s audible tone alarm?

It informs survivors that assistance may be nearby.

SART's have a light as well as an audible signal to indicate to survivors that it has been "interrogated" by a radar. This will inform survivors that a ship is in the nearby area.

The SART's beeps every 12 seconds if no radars detected it, and switches to beeping every 2 seconds when a radar sends a signal to the SART unit.

For more info, please see Marine Insight's site for article on What is Search and Rescue Transponder (SART)?

Short but comprehensive overview is on egmdss site's article on The basis of SART.

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Which statement is true regarding the SART?

This is a 9 GHz transponder capable of being received by vessel’s X-band navigational RADAR system.

SART operates in the 9.2 to 9.5 GHz frequency band, which is the Super High Frequency (SHF). The SHF band extends from the 3 GHz to 30 GHz, with wavelength from 1 to 10 centimeters.

This frequency range is known as the microwave range, often referred to as the X wave range.

Because the wavelength is just few centimeters, this narrow radio beam works well with horn and parabolic (microwave dishes) antennas, which facilitates line-of-sight transmissions, somewhat like the VHF band waves.

If you position the SHF antenna as high as possible, the propagation range will increase with height.

For more info, see Wikipedia's articles on Search and rescue transponder and Super high frequency.

Good overview is on Blue Seas site article, SART - Search and Rescue Transponder.

An important reference is provided by the International Telecommunications Union (ITU) in the RECOMMENDATION ITU-R M.628-3, entitled TECHNICAL CHARACTERISTICS FOR SEARCH AND RESCUE RADAR TRANSPONDERS, (see Point 1)

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At what point does a SART begin transmitting?

If it has been placed in the “on” position, it will respond when it has been interrogated by a 9-GHz RADAR signal.

A SART beacon responds when "interrogated" by a X-Band (9GHz) RADAR system found on craft used for maritime search and rescue.

It automatically reacts to the radio wave emissions from a radar. Works like the RFID chip which responds with information when receiving radio signals. To respond to a radar, SART must be switched ON manually.

SART signal to a radar triggers creation of 12 blips on the radar screen. The blips turn to circles as the SART unit gets closer to the radar.

For more info, see Wikipedia's article on Search and rescue transponder

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How can a SART’s effective range be maximized?

The SART should be held as high as possible.

Elevation will make the SART's signal more visible to the radar station.

SART, the Search and Rescue Transponder, radiation is horizontal and omnidirectional, and looks like a big doughnut. As horizontal radiation works in the "line of sight " transmission pattern, then the higher the antenna the longer the range.

Because the wavelength is just few centimeters, this narrow radio beam works well with horn and parabolic (microwave dishes) antennas, which facilitates line-of-sight transmissions, somewhat like the VHF band waves.

If you position the SHF antenna as high as possible, the propagation range will increase with height.

• How fast the SART gets in the water won't affect its range.
  
• SARTs don't have high/low power switches.
  
• X band radar is dual-polarized. Horizontal or vertical is irrelevant.

For more info, check out SART specifications

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