Landing Radio Altimeter – The Essential Tool for Small Aircraft

For most of the small aircraft aviator, they might have the difficulty in the landing radio altimeter (the standard 4.3 GHz radio-altimeter). Therefore, the new design will improve the recently accuracy and altitude coordination.


As we know, most of the current made radio-altimeter only limited to a few feet, and this will increase the frequency of accidents happening for the small craft.


Above is the principle of operation for a radio altimeter. Most of the radio altimeters are frequency-modulated radars. This means it’s often get a delay in between the received signal, which will greatly reduced the accuracy of the small aircraft.

Below here is the new design for radio-altimeter.


From here, we can see that the transmitter modulator includes two triangular oscillators:

  • The main sweep at 150 Hz
  • The dither at 15Hz

We will set the dither amplitude to 10% of the main sweep amplitude. The VCO is followed by two amplifier-buffer stages, which using another BFP420 bipolar transistor and a MGF4918 HEMT. A RF power about 40mW at 4.3 GHz will be produced latter. [link]

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