Active Antenna vs Passive Antenna-Difference between Active Antenna and Passive Antenna
This page on Active Antenna vs Passive Antenna describes difference between Active Antenna and Passive Antenna. The other difference between various terms are provided here.
Passive antennas contain radiating element only such as ceramic patch or helix structure. Passive matching network is often used in order to match electrical connection with 50 Ohm impedance line. Passive antennas do not require power supply.
Active antennas need power supply. It usually consume 3 to 20 mA in GPS system.
It usually houses LNA along with antenna circuitry part.
This is beneficial in two aspects:
• The losses of cable length after LNA device will not affect overall noise figure of GPS receiver part.
• LNA portion with antenna will help reduce overall noise figure of system which results into better sensitivity.
Active type of antenna is always favourable when RF cable length between antenna and receiver exceeds 10cm. Only concern should be taken care is that LNA does not overload the receiver.
|• It is more tolerant to minor impedance mismatch or cable length than
• It helps to keep the receiver noise figure low
• It is less affected by jamming into the antenna cable than a passive antenna (if equipped with filter)
|• It does not add anything to the power budget
|• It needs more power (about 10 to 60 mW) compare to passive antenna
|• Antenna must be connected with a carefully designed microstrip or stripline
of max. 10 cm to the GPS receiver toensure good GPS performance
• Jamming signals are coupled into the microstrip or stripline negatively affect the performance
• RF design experience is required to properly design a passive antenna.
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