06-09-2012, 10:39 AM
Active Antennas System
[attachment=33482]
Active Antenna
An active antenna is an antenna that contains active electronic components.
This allows the construction of antennas of limited size and / or wide frequency range.
Most active antennas use antenna parts of minimal conducting area, e.g., a small whip, connected to the active component (usually an FET).
The signal attenuation caused by the antenna-size-to-wavelength mismatch is compensated by an active circuit. The active circuit consists of an impedance translating stage and an optional amplification stage.
This arrangement is especially useful for constructing compact low frequency antennas which, due to budgetary, spacial, or practical requirements (e.g., installation in vehicles), must be downsized. Low frequency signal wavelengths range from one to ten kilometers.
Amplifier Type
The integration of a two port active device with a passive microstrip patch antenna at the input or the output port for the purpose of signal amplification is classified as being of the amplifier type.
When the antenna is at the input port, it is considered to be the source impedance device.
Frequency Conversion Type
When a microstrip antenna is integrated with an active device for the purpose of frequency translation either up or down, it is classified as the Frequency Conversion type.
The conversion efficiency is an important performance parameter.
[attachment=33482]
Active Antenna
An active antenna is an antenna that contains active electronic components.
This allows the construction of antennas of limited size and / or wide frequency range.
Most active antennas use antenna parts of minimal conducting area, e.g., a small whip, connected to the active component (usually an FET).
The signal attenuation caused by the antenna-size-to-wavelength mismatch is compensated by an active circuit. The active circuit consists of an impedance translating stage and an optional amplification stage.
This arrangement is especially useful for constructing compact low frequency antennas which, due to budgetary, spacial, or practical requirements (e.g., installation in vehicles), must be downsized. Low frequency signal wavelengths range from one to ten kilometers.
Amplifier Type
The integration of a two port active device with a passive microstrip patch antenna at the input or the output port for the purpose of signal amplification is classified as being of the amplifier type.
When the antenna is at the input port, it is considered to be the source impedance device.
Frequency Conversion Type
When a microstrip antenna is integrated with an active device for the purpose of frequency translation either up or down, it is classified as the Frequency Conversion type.
The conversion efficiency is an important performance parameter.