This article continues from Ambient noise measurement using whip on vehicle – #1 – estimate Antenna Factor with a case study for the active antenna electronics.
For this discussion, I will use the amplifier developed at A high performance active antenna for the high frequency band, but applied to the antenna described at Ambient noise measurement using whip on vehicle – #1 – estimate Antenna Factor.
Let’s assume that the antenna + amplifier will be used with a HF receiver with Noise Figure 6dB, Teq=864.5K.
From (Martinsen 2018) Fig 3.8, the amplifier internal noise at the output terminals is -118dBm in 100kHz @ 3.5MHz. That implies that the amplifier Noise Temperature is 857.93K. The amplifier has 6.4dB voltage gain which needs to be subtracted from the AF calculated for unity gain (at the amplifier input terminals). Continue reading Ambient noise measurement using whip on vehicle – #2 – active antenna electronics