In wireless communication system, pre-amplifier is located in front of power amplifier for the purpose of amplifying the signal of the IF stage low-level output. In this work, X-band pre-amplifier modules were fabricated and its RF characteristics were investigated for application to X band radar system.
Firstly, 4-way power dividers were designed for application to preamplifier module. According to measured results, the return loss characteristic of the divider was –18 dB at X-band up-link frequency bandwidth. In the frequency range of 7.9 to 8.4 GHz, S21 and S31 showed a value of –7.1±0.1 dB and –6.8±0.3 dB, respectively. The power divider showed equal phase division characteristic in the above frequency range. And the isolation characteristic of the power divider was –6 ~ -14 dB in the above frequency range. The isolation characteristic was improved by connecting resistor between output ports. The divider was used for power combining and dividing of the X-band pre-amplifier. The pre-amplifier module employing the above power divider showed an output power level of 11.5 dBm at X-band.