Multichannel Radiometer Frontend Based on Bandwidth Synthetic Technology

A multichannel radiometer frontend, which can improve the radiometer sensitivity and utilization of the frequency band dramatically, is proposed based on the principle of bandwidth synthetic technology. The multichannel radiometer, called multichannel bandwidth synthetic radiometer (MCBWSR), consists of multiple conventional radiometer channels, and the frequency bands of all the channels are synthesized by the bandwidth synthesizer before the detector. The synthesized bandwidth of the synthesizer can reach a maximum of the sum of all the bandwidths. The operating frequency can also be selected flexibly using the frequency conversion technology. An analysis of the sensitivity $\Delta T_{syn}$ of the MCBWSR is deduced in terms of the conventional single-channel radiometer sensitivity $\Delta T_{i} $ . The relationship of sensitivity between the conventional single-channel radiometer and MCBWSR is validated using an RF simulator. To verify the analysis, three experiments are implemented on a direct detection radiometer, a heterodyne radiometer, and a dual-channel bandwidth synthetic radiometer (DCBWSR) receiver, respectively. The experimental results are presented, and the sensitivity among them is compared. These results indicate that the DCBWSR can improve the sensitivity by about $1/\sqrt {2}$ , which is consistent with the theoretically calculated results. Compared with the conventional radiometers, the MCBWSR has the advantages of higher sensitivity, lower power consumption, and integration.