5:15 PM - 7:15 PM
[PEM16-P02] Development of the analog signal receiver system for next-generation solar wind observation system
Keywords:solar wind, coronal mass ejection, interplanetary scintillation, phased array
The Institute of Space-Earth Environmental Research (ISEE), Nagoya University is currently developing the next generation of solar wind observing system. This project aims to clarify the physical mechanisms of the solar wind and improve space weather forecasting. This observation system uses two new technologies: a 2D phased array and digital beamforming. However, the required specifications for the analog signal receiver system (the RF system) between the antenna system and the digital backend, have not yet been determined. The RF system faces two primary challenges. First, the details of the signal combination system need to be defined. A sub-array is a unit of 16 dipole antennas and 1024 sub-arrays constitute the 2D phased array. The analog signal synthesis system combines the signals from these 16 antennas. However, the system is installed before the low-noise amplifier and significantly affects the noise performance of the overall receiver system. Therefore, minimizing the noise figure of the signal synthesis system is essential. Second, input and output specifications of the RF system need to be defined. It is crucial to clearly define the power requirements for the input signals from the antenna system and the output signals to the digital backend. This research aims to develop an optimized RF system for next-generation solar wind observation.
First, we estimated the required specifications for the RF system in terms of receiver noise temperature and gain. Under the conditions of a frequency bandwidth of 20 MHz and an integration time of 20 msec, we designed the RF system to detect the minimum flux density of 0.3 Jy. Two parameters were required to calculate the receiver noise temperature: the effective aperture area and the antenna noise temperature. The effective aperture area was estimated using electromagnetic field simulations, and the antenna noise temperature was estimated using the Global Sky Model 2016, which models the distribution of galactic radio emission. The estimated effective aperture area was 2.8 × 103 m2, and the antenna noise temperature was 78 K. Consequently, the required receiver noise temperature was found to be less than 97 K. The gain requirement was determined based on the received power of the sub-array and the dynamic range of the digital backend. As a result, the required gain was found to be more than 46 dB. Next, we proposed an RF receiver model. To achieve low-cost mass production, we combined modules with performance comparable to that of commercially available components. We developed a receiver system with minimal insertion loss and a low-noise amplification system that achieves over 50 dB of gain. This RF model has a gain of 68 dB and a receiver noise temperature of 128 K. The receiver system at the front end resulted in an unavoidable receiver noise temperature. Therefore, achieving the target noise temperature of 97 K will to be a challenge. Finally, we constructed a prototype RF system using available modules as the proposed model and we conducted evaluation measurements. Through the Y-factor method, the prototype showed a gain of 83 dB and a receiver noise temperature of 302 K. Although the prototype did not meet the required specifications, it was found that the coaxial cables had an insertion loss of 1.4 dB, corresponding to a noise temperature of 110 K. By replacing the coaxial cable with LMR400 cable, which is used in the Square Kilometer Array project, an the noise temperature is expected to be improved more than 80 K.
In the future, we should conduct field experiments and give feedback to required specifications to realize a more optimized RF system.
First, we estimated the required specifications for the RF system in terms of receiver noise temperature and gain. Under the conditions of a frequency bandwidth of 20 MHz and an integration time of 20 msec, we designed the RF system to detect the minimum flux density of 0.3 Jy. Two parameters were required to calculate the receiver noise temperature: the effective aperture area and the antenna noise temperature. The effective aperture area was estimated using electromagnetic field simulations, and the antenna noise temperature was estimated using the Global Sky Model 2016, which models the distribution of galactic radio emission. The estimated effective aperture area was 2.8 × 103 m2, and the antenna noise temperature was 78 K. Consequently, the required receiver noise temperature was found to be less than 97 K. The gain requirement was determined based on the received power of the sub-array and the dynamic range of the digital backend. As a result, the required gain was found to be more than 46 dB. Next, we proposed an RF receiver model. To achieve low-cost mass production, we combined modules with performance comparable to that of commercially available components. We developed a receiver system with minimal insertion loss and a low-noise amplification system that achieves over 50 dB of gain. This RF model has a gain of 68 dB and a receiver noise temperature of 128 K. The receiver system at the front end resulted in an unavoidable receiver noise temperature. Therefore, achieving the target noise temperature of 97 K will to be a challenge. Finally, we constructed a prototype RF system using available modules as the proposed model and we conducted evaluation measurements. Through the Y-factor method, the prototype showed a gain of 83 dB and a receiver noise temperature of 302 K. Although the prototype did not meet the required specifications, it was found that the coaxial cables had an insertion loss of 1.4 dB, corresponding to a noise temperature of 110 K. By replacing the coaxial cable with LMR400 cable, which is used in the Square Kilometer Array project, an the noise temperature is expected to be improved more than 80 K.
In the future, we should conduct field experiments and give feedback to required specifications to realize a more optimized RF system.