A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achie...A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.展开更多
The attractiveness of flying several SAR （synthetic aperture radar） satellites in a semi-active configuration has been proposed by several studies. The closest implementation of such a mission scenario is exemplifie...The attractiveness of flying several SAR （synthetic aperture radar） satellites in a semi-active configuration has been proposed by several studies. The closest implementation of such a mission scenario is exemplified by the current Terra SAR-X and Tandem-X mission, where both spacecraft are identical monostatic platforms capable of operating in various modes. The bistatic operation mode of the Tandem-X mission is a basic form of the semi-active multi-static operation mode where one satellite serves as a transmitter while the other records the scattered signals simultaneously. The use of a typical monostatic SAR spacecraft operating in-tandem with several receiver only spacecraft is a semi-active mode of operation. This paper examines the capabilities of implementing a constellation of S-band spaceborne SAR platform for alongtrack interferometry over the equatorial region for velocity measurement with particular focus on ship detection. The orbit for the mission is an inclined circular low Earth orbit, which ensures high revisit time, quick coverage and high data throughput. The pendulum configuration is adopted to maintain the relative distance between successive SAR platforms. The conditions and constraints necessary to achieve the orbit geometry required to conduct alongtrack interferometry are defined. The alongtrack separation between platforms necessary to measure specified ship velocity is also discussed. Finally an error budget estimate of the measure radial velocity is provided.展开更多
文摘A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.
文摘The attractiveness of flying several SAR （synthetic aperture radar） satellites in a semi-active configuration has been proposed by several studies. The closest implementation of such a mission scenario is exemplified by the current Terra SAR-X and Tandem-X mission, where both spacecraft are identical monostatic platforms capable of operating in various modes. The bistatic operation mode of the Tandem-X mission is a basic form of the semi-active multi-static operation mode where one satellite serves as a transmitter while the other records the scattered signals simultaneously. The use of a typical monostatic SAR spacecraft operating in-tandem with several receiver only spacecraft is a semi-active mode of operation. This paper examines the capabilities of implementing a constellation of S-band spaceborne SAR platform for alongtrack interferometry over the equatorial region for velocity measurement with particular focus on ship detection. The orbit for the mission is an inclined circular low Earth orbit, which ensures high revisit time, quick coverage and high data throughput. The pendulum configuration is adopted to maintain the relative distance between successive SAR platforms. The conditions and constraints necessary to achieve the orbit geometry required to conduct alongtrack interferometry are defined. The alongtrack separation between platforms necessary to measure specified ship velocity is also discussed. Finally an error budget estimate of the measure radial velocity is provided.
