The h Function in 1-D Mirrored Aperture Synthesis Considering Practical Factors

The mirrored aperture synthesis (MAS) was proposed to improve the spatial resolution in passive microwave remote sensing. In MAS, the elements in the (H matrix) are the sampled values of the h function. In this article, the h function considering practical factors is derived. These practical factors include the normalized antenna pattern, the reflector reflectivity, the reflector length, and the distance between the array and the scene. The normalized antenna pattern modulates the received signals. The reflector reflectivity affects amplitudes of the reflected signals. The reflector length determines whether the reflected signals can be received. The distance between the array and the scene influences the incident angles of the signals from the same point source in the scene. The distance also influences the path differences between signals. The formulas and related analysis are verified through the numerical simulations and experiments.

I. Introduction

In passive microwave remote sensing, compared with aperture synthesis (AS), mirrored aperture synthesis (MAS) has higher spatial resolution [1], [2]; therefore, MAS has an application prospect for earth observation in geostationary orbit [3]. The existing methods for the brightness temperature (BT) reconstruction in MAS include the inverse cosine transform method [1], the impulse matrix method [4], [5], and the method with deep convolutional neural network (MAS-CNN) [6]. The impulse matrix method and MAS-CNN utilize the spatial impulse response matrix ( matrix) to establish a mapping relationship between BT and correlation of antenna outputs. Based on this mapping relationship, BT can be reconstructed. The quality of the matrix directly affects the quality of the BT reconstructed by these two methods. Therefore, the in-depth analysis of the matrix is crucial for improving BT reconstruction quality.