## 1 Introduction  
In recent decades, the number of human-made objects orbiting the Earth has grown significantly. This includes operational satellites, inactive spacecraft, launch vehicles, and debris from satellite collisions or breakups [1, 2]. Space Situational Awareness (SSA) aims to provide accurate and timely information about space traffic to prevent collisions and mitigate potential threats [3]. To support these objectives, recent efforts have focused on the development of advanced sensors for detecting, identifying, and characterizing space objects using data collected from both terrestrial and space-based observation systems [4]. The goal is to establish a comprehensive network of SSA sensors for the all-orbit identification and characterization of space assets. Extensive studies have shown that most space debris, operational satellites, and spacecraft are in Low Earth Orbit (LEO) [5]. Therefore, emphasis is placed on the sensitive detection of these objects and the accurate estimation of their position, velocity, and trajectory, as these capabilities are critical for enhancing safety in the near-Earth environment. The continuous and precise monitoring of such debris is also essential to maintain stable orbital positioning and to ensure the long-term sustainability of space operations [2; 6]. To address these challenges, bistatic radar systems have proven to be essential in space surveillance and debris detection, owing to their ability to cover extensive distances and wide spatial areas [7]. Their configuration allows for the detection of objects that may be difficult to track by using monostatic systems, especially those with low radar cross-sections, such as small debris fragments or stealth satellites [8]. Moreover, bistatic radars can operate over greater ranges and from diverse geometrical angles, enhancing their effectiveness in tracking fast-moving objects in Earth orbit [9]. These advantages, however, come with the need for increased sensitivity and precision, leading to more stringent performance requirements for the antennas employed in such systems [10]. In this context, Circularly Polarized (CP) antennas offer significant benefits, as they reduce the need for precise alignment between transmitting and receiving units, thereby mitigating errors caused by multipath propagation [11]. CP microstrip patch antennas are widely adopted in satellite communication systems due to their advantageous electromagnetic characteristics and structural simplicity [12]. Their planar structure allows easy integration into electronic systems without requiring complex fabrication steps, making them ideal for mass deployment using standard Printed Circuit Board (PCB) technologies [13]. Additionally, their design can be easily customized to meet specific frequency requirements and performance criteria, offering the flexibility needed to support a wide range of applications with varying specifications [14]. A fundamental limitation of microstrip patch antennas is their inherently low gain, which frequently necessitates the use of array configurations to satisfy performance requirements [15]. Antenna arrays are typically realized by spatially distributing individual radiating elements in specific geometric arrangements, such as linear, rectangular, or circular layouts. These configurations enhance radiation properties, particularly in terms of gain and directivity, by exploiting constructive and destructive interference patterns of the radiated electromagnetic fields [16]. The resultant radiation pattern is the vector sum of the individual electric fields of the array elements. For efficient directional radiation, constructive interference must occur in the desired direction, while destructive interference is required in undesired directions to minimize side lobes. Among the different types of antenna arrays, phased arrays provide the capability of electronic beam steering, achieved by manipulating the amplitude and phase of the individual element excitations.