**1. Introduction**

Electromagnetic field theory is essential in designing and analyzing the shape and size of the antenna. In general, the electromagnetic fields generated depend on the distance of the source access and terrain. The further course of electromagnetic fields affects the spread process from the transmitter to the receiver, weakening the signals. Therefore, the required antenna design with specific dimensions, such as a high gain value and significant directivity with return loss is minimal. Various studies have been conducted on microstrip antenna. In this research, a new type of antenna is design with an nxn array bi-ellipse microstrip. This is an antenna type microstrip with various characteristics, including a thin cross-section, lightweight mass, simple to make, and can be easily integrated with Microwave Integrated Circuits (MICs) made in multifrequency.

In this research, the nxn array bi-ellipse microstrip antenna is developed in multiband frequency for satellite communication. The optimization of the width feeding stripline is meant to enhance the performance of the antenna. The proposed nxn array bi-ellipse microstrip antenna operates in multiband frequency. It targets the multiband frequency, reflection coefficient less than 1, Voltage Standing Wave Ratio (VSWR) less than 2, and gain more than 5 dB.

Numerous studies have been conducted on a wide variety of designs and shapes of microstrip antenna by providing slots, patches, and adding several arrays. The use of a slot can increase bandwidth. This is because smaller widths increase the bandwidth, number of arrays, and antenna gain [1–3]. According to previous studies, the antenna's array is used to direct radiated power toward a desired angular sector. The number, geometrical arrangement, relative amplitudes, and phases of the array element depend on the angular pattern that needs to be achieved.

Other research used a flexible, compact antenna array operating at a frequency of 3.2-13GHz, which covers the standard Ultra-Wide Band (UWB). The design aimed to integrate Multiple Input Multiple Output (MIMO) based flexible electronics for Internet of Things (IoT) applications. The proposed antenna is printed on a single side of a 50.8 μm Kapton Polyimide substrate, which consists of two half-elliptical shaped radiating elements fed by two Coplanar Waveguide (CPW) structures. The simulated and measured results showed that the proposed antenna array achieves a broad impedance bandwidth with reasonable isolation performance of *S*<sup>12</sup> < -23 dB [4]. Furthermore, it exhibits a low susceptibility to performance degradation due to the effect of bending. The system's isolation performance, along with its flexible and thin profile, suggests that the proposed antenna is suitable for integration within the flexible Internet of Things (IoT) and wireless systems. The research conducted by indicates good performance in antenna design. However, the application is limited to the wireless communication system. A related study on a novel S-band right-handed circularly polarized (RHCP) slot antenna for supporting the communication system of GAIA II/LAPAN-Chibasat was conducted [5, 6]. This satellite implemented the Lband Circularly Polarized Synthetic Aperture Radar (CP-SAR) sensor, with an X-band antenna employed for mission data downlink and S-band antenna for the command and telemetry. The S-band antenna is printed on the substrate with a relative permittivity of 2.17 and a thickness of 1.6 mm. A crescent-shaped slot is placed on the ground plane to strengthen the radiation on the edge of the feed-line. Furthermore, a parasitic strip rectangular-shaped is added on the ground plane to enhance the antenna. The truncation technique is employed to increase the axial bandwidth ratio (ARBW) and the gain [4, 7, 8]. The total dimension of the antenna is 170 mm 170 mm. This research's weakness is the bandwidth produced, which is less than 3 dB and return loss below 10 dB. Also, the substrate used in designing the antenna is challenging to determine. The research shows the design and development of an X-band microstrip patch planar array antenna with high gain and low sidelobes. The radiating patches are fed using a thin, grounded substrate microstrip distribution network with a common geometry. All the 512 array elements are fed using a direct feeding technique by utilizing a thin copper wire soldered at the patch and feed network ends. The array operates in the 10.1-10.5GHz frequency band with a 2:1 VSWR. Furthermore, the high gains were above 30.5dBi with sidelobe levels better than -23 dB in both planes. The antenna application was found in the medium-range radar systems operating at Xband frequency [9, 10]. This research also acts as references used to increase the gain of the antenna and other applications designed within the radar band frequency range. The bi-ellipse microstrip antenna array variants are designed to optimize antenna characteristics capable of supporting the radar application system.
