## 4 Concluding Remarks  
The study aimed to design, develop, and evaluate a compact wideband circularly polarized phased array antenna capable of delivering optimal performance across the HF spectrum, where antenna dimensions impose limitations. The proposed antenna is intended for future use in a campaign to enhance existing HF spectral occupancy models with azimuthal measurements [35]. Significant emphasis was placed on two key design components: enhancing the low-noise amplifier (LNA) and linearizing the beamformer, both crucial for optimizing the performance of the wideband circularly polarized phased array antenna. Firstly, LNA neutralization played a pivotal role in mitigating the effects of internal parasitic capacitances within the cascade LNA. By incorporating negative feedback inductors, these parasitic capacitances have been eliminated, thereby enhancing the input impedance of the LNA. This improvement in the input impedance of the LNAs minimized signal losses and maximized the signal-to-noise ratio, which is particularly critical when the helical antennas are operating away from their resonant frequency. Such meticulous neutralization ensures that the helical antennas operate efficiently across the desired frequency range (15-30 MHz). The beamformer was essential for optimizing the operation of the phased array antenna. In order to maintain consistent phase difference across all operating frequencies, a compensation circuit was implemented for linearization. This circuit, comprising a variable phase 45\({}^{\circ}\) high-pass phase shifter and a fixed 90\({}^{\circ}\) hybrid, ensures stable phase relationships between the helical antennas. Additionally, the choice of a high-gain common-base amplifier topology at the output of the beamformer contributes to impedance matching between the array and the receiver and compensates for any losses caused by the mismatch of the helical antennas with the LNAs when the array operates at resonance. Furthermore, the front-to-back ratio, a crucial indicator of antenna directional performance, was found to be very satisfactory. Across both vertical and horizontal polarizations and within the frequency range of 15-30 MHz, the helical phased array antenna achieved an average front-to-back ratio exceeding 21 dB. Moreover, the axial ratio, which quantifies the polarization purity of the antenna, was measured at an impressive average of 2 dB. This indicates minimal deviation from ideal circular polarization, ensuring consistent and reliable signal reception across a wide range of azimuths. Such a low axial ratio is particularly crucial because it eliminates the need for the installation of a large and heavy circular polarization directional antenna to improve the signal-to-noise ratio (SNR) Finally, the antenna can be easily adapted to a square or circular array configuration, offering increased gain and a superior front-to-back ratio within highly constrained spaces where installing a large and heavy directional antenna would be impractical. Future research may focus on further optimization for specific operational scenarios within the 30 and 60 m bands.  
Conceptualization, A.C.; methodology, A.C.; formal analysis, C.K. and A.C.; investigation, A.C. and C.K.; data curation, C.K. and A.C.; writing--original draft preparation, A.C.; writing--review and editing, H.H. and S.N.; visualization, S.N.; supervision, H.H.; project administration, A.C.; funding acquisition, A.C., C.K. and S.N. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author/s.  
The authors declare no conflicts of interest.