Development of Array Triangular Microstrip Antenna for Circularly Polarized-Synthetic Aperture Radar

Circularly Polarized Synthetic Aperture Radar is an active remote sensing system that employs left- and right-handed circular polarization to enhance Earth observation capabilities. By operating in the C, S, and L frequency bands, Circularly Polarized Synthetic Aperture Radar enables the generation of axial ratio, ellipticity, and tilt angle images, thereby improving information extraction and overcoming conventional Synthetic Aperture Radar limitations such as high-power consumption, Faraday rotation sensitivity, backscatter distortion, and low target discrimination. In this study, we propose and investigate triangular microstrip array antennas as the core radiating elements for Circularly Polarized Synthetic Aperture Radar applications in the L-bands and C-bands. Designed for integration into Low Earth Orbit microsatellites and Unmanned Aerial Vehicles, these antennas provide notable advantages including compactness, light weight, conformability, cost-effectiveness, and ease of integration with other circuits. Numerical simulations, supported by partial experimental validation, confirm that the proposed antennas achieve adequate gain, axial ratio bandwidth, beamwidth, and efficiency. These results demonstrate that triangular microstrip arrays can fulfill the technical requirements for Circularly Polarized Synthetic Aperture Radar implementation on Low Earth Orbit and Unmanned Aerial Vehicle platforms, offering a promising solution for advanced, low-cost remote sensing systems.

Circularly polarized synthetic aperture radar; Low earth orbit; Microstrip array antenna; Remote sensing; Unmanned aerial vehicle

Amr, H. H., Mohamed, A. M., & Haythem, H. A. (2017). Hardware implementation of antenna array system for maximum SLL reduction. Engineering Science and Technology, an International Journal, 20(3), 965–972. https://doi.org/10.1016/j.jestch.2016.11.014

Ansoft Corporation. (2001). ANSOFT ensemble user guide manual (Ver. 8).

Asfour, R., Khamas, S., Ball, E., Ng, J., Huang, G., Allanic, R., Le Berre, D., Quendo, C., Leuliet, A., & Merlet, T. (2024). On-chip circularly polarized circular loop antennas utilizing 4H-SiC and GaAs substrates in the Q/V band. Sensors, 24(2), 321. https://doi.org/10.3390/s24020321

Baharuddin, M., Wissan, V., Sri Sumantyo, J. T., & Kuze, H. (2009). Equilateral triangular microstrip antenna for circularly-polarized synthetic aperture radar. Progress in Electromagnetics Research C, 8, 107–120. https://doi.org/10.2528/PIERC09052202

Basari, Sri Sumantyo, J. T., Takahashi, M., & Ito, K. (2006). Circularly polarized triangular microstrip array antenna using single-fed proximity-coupled for mobile satellite communications applications. Proceeding IJJSS 2006.

Beegum, S., Joseph, M., Joyas, S., Jayakumar, M., & Girija, J. (2024). Dual circularly polarized broadband microstrip antenna array for space re-entry vehicle applications in S band. ICTACT Journal on Communication Technology, 15(3), 3229–3235. https://doi.org/10.21917/ijct.2024.0481

Chang, K. (2005). Encyclopedia of RF and microwave engineering. John Wiley & Sons Inc.

Chen, Q., Yang, J., He, C., Zhang, D., Huang, S., Wang, M., Yu, F., & Dai, G. (2024). Wideband circularly polarization and high-gain of a slot patch array antenna realized by a hybrid metasurface. Sensors, 24(11), 3510. https://doi.org/10.3390/s24113510

CST AG. (2016). CST STUDIO SUITE 2016: Microwave–radio frequency–optical [Copyright © 1998–2016 CST AG].

Delaune, D., Sri Sumantyo, J. T., Takahashi, M., & Ito, K. (2006). Circularly polarized rounded-off triangular microstrip line array antenna. IEICE Transactions on Communications, E89-B(4), 1372–1381.

Delfini, D., Tervo, N., Javed, M., Leinonen, M., & Pärssinen, A. (2024). Tapering impact on the spatial and frequency responses of broadband asymmetrically routed phased arrays. 2024 18th European Conference on Antennas and Propagation (EuCAP), 1–5. https://doi.org/10.23919/EuCAP60739.2024.10501642

Deshmukh, A., & Ray, K. (2020). Circularly polarized designs of modified isosceles triangular microstrip antennas. Engineering Reports, 2(10). https://doi.org/10.1002/eng2.12250

Deshmukh, A. A., & Chavali, V. A. P. (2026). Reconfigurable designs of U-slot cut microstrip antennas for dual band circularly polarized response. Progress In Electromagnetics Research B, 116, 1–18. https://doi.org/10.2528/PIERB25072205

Ding, Z., Xu, M., Li, X., Tao, S., Wang, H., & Zhang, X. (2023). Design of wideband circularly polarized metasurface antenna using characteristic mode analysis. Microwave and Optical Technology Letters, 65(6).

Dong, G., Lv, S., & Zhang, Y. (2025). A Ku-band circularly polarized array antenna based on vertical virtual ground. Electronics, 14(23), 4691. https://doi.org/10.3390/electronics14234691

Du, B., & Yung, E. K. N. (2002). Single-feed TM21 mode circular patch antenna with circular polarization. Microwave and Optical Technology Letters, 33(3), 154–156. https://doi.org/10.1002/mop.10262

Grebennikov, A. (2011). RF and microwave transmitter design. John Wiley & Sons Inc.

Horng, T. S., & Nicholas G. Alexopoulos (1993). Corporate feed design for microstrip arrays. IEEE Transactions on Antennas and Propagation, 41(12), 1615–1624. https://doi.org/10.1109/8.273304 

Ishihara, H., Yamamoto, A., & Ogawa, K. (2002). A simple model for calculating the radiation patterns of antennas mounted on a vehicle roof. Interim International Symposium on Antenna and Propagation, 548–551.

Jiao, Y., Zhang, F., Liu, X., Huang, Z., & Yuan, J. (2025). C-SAR/02 satellite polarimetric calibration and validation based on active radar calibrators. Remote Sensing, 17(2), 282. https://doi.org/10.3390/rs17020282

Kashihara, H., Sumantyo, J. T. S., Izumi, Y., Ito, K., Gao, S., & Namba, K. (2023). X-band microstrip array antenna for UAV onboard full circularly polarized synthetic aperture radar. IEEE Transactions on Antennas and Propagation, 71, 1943–1948.

Kedze, K., Wang, H., Park, Y., & Park, I. (2022). Substrate dielectric constant effects on the performances of a metasurface-based circularly polarized microstrip patch antenna. International Journal of Antennas and Propagation, 2022, 3026677. https://doi.org/10.1155/2022/3026677

Koo, V. C., Chan, Y. K., Vetharatnam, G., Chua, M. Y., Lim, C. H., Lim, C. S., Thum, C. C., Lim, T. S., Ahmad, Z., Mahmood, K. A., Shahid, M. H., Ang, C. Y., Tan, W. Q., Tan, P. N., Yee, K. S., Cheaw, W. G., Boey, H. S., Choo, A. L., & Sew, B. C. (2012). A new unmanned aerial vehicle synthetic aperture radar for environmental monitoring. Progress in Electromagnetics Research, 122, 245–268. https://doi.org/10.2528/PIER11092604

Li, M., Sun, Z., Tang, M.-C., & Zhu, L. (2024). Broadband circularly polarized microstrip antenna with customized tilted beam based on index-modulated folded split ring resonator. IEEE Transactions on Antennas and Propagation, 72(3), 2831–2836. https://doi.org/10.1109/TAP.2024.3353346

Li, Z., Liu, Y., Zhao, M., Zong, W., & He, S. (2025). A wideband circularly polarized metasurface antenna with high gain using characteristic mode analysis. Electronics, 14(14), 2818. https://doi.org/10.3390/electronics14142818

Liu, S., Yang, L., & Wu, X. (2022). A low-profile wideband circularly polarized metasurface antenna based on characteristic mode theory. Applied Computational Electromagnetics Society Journal, 37(11), 1110–1117. https://doi.org/10.13052/2022.ACES.J.371101

Morini, A., Rozzi, T., Farina, M., & Angeletti, P. (2024). Scattering matrix of a reciprocal and lossless, three-port power divider. IEEE Microwave and Wireless Technology Letters, 34(11), 1223–1226. https://doi.org/10.1109/LMWT.2024.3460168

Mujahidin, I., Pramono, S. H., & Muslim, A. (2018). 5.5 GHz directional antenna with 90 degree phase difference output. Proceedings of the 2018 Electrical Power, Electronics, Communications, Controls, and Informatics Seminar (EECCIS), 224–228. https://doi.org/10.1109/EECCIS.2018.8692872

Nasimuddin, & Karu P. Esselle (2007). High-gain wideband circularly polarized stacked microstrip antennas with single microstrip feeds and short horns. Proc. IEEE Antennas and Propagation Society Int. Symp., 737–740.

Park, M. Y., Kim, J. H., Yi, S. H., Lim, W., Yang, Y., & Hwang, K. C. (2024). Design of series-fed circularly polarized beam-tilted antenna for microwave power transmission in UAV application. Applied Sciences, 14, 3490. https://doi.org/10.3390/app14083490

David M. Pozar (2005). Microwave engineering (3rd ed.). John Wiley & Sons Inc.

Purnomo, M. F. E., Basari, & Sri Sumantyo, J. T. (2014). Circularly polarized stack-patch microstrip array antenna for mobile satellite communications. Proceedings IJJSS 2014, Theme Antenna and Microwave, 269–275.

Purnomo, M. F. E., & Kitagawa, A. (2017). Developing basic configuration of triangle array antenna for circularly polarized-synthetic aperture radar sensor application. Proceedings of IEEE 2017 International Conference on Radar, Antenna, Microwave, Electronics, and Telecommunications (ICRAMET 2017), 112–117.

Purnomo, M. F. E., & Kitagawa, A. (2018). Analysis performance of triangle microstrip antenna for basic construction of circularly polarized-synthetic aperture radar application. Jurnal Teknologi, 80(2). https://doi.org/10.11113/jt.v80.11119

Purnomo, M. F. E., Kusumasari, V., Ambarwati, R., Supriana, E., Yuwono, R., Adi, P. D. P., & Kitagawa, A. (2021). Development of patch stack antenna for CP-SAR sensor. Bulletin of Electrical Engineering and Informatics, 10(1), 200–207. https://doi.org/10.11591/eei.v10i1.2672

Purnomo, M. F. E., Kusumasari, V., Supriana, E., Ambarwati, R., & Kitagawa, A. (2020). Development of triangular array eight patch antennas for circularly-polarized synthetic aperture radar sensor. TELKOMNIKA (Telecommunication, Computing, Electronics and Control), 18(2), 631–639. https://doi.org/10.12928/TELKOMNIKA.v18i2.14759

Purnomo, M. F. E., Kusumasari, V., Suyono, H., Hasanah, R. N., & Kitagawa, A. (2019). The four patches of triangular microstrip antennas as configuration of CP-SAR. Proceedings of the 2019 2nd International Conference on Electronics and Electrical Engineering Technology (EEET 2019), 55–61. https://doi.org/10.1145/3362752.3362768

Purnomo, M. F. E., Pramono, S. H., Pamungkas, M. A., & Taufik. (2015). Study of the effect of air-gap on array microstrip antenna performances for mobile satellite communications [ISSN 1819-6608]. ARPN Journal of Engineering and Applied Sciences, 10(20).

Purnomo, M. F. E., & Sri Sumantyo, J. T. (2011). Design circularly polarized of equilateral triangular hole antenna for SAR (synthetic aperture radar) [ISSN 0913-5685]. IEICE Technical Report, 111(239).

Reis, S., Silva, F., Albuquerque, D., & Pinho, P. (2025). General overview of antennas for unmanned aerial vehicles: A review. Electronics, 14, 3205. https://doi.org/10.3390/electronics14163205

Sahana, K., & Sowmya, K. (2024). Planar rectangular microstrip patch antenna array with corporate-feed network for gain enhancement. International Journal for Research in Applied Science and Engineering Technology, 12(8), 108–112. https://doi.org/10.22214/ijraset.2024.63863

Sarkar, T. K., Djordjevic, A. R., & Kolundzija, B. M. (2000). Method of moments applied to antennas. MTT ETF BGAC.

Smith, J. A., & Lee, R. B. (2023). A wideband stacked microstrip patch antenna for telemetry applications. International Journal of Antennas and Propagation, 2023, 604303.

Tanaka, T., Houzen, T., Takahashi, M., & Ito, K. (2006). Circularly polarized printed antenna combining slots and patch. IEICE Transaction Communications, E89-B.

Tiwari, A., Yilmaz, M. Y., Soni, G. K., & Yadav, D. (2025). Design and development of multi-band multi-mode frequency reconfigurable CPW-fed antenna for 5G wireless communication. International Journal of Reconfigurable and Embedded Systems (IJRES), 14 (2), 328–338. https://doi.org/10.11591/ijres.v14.i2.pp328-338

Tran-Huy, H., & Pham-Danh, T. (2025). Low-profile high-gain circularly polarized antenna using high-order mode microstrip patch. Heliyon, 11 (9), e42863.

Urata, K. N., Sumantyo, J. T. S., Perissin, D., & Viscor, T. (2019). A compact C-band CP-SAR microsatellite antenna for earth observation. Acta Astronautica, 159, 517–526.

Wahyudi, Setyadewi, I. T., Sakti, M. A. K., Prabowo, Y., Hadiyanti, D. M., Rahayu, N., Muzayadah, N. L., Wahyudi, A. H., Guno, Y., Praludi, T., Santosa, C. E., & Sri Sumantyo, J. T. (2025). Analysis of unmanned aerial vehicle airframe materials on circularly polarized antenna radiation characteristics. Bulletin of Electrical Engineering and Informatics, 14 (4), 2649–2661. https://doi.org/10.11591/eei.v14i4.8010

Wong, K. L. (2002). Compact and broadband microstrip antennas. Wiley.

Yohandri, Y., Wissan, V., Firmansyah, I., Rizki Akbar, P., Sri Sumantyo, J. T., & Kuze, H. (2011). Development of circularly polarized array antenna for synthetic aperture radar sensor installed on UAV. Progress in Electromagnetics Research C, 19, 119–133. https://doi.org/10.2528/PIERC10121708

Zhang, Y., Wang, Y., & Li, X. (2025). Low-profile high-gain circularly polarized antenna using high-order mode. Heliyon, 11 (3), e01244.