Riyanti, Kurnia Paranita Kartika (2026) Pengembangan Metode dalam Peningkatan Kinerja Antena Vivaldi untuk Aplikasi Ground Penetrating Radar (GPR). Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Ground Penetrating Radar (GPR) membutuhkan antena yang memiliki bandwidth lebar, gain memadai, pencocokan impedansi yang baik, pola radiasi terarah, dimensi kompak, serta struktur yang sederhana untuk mendukung sistem deteksi bawah permukaan yang portabel. Antena Vivaldi merupakan salah satu kandidat yang sesuai karena memiliki karakteristik ultra-wideband dan struktur planar. Namun, antena Vivaldi kompak masih memiliki beberapa tantangan, terutama pada peningkatan bandwidth, kestabilan gain, pencocokan impedansi, kesederhanaan pencatuan, dan sensitivitas terhadap objek dengan orientasi yang tidak diketahui. Oleh karena itu, penelitian ini bertujuan mengembangkan metode peningkatan kinerja antena Vivaldi untuk aplikasi GPR melalui beberapa tahapan pengembangan yang saling melengkapi. Metode penelitian dilakukan melalui perancangan antena Vivaldi dasar sebagai acuan, integrasi struktur artificial periodic structure (APS) dan artificial metamaterial lens structure (AMLs), evaluasi teknik pencatuan mikrostrip, mikrostrip melengkung, dan coplanar waveguide (CPW), optimasi pencatu CPW terintegrasi stub tunggal (single-stub), serta pengembangan antena Vivaldi berbasis dual apertur dengan stub tunggal (single-feed dual aperture). Setiap desain dievaluasi melalui simulasi, fabrikasi, pengukuran parameter antena, dan validasi awal pada skenario GPR menggunakan media pasir kering dan target logam terkubur. Parameter yang dianalisis meliputi S11, bandwidth, pencocokan impedansi, gain, efisiensi radiasi, half power beamwidth (HPBW), pola radiasi, distribusi arus permukaan, group delay, cross polarization discrimination (XPD), axial ratio, serta profil A-scan. Hasil penelitian menunjukkan bahwa integrasi APS dan AMLs mampu meningkatkan kinerja antena Vivaldi secara komplementer. APS berkontribusi terhadap pelebaran bandwidth, sedangkan AMLs berkontribusi terhadap peningkatan gain dan pengarahan radiasi. Konfigurasi VA+AMLs menghasilkan gain pengukuran tertinggi sebesar 7,2 dBi, sedangkan konfigurasi VA+APS+AMLs menghasilkan bandwidth pengukuran terbesar sebesar 3, 2 GHz dengan fractional bandwidth 82.1% dan HPBW sebesar 40◦ pada frekuensi 3 GHz. Pada tahap evaluasi pencatuan, pencatu CPW menghasilkan bandwidth terlebar pada rentang 1,1−4,7 GHz, sementara pencatu mikrostrip melengkung menghasilkan gain tertinggi sebesar 9,90 dB. Hasil ini menunjukkan bahwa CPW menjadi teknik pencatuan yang paling sesuai untuk penyederhanaan struktur antena Vivaldi broadband. Optimasi pencatu CPW terintegrasi single-stub menghasilkan peningkatan pencocokan impedansi dan performansi radiasi antena. Antena hasil optimasi bekerja pada rentang pengukuran 1,13−5 GHz, menghasilkan gain maksimum pengukuran sebesar 10,36 dBi, efisiensi radiasi sekitar 90,16%, dan return loss pengukuran sebesar −39,13 dB pada frekuensi 1,9 GHz. Validasi awal pada skenario GPR menunjukkan puncak respons A-scan pada kedalaman sekitar 37,7 cm, yang mendekati kedalaman aktual target sebesar 40 cm. Selanjutnya, antena Vivaldi berbasis single-feed dual-aperture mampu mendeteksi target logam pada orientasi 0◦, 45◦, dan 90◦ dengan estimasi kedalaman masing masing sebesar 29,3 cm, 27,9 cm, dan 28, cm terhadap kedalaman aktual 30 cm. Hasil tersebut membuktikan bahwa konfigurasi dual apertur dengan pencatu tunggal mampu meningkatkan kemampuan deteksi terhadap objek dengan berbagai orientasi tanpa memerlukan dua port atau dua antena terpisah. Secara keseluruhan, penelitian ini menghasilkan metode pengembangan antena Vivaldi yang kompak, sederhana, broadband, memiliki pencocokan impedansi yang baik, dan lebih adaptif terhadap variasi orientasi target bawah permukaan. Kontribusi utama penelitian ini terletak pada integrasi APS dan AMLs untuk peningkatan bandwidth dan gain, pemilihan CPW sebagai teknik penyederhanaan pencatuan, optimasi CPW terintegrasi stub untuk pencocokan impedansi, serta pengembangan dual apertur dengan pencatu tunggal untuk deteksi objek dengan berbagai orientasi pada aplikasi GPR.
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Ground Penetrating Radar (GPR) requires an antenna with wide bandwidth, sufficient gain, good impedance matching, directional radiation pattern,compact size, and simple structure to support portable subsurface detection systems. The Vivaldi antenna is a suitable candidate due to its ultra wideband characteristics and planar structure. However, compact Vivaldi antennas still face several challenges, particularly in bandwidth enhancement, gain stability, impedance matching, feeding simplicity, and sensitivity to targets with unknown orientations. Therefore, this research aims to develop performance enhancement methods for Vivaldi antennas in GPR applications through several complementary development stages. The research method was carried out by designing a basic Vivaldi antenna as a baseline, integrating artificial periodic structure (APS) and artificial metamaterial lens structure (AMLs), evaluating microstrip, curved microstrip, and coplanar waveguide (CPW) feeding techniques, optimizing a CPW feed integrated with a single stub, and developing a single-feed dual-aperture Vivaldi antenna. Each design was evaluated through simulation, fabrication, antenna measurement, and preliminary GPR validation using dry sand as the medium and buried metallic targets. The analyzed parameters included S11, bandwidth, impedance matching, gain, radiation efficiency, half power beamwidth (HPBW), radiation pattern, surface current distribution, group delay, cross polarization discrimination (XPD), axial ratio, and A-scan response. The results show that the integration of APS and AMLs improves the Vivaldi antenna (VA) performance in a complementary manner. APS contributes to bandwidth enhancement, while AMLs improves gain and radiation directivity. The VA+AMLs configuration achieves the highest measured gain of 7,2 dBi, whereas the VA+APS+AMLs configuration achieves the widest measured bandwidth of 3,2 GHz with a fractional bandwidth of 82,1% and an HPBW of 40◦ at 3GHz. Inthefeedingevaluation stage, the CPWfeed provides the widest bandwidth from 1,1 to 4,7 GHz, while the curved microstrip feed achieves the highest gain of 9,90 dB. These results indicate that CPW is the most suitable feeding technique for simplifying the structure of a broadband Vivaldi antenna. The optimization of the CPW feed integrated with a single stub improves the impedance matching and radiation performance of the antenna. The optimized antenna operates over the measured frequency range of 1,13−5 GHz, achieves a maximum measured gain of 10,36 dBi, radiation efficiency of approximately 90,16%, and a measured return loss of −39,13 dB at 1,9 GHz. Preliminary validation in a GPR scenario shows an A-scan response peak at a depth of approximately 37,7 cm, which is close to the actual target depth of 40 cm. Furthermore, the single-feed dual-aperture Vivaldi antenna successfully detects metallic targets at orientations of 0◦, 45◦, and 90◦, with estimated depths of 29,3 cm, 27,9 cm, and 28,7 cm, respectively, compared with the actual depth of 30 cm. These results confirm that the single-feed dual-aperture configuration improves target detection capability for arbitrary orientations without requiring two ports or two separate antennas. Overall, this research produces a compact, simple, broadband Vivaldi antenna development method with good impedance matching and improved adaptability to variations in subsurface target orientation. The main contributions of this research include the integration of APS and AMLs for
bandwidth and gain enhancement, the selection of CPW as a simplified feeding technique, the optimization of a CPW feed integrated with a stub for impedance matching, and the development of a single-feed dual-aperture configuration for arbitrary-oriented target detection in GPR applications.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | Artificial Metamaterial Lens, Artificial Periodic Structure, Antena Vivaldi, Coplanar Waveguide, Ground Penetrating Radar, single-feed dual-aperture, single stub. Artificial Metamaterial Lens, Artificial Periodic Structure, Coplanar Waveguide, Ground Penetrating Radar, single-feed dual-aperture, single stub, Vivaldi Antenna. |
| Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101 Telecommunication |
| Divisions: | Faculty of Intelligent Electrical and Informatics Technology (ELECTICS) > Electrical Engineering > 20001-(S3) PhD Thesis |
| Depositing User: | Kurnia Paranita Kartika Riyanti |
| Date Deposited: | 04 Aug 2026 03:56 |
| Last Modified: | 04 Aug 2026 03:56 |
| URI: | http://repository.its.ac.id/id/eprint/142874 |
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