Objektif utama keseluruhan tesis adalah untuk mereka bentuk empat jenis antena yang beroperasi dalam julat frekuensi jalur lebar dan menyelidik perbezaan sifat-sifat setiap antena serta membezakan antara antena pelbagai arah dan antena satu arah. Antara parameter yang diselidik adalah dimensi bagi setiap antena. Perbezaan nilai panjang dan lebar garis strip yang dicetak di atas papan litar bercetak FR-4 mempunyai kesan yg besar terhadap kehilangan balikan, lebar jalur dan corak radiasi setiap antena. Kesemua rekabentuk antena yang dikemukakan direka dan disimulasi menggunakan perisian computer CST Microwave Studio dan Agilent ADS. Dengan menggunakan CST, keputusan simulasi boleh dilihat menerusi pandangan 3D. Rekabentuk yang telah dioptimumkan dan diubah untuk mendapatkan keputusan simulasi terbaik akan difabrikasi dan diuji untuk melihat sama ada ia memberi keputusan yang sama dengan keputusan simulasi. Berdasarkan keputusan simulasi, kesemua rekabentuk beroperasi di dalam julat frekuensi yang lebar dan mempunyai kehilangan balikan yang lebih rendah dari garis rujukan -10 dB. Daripada keputusan simulasi jarak jauh, dua dari antena memancarkan gelombang elektromagnet dengan ciri-ciri antena satu arah manakala dua lagi antena memancarkan gelombang elektromagnet dengan ciri-ciri antena satu arah. Ini boleh diperhatikan dengan memerhati corak radiasi 3D dengan menggunakan perisian komputer. Terdapat sedikit perbezaan antara keputusan simulasi dan fabrikasi. Terdapat banyak faktor yang menyumbang kepada perbezaan nilai keputusan dibincangkan di dalam tesis. Secara keseluruhannya, keputusan eksperimen membuktikan bahawa semua rekabentuk antena beroperasi dalam julat frekuensi lebar.
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The main objective of this thesis is to design four types of wideband antenna which are monopole, dipole, yagi, and log-periodic antennas and to study the difference and characteristic for each of the antenna as well as to differentiate between an omnidirectional and directional antenna type. Among the parameters that are being researched are the dimensions of each of the antenna. Different values of length and width of the stripline printed on the FR-4 printed circuit board has a major effect on the antenna return loss, bandwidth and radiation pattern. All of the proposed antenna were designed and simulated by using the CST Microwave Studio and Agilent ADS software. By using CST, the simulated results can be viewed through 3D perspective. The design that has been already optimized and altered to get the best simulation results were fabricated and tested to see whether it shows the same results as simulated. Based on the simulation result, it can be concluded that all of the designs were operating in wideband frequency range and has a return loss lower than the -10 dB reference line. From the far-field simulated results, monopole and dipole antennas are radiating EM waves with omnidirectional characteristic while the yagi and log-periodic antennas are radiating EM waves with directional characteristic. This can be seen by observing the 3D radiation pattern by using software. There were slight difference between the fabricated results and the simulated results. Factors that can contribute to the mentioned mismatch of result were discussed thoroughly in this thesis. Overall, the results of the experiment proved that all of the designed antennas were operating in a wideband frequency.
Wideband antennas design and analysis Kaharul Afandi Kahar_E3_2010_875003565_00003084255_NI