ABSTRAKSI: Filter adalah suatu perangkat yang digunakan untuk menyaring daerah frekuensi kerja dengan meloloskan frekuensi yang diinginkan (pass band) dan meredam frekuensi yang tidak diinginkan (stop band). Berdasarkan daerah frekuensi yang diloloskan, filter dapat dibagi menjadi beberapa jenis yaitu: LPF (Low Pass Filter), BPF (Band Pass Filter), HPF (High Pass Filter), dan BSF (Band Stop Filter).
Proyek Akhir ini bertujuan untuk merancang dan merealisasikan sebuah filter jenis BPF (Bandpass Filter) untuk Transmitter Radar Pengawas Pantai. Filter yang dibuat berupa Defected Ground Structure (DGS) Hairpin bandpass filters microstrip. Saluran mikrostrip adalah saluran transmisi yang terdiri dari strip konduktor (patch) dan ground plane yang dipisahkan oleh substrat dengan karakteristik bahan tertentu. Patch dan ground plane yang digunakan berasal dari lapisan tembaga dengan tebal 0.035 mm, dengan substrat Duroid Rogers 4003 yang mempunyai εr = 3.38 dan tinggi substrat 1.575 mm. Bentuk respon frekuensi BPF DGS Hairpin dirancang berdasarkan respon selective filters with single pair of transmission zeros.
Untuk mendapatkan informasi tentang kinerja dan karakteristik prototype yang telah dibuat, maka filter diuji dengan menggunakan Network Analyzer. Adapun parameter yang diuji dari prototipe BPF ini adalah respon frekuensi filter, Bandwidth, Insertion Loss, perubahan fasa, Return Loss, Standing Wave Ratio, dan impedansi terminal. Adapun hasil pengukuran dari karakteristik BPF ini adalah: frekuensi tengah 9400 MHz dengan bandwidth 292 MHz (pada 10.731 dB), insertion loss 7.579 dB, VSWR ≤ 1.5 pada input dan ≥ 1.5 pada output, perubahan fasa terhadap frekuensi konstan, dan impedansi terminal 44.494 + j3.109 (input) dan 62.234 – j51.093 (output). Dari hasil pengukuran dapat diketahui bahwa BPF yang dibuat masih terlalu landai, sehingga performansi filter masih belum sesuai dengan yang diharapkan.Kata Kunci : Band Pass Filter DGS Hairpin, Mikrostrip, Standing Wave Ratio, Insertion Loss, Return Loss, Network Analyzer.ABSTRACT: Filter is a device used to filter the operating frequency with the desired frequency pass (pass band) and damp out unwanted frequencies (stop band). Based on the frequency region passed, filters can be divided into several types, namely: LPF (Low Pass Filter), BPF (Band Pass Filter), HPF (High Pass Filter), and BSF (Band Stop Filter).
This Final Project was aimed for designing and realizing a BPF (band pass filter) for Coastal Surveillance Radar transmitter. The filter made was combined bandpass filters microstripe. Microstripe channel is a transmission channel that consists of conductor stripe (patch) and ground plane that is separated by substrate with certain material characteristic. Patch and ground plane used was made from copper with 0.035 mm thick, with Duroid Rogers 4003 substrate that has εr = 3.38 and 1.575 mm height. The shape of DGS Hairpin BPF frequency response was designed based on selective filters with single pair of transmission zeros.
To get information about the activity and characteristic of the prototype that has been made, this filter was tested using Network Analyzer. The parameter tested from this BPF prototype are Frequency response, Bandwidth, Insertion Loss,the change of phase, Return Loss, Standing Wave Ratio, and terminal impedance. The measurement results from BPF characteristic are: center frequency 9400 MHz with bandwidth 292 MHz (at 10.731 dB), insertion loss 7.579 dB, VSWR 1.5 at input and ≥ 1.5 at output, the change of phase with frequency is constant, and terminal impedance 44.494 + j3.109 (input) dan 62.234 – j51.093 (output). From the measurement results it can be seen that the BPF is made is too sloped, so the performance of the filter is still not as expected.Keyword: Band Pass Filter DGS Hairpin, Mikrostrip, Standing Wave Ratio, Insertion Loss, Return Loss, Network Analyzer.