RANCANG BANGUN ANTENA CATURCULA OMNIDIREKTIONAL CHEBYSEV – KAWAT KEMBAR 0,3 – 3,0 GHZ, IMPEDANSI TERMINAL 50 Ω, VSWR ≤ 1,5, GAIN ≥ 2,14 dBi, TANPA FERIT CATUAN MONOPOL

ABSTRAKSI: Antena Caturcula chebyshev – omnidireksional monopol 0,3 GHz -3,0 GHz ini dirancang bangun dengan dua tujuan: 1. Untuk menyediakan prototipe antena unidireksional berpita sangat lebar, supaya dapat digunakan oleh beberapa operator secara bergotong – royong, untuk menghemat menara dan lahannya 2. Untuk membuktikan hipotesis dari pembimbing 1 bahwa antena adalah pemadan impedansi antara ruang propagasi dengan saluran radio.Spesifikasi yang harus dipenuhi adalah: frekuensi kerja 0,3 GHz – 3,0 GHz dalam VSWR maksimum 1,5 pada terminal 50 Ω unbalance, gain minimum 2,14 dBi, omnidireksional berpolaritas linier. Antena ini harus dibangun dengan saluran strip kembar jajar, berdasarkan transformator chebyshev, untuk digunakan di udara atau hampa; menggunakan balun jenis monopol konik supaya berpita lebar tetapi tanpa lilitan pada toroida.Dengan kaidah saluran strip kembar jajar diperoleh konstruksi (susunan bahan dan ukuran masing – masing) sebagai berikut: N = 3,69 ≡ 4 tingkat, εr1= 2,193 (Kertas HVS = 3,06 cm), εr 2= 1,911(Kertas HVS = 3,28 cm), εr3 = 1,6512(Kardus stabilizer = 3,536 cm), εr4 = 1,438 (Kardus Printer = 3,78 cm). Menggunakan strip tembaga jajar lebar = 0,59 cm (w) x panjang = 13,656 cm (l) x spasi = 3,5 cm (s). Balun monopol-konik, tinggi = 3 cm (s), berterminal unbalance.Melalui pengujian spesifikasi di pekarangan IT Telkom didapat hasil sebagai berikut: di dalam VSWR maksimum 1,5 ternyata frekuensi kerja 800 MHz – 2700 MHz pada terminal ZT = 50 Ω unbalance, gain = 5,043 dBi pada frekuensi 1650 MHz, berpolaritas ellips. Untuk menempatkan frekuensi kerja 0,3 GHz – 3,0 GHz dari 800 MHz – 2700 MHz, memperbesar sudut catuan monopol-konik, untuk meyakinkan bahwa berpolaritas linier disarankan diuji di ruang tanpa gema berantena uji berberkas pencil.Kata Kunci : unbalance, chebyshev, monopol-konik, dan prototipe.ABSTRACT: Monopol 0,3 GHz – 3,0 GHz Chebyshev - Omnidirectional Caturcula Antenna is designed on two purposes, they are: 1. To supply a wideband unidirectional antenna prototype so it can be used by some operators at once therefore economize the load of tower. 2. To prove the hypothetic of first advisor which told antenna is a device which used as a transformator between free space and transmission lines.The Specifications of antenna that must be fulfilled are the working frequency 0,3GHz-3,0GHz in VSWR max. 1,5 at 50Ω unbalance, gain min. 2,14 dBi, omnidirectional pattern and linear polarization. This antenna was constructed with two strip rows, by using chebyshev transformator which is used in air or vacuum. This device is also using monopol-konik as balun to deliver a wideband antenna without any coil.Based on twin rows strips theory, construction is obtained (with the materials and size), like this: N = 3,69 ≡ 4 tingkat, εr1= 2,193 (A4 paper = 3,06 cm), εr 2= 1,911(A4 paper = 3,28 cm), εr3 = 1,6512(Printer cardboard= 3,536 cm), εr4 = 1,438 (Stabilizer cardboard = 3,78 cm). This antenna is also using brass strip with its size 0,59 cm (w) x 13,656 cm (l) x 3,5 cm (s). Monopol-conic feed was built, 20mm in height, terminal 50 Ω unbalance.By measurement of these specification in IT TELKOM’s garden , the results are : in VSWR maximum 1,5 , the working frequency 800 MHz – 2700 MHz at terminal Zt 50Ω unbalance, the value of gain 5,043 dBi at 1650 MHz , ellipse polarization. The hypothesis has been proved, it can be seen that all the results are proper to the specification, only the lower frequency and the polarization out of plan. To widen the range frequency 800 MHz – 2700 MHz by make the monopol-conic feed angle larger. For the ellipse polarization, it can be a linear one if it is measured in anechoic chamber with pencil beam antenna.Keyword: unbalance, chebyshev, monopol-conic, dan prototype