DESIGN AND ANALYSIS OF MODIFIED CIRCULAR FRACTAL ANTENNA FOR S, C AND X-BAND APPLICATIONS

In this paper, presenting the design and analysis of Modified Circular Fractal Antenna (MCFA) for S, C and X- band applications. Used the defined range of Sband is 2GHz-4GHz, C-band is 4GHz-8GHz and X-band is 8GHz-12GHz. S-band communication antennas have application in weather, tracking, and microwave oven. Cband antennas are useful in telecommunication, satellite communication and X-band is useful in radar applications. The proposed antenna has been implanted on FR4-epoxy substrate with the dielectric constant of 4.4 and height of 1.6 mm. Circular fractal antenna exhibits all required parameters that depends on the sizq and feed line position of the circular patch. The antenna has also been fabricated with optimized dimensions and then tested. The proposed antenna is fed by a microstrip line feed. The proposed antenna has been designed and simulated by HFSS vs 13.0 (High Frequency Structure Simulator). The various antenna parameters such as return loss, VSWR, gain and radiation pattern has been calculated. This proposed antenna operates at five different frequencies 2.87GHz, 6.39GHz, 6.89GHz, 8.00GHz and 8.51 GHz. The vector Network Analyzer (VNA) of proposed antenna is used for the measurement of return loss, VSWR. The simulated and measured results are compared and are found to be a good relative values with each other. Small in size, reduction in construction costs are the advantages of proposed antenna.

Challenges in the EM-based design of modern telecommunication satellite antennas

Purpose This paper aims to introduce design challenges of modern telecommunication satellite antennas. The antenna farms accommodated on a satellite are systems of high complexity. From the radio frequency (RF) point of view, the most important design issues, e.g. high power applications in space (vacuum) or typical antenna scenarios (single/multi beam antennas), and their solution are considered. Design/methodology/approach The paper presents the application of electro-magnetic (EM) field simulation in the design and optimisation process. The design of a telecommunications satellite antenna splits into several areas, for which different types of EM field solvers are used. Findings The use of EM field solvers enables an accurate and efficient design approach of modern geostationary telecommunications satellite antennas. Due to the use of EM field solvers, an excellent agreement between predictions and measurement results on feed as well as antenna system level is achieved. Originality/value This paper gives an overview of state-of-the-art telecommunications satellite antenna architectures and their efficient RF design due to the use of EM field solvers. Typical high power effects and other design issues are explained. RF engineers are encouraged to work on this exciting topic to further improve the design process and to develop new satellite antenna and feed products.

DESAIN AWAL SISTEM SATELIT TELEKOMUNIKASI PERTAHANAN INDONESIA (PRELIMINARY DESIGN OF INDONESIAN MILITARY TELECOMUNICATION SATELLITE)

As the biggest archipelago in the world, Indonesia really needs satellite system to support its defense and security. Based on that, this research aims to produce the preliminary design of telecommunication satellite system needed for defense and security campaign in Indonesia. Per best practice in aerospace engineering, the satellite preliminary design is preceded by a satellite concept design. In the concept design process, the users’ requirements, in this case, the Indonesian military, are studied, and comparative study is done for military telecommunication satellite solution that other countries used. The results are the satellite mission requirements, and design constraints to be used in the satellite preliminary design. The preliminary design shows that 2 kinds of satellites are needed to accommodate the mission requirements. i.e. L-band for mobile communications and C-band for fixed-high-datarate communication. Based on the available slots and the design constraints, the L-band satellite will be placed at 123 E. The satellite will weigh 2200 kg, has a power capacity of 1 kW, and can provide data communication with the speed of 512 kbps. The C-band satellite, that will be placed at 118 E, will weigh 2400 kg, has power capacity of 1.5 kW, and can provide data communication with the speed of 10 Mbps. Both satellites can operate for 10 years. Abstrak:Indonesia sebagai negara kepulauan terluas di dunia amat memerlukan sistem satelit untuk menunjang sistem pertahanan dan keamanannya. Atas motivasi tersebut penelitian ini bertujuan untuk membuat desain awal sistem satelit telekomunikasi yang diperlukan untuk pertahanan dan keamanan di Indonesia. Sesuai kaidah perancangan satelit, proses desain awal didahului dengan pembuatan desain konsep. Pada proses desain konsep dilakukan pendefinisikan kebutuhan penggguna, dalam hal ini pihak TNI dan Kementerian Pertahanan, dan studi banding atas solusi satelit telekomunikasi pertahanan di mancanegara. Hasil desain konsep adalah persyaratan misi dan batasan desain, yang harus diacu pada tahap desain awal satelit. Desain awal, diantaranya, menetapkan desain muatan sehingga dapat mengakomodasikan misi, serta ukuran dan berat dari bus satelit, agar bisa memenuhi kebutuhan muatan. Hasil menunjukkan bahwa pemenuhan desain konsep hanya bisa dilakukan dengan desain awal 2 tipe satelit telekomunikasi, yakni dengan frekuensi L-band untuk komunikasi bergerak, dan frekuensi C-band untuk komunikasi statis dengan kecepatan tinggi. Sesuai ketersediaan slot yang menjadi batasan desain, satelit L-band akan ditempatkan di 123 BT. Satelit tersebut mempunyai berat 2200 kg, konsumsi daya 1 kW, dan dapat melayani komunikasi data dengan kecepatan 512 kbps. Satelit C-band, yang akan berada di 118 BT, mempunyai berat 2400 kg, kapasitas daya 1.5 kW, dan dapat melayani komunikasi data dengan kecepatan 10 Mbps. Kedua satelit tersebut dapat beroperasi selama 10 tahun.