Realization of a Second Harmonic Antenna for Rural Communications

Adit Kurniawan¹, Ahmad Hasyim¹ & Yuyu Wahyu²

¹School of Electrical Engineering and Informatics, Institut Teknologi Bandung

Jl. Ganesa 10 Bandung 40132, Telp. +62-22-2501661, Fax. +62-22-2534133

²Research Centre of Electronics and Telecommunications,

Indonesian Institute of Science

In this research, an active antenna operated at the second harmonic frequency is investigated, and is implemented using microstrip antenna material. The antenna consists of a FET oscillator which plays as a fundamental frequency oscillator and a frequency multiplier, and a patch antenna resonated at the second harmonic frequency as the radiator. A maximum second-harmonic output power can be extracted when the load impedance of the oscillator is optimized both at the fundamental and at the second harmonic frequencies. A rectangular patch antenna is used to radiate the second harmonic output power from the oscillator. The patch impedance is matched resistively at the second harmonic frequency. The patch antenna is fabricated using Diclad 522 microstrip substrates (relative permitivity e_r = 2.5) with a dielectric thickness of 1.57 mm. A GaAs FET AT-8250 transistor is used as an oscillator and a frequency multiplier and acts as the active component. Fundamental frequency is designed at 2,4 GHz band, so that the second harmonic frequency operates at 4,8 GHz band. The frequency is chosen to facilitate and to extend the needs of communications in rural areas using the unlicensed Industrial Scientific, and Medical (ISM) band. Operating the communication infrastructures intended for the use at 2.4 GHz band at its second harmonic frequency, is intended to alleviate interference levels at 2.4 GHz.

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