Kablosuz haberleşme uygulamaları için boyutu küçültülmüş basılı log-periyodik çift kutuplu anten

Abstract

The design of printed logperiodic dipole antenna for wireless communication systems  Size reduction by using first order semicircles in dipoles  Wideband, high return loss performance and low gain variation In this study, a printed log periodic dipole antenna (LPDA) depicted at left of Figure A is introduced. The antenna contains the modifications of feed point patch, semi-circle curves and slot for bandwidth and size improvements. The proposed LPDA provides sufficient return loss and gain performances within wide frequency band as shown at top right and bottom right of Figure A, respectively.Figure A. The photograph of the proposed LPDA (at left), S11 results of the proposed LPDA (at top right) and gain values of the designed antenna in the study (at bottom right)Purpose: The aim of this study is to design a compact size and wideband LPDA, which operates at several wireless communication applications. The proposed antenna is desired to have good return loss performance and almost constant gain over the operating frequency band. The antenna has the purposes of smaller size and wider bandwidth as compared to the standart LPDA and other printed LPDAs studied in the literature, which work at similar frequency bands. Theory and Methods:At the initial part of design method, theoretical formulations for log periodic antenna are used to obtain a standard LPDA around L-band. Then, feed point patches are added to increase the upper edge of the operating frequency band, and size reduction is achieved by using single semi-circle dipoles, which can be considered as first order iteration according to the fractal theory. Finally, rectangular slot located at the end of the feed line is inserted to increase overall of the frequency band of the proposed antenna. Results:Modifications (insertion of feed point patches, dipoles containing semi-circle curves and slots on the feed line) realized on the standard LPDA significantly increases the performance parameters of the proposed LPDA, and reduces the overall size. Accordingly, proposed LPDA is measured to give return loss values better than 10 dB and stable gain values (low gain variation) of 4.75 dBi ± 0.75 dBi at frequency band of 0,86 GHz -2,5 GHz, which includes popular wireless communication applications such as RFID, GSM, GPS, 3G, Bluetooth and 2.4 GHz Wi-Fi systems. Besides, a size reduction of about 14% is achieved as compared to the standard LPDA, and antenna dimensions smaller than antennas with Koch fractal shapes and the structures given in the literature are found. Conclusion:A compact, printed LPDA is designed, manufactured and measured. This novel antenna is concluded to have better performances (wider bandwidth, smaller size, lower gain variation) as compared to the standard LPDA and similar LPDAs in the literature. The proposed antenna can be a good candidate for wideband wireless communication applications, which include RFID, GSM, GPS, 3G, Bluetooth and 2.4 GHz Wi-Fi systems.