V. I. Kalinichev – Ph.D. (Eng.), Kotel’nikov Institute of Radio Engineering and Electronics of RAS. E-mail: email@example.com
M. V. Vesnik – Ph.D. (Phys.-Math.), Kotel’nikov Institute of Radio Engineering and Electronics of RAS. E-mail: firstname.lastname@example.org
A. S. Ryabokul – ZAO “AKMETRON”. E-mail: email@example.com
A. V. Krol – ZAO “AKMETRON”. E-mail: firstname.lastname@example.org
The article is devoted to testing of the radiation characteristics of printed-ink antennas on the basis of their near-field measurements. Emphasis is placed on the paper substrate-based antennas. Measurements were carried out in the 2-3 GHz frequency range. The me-thod of near-field scanning along a flat surface based on the EMSCAN RFxpert ™ technology was used.
The article consists of an introduction and four sections. The introduction provides an overview of methods for testing antennas based on their near-field measurements. The second section provides a brief description of the near-field scanner RFX2 ™ and its characteristics. The key element of the scanner is a flat array of magnetic loop antennas arranged in a rectangular grid. The principle of operation is based on measurements of the magnetic field distribution near the antenna under test. The measured amplitude and phase distributions are mathematically transformed into the far field characteristics, such as radiated power, radiation directivity, gain, linear and circular polarization, efficiency. The main advantage of the method lies in its operation speed. The third section describes the antenna samples printed on a paper sheet and a polyimide film, and presents the measured characteristics of one of the samples on the paper substrate. The measured frequency characteristic of the return loss demonstrates the resonant frequency that is in good agreement with the calculated one. The main attention on this section is given to measurements using the near-field scanner. The measurement method is described in detail. The section contains the measured amplitude-phase distributions of the near field for one of tested loop antennas on the paper substrate and the corresponding radiation characteristics in the far field obtained from the transformation of the near field distributions. The fourth section contains an analysis of the results. It is shown that for the tested antenna on the thin substrate with bidirectional radiation in the elevation the measured total radiation power should be corrected (increased) by a certain amount depending on the specific conditions of the test. The measurement error is supposed to be mainly due to underestimation of the radiation power in the solid-angle areas adjacent to the scanning plane. The values of directivity, radiation efficiency and total efficiency of the antenna have also to be adjusted accordingly. The fifth section contains concluding remarks. Using the near-field scanner enables an express testing of radiation characteristics for printed-ink antennas in the laboratory conditions. It is supposed that the efficiency of the paper substrate-based printed-ink antenna can be increased by using higher-quality advanced paper. One of the promising applications for such antennas can be tags for RFID systems.
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