Joung-Myoun Kim

Antenna Measurement Method in Fresnel Region by

The far-field pattern and gain obtained using the far-field measurement method can be highly accurate when the distance between the source antenna and the antenna under test (AUT) satisfies the Rayleigh far-field criterion. In this letter, we propose an improved Fresnel region measurement method that can be applied in a shortened distance between two antennas. The many Fresnel fields required are captured by changing angle phi of the scanning plane. This scanning involves rotating the roll positioners of the source antenna and the AUT in the same direction and by the same amount, and rotating the azimuth positioner in the horizontal plane. The radiation pattern and gain from the simulation and experimental measurements agreed closely with the reference far-field pattern and gain. The proposed antenna measurement method in Fresnel region by phi-variation scanning can be easily applied to most popular far-field measurement systems without any additional cost.

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In this paper, the spiral planar monopole antenna mounted on a Cellular/WCDMA handset is designed. Frequency characteristics is optimized with various design parameters. The two spiral lines are adopted in order to implement Cellular frequency bandwidth and WCDMA frequency bandwidth. The bandwidth of the realized antenna is GHz(10 %) and GHz(21 %) for VSWR which contain the proposed frequency bandwidth. In human head, the simulated value on 1 g and 10 g averaged SAR caused by electromagnetic wave radiated in the designed antenna is compared with the measured value. As a result, the measured values of 1 g and 10 g averaged SAR were similar to the simulated values, which were lower than the SAR guidelines.

-Variation Scanning

In this paper, we designed and fabricated the broadband probe with double ridged waveguide for broadband near-field measurements. An exponential taper ridge in the rectangular waveguide and novel waveguide transition were implemented for wideband impedance matching and compression of the higher modes. It has wideband characteristics and its measured impedance bandwidth ratio is approximately 123%(4.17:1) from 12.0 GHz to 50 GHz for SWR<3.0. And the peak radiation gain is 5.7~14.3 dBi. The performance of this probe is verified by the measured results and is in good agreement with the simulated results. It is possible that our designed broadband probe is applied to broadband near-field measurement under 50 GHz.

The Design and SAR Analysis of the Spiral Planar Monopole Antenna for Dual-Band

A compact and broadband dipole antenna for dual ISM-band applications is proposed and implemented on a laptop. The performances of the implemented antennas are validated by the comparison results with both measurements and simulations. As a result, we can obtain some useful results that may provide a better theoretical and experimental understanding of the relationship between the radiation characteristics and the antennas environment including its mobile application.