Dae-Heon Lee

Tapered Slot Antenna With Band-Notched Function for Ultrawideband Radios

A novel tapered slot antenna (TSA) with a band-notched function for ultrawideband (UWB) radios is proposed in this letter. By inserting an Archimedean spiral-shaped slot into a microstrip open-circuit circular stub of microstrip-slotline transition, a UWB operation with a notched frequency band can be obtained. Measured data for the optimized case show the bandwidth for the VSWR <; 2 to be 8.8 GHz (from 2.4 to 11.2 GHz) with a notched band frequency from 4.6 to 6.2 GHz. By inserting the resonance slot on the nonradiating part of the antenna, the proposed antenna is capable of avoiding the spatial-dependent bandstop characteristics. Also, the designed antenna has a small size of 50 × 50 mm2, which is a size reduction of 40% with respect to previous similar antennas.

A Method of Substrate Shaping to Improve Gain of Active-Element Pattern for Small Arrays

This letter proposes a method of substrate subtraction to improve the gain of an active-element pattern for individual elements in a small array. The proposed method is applied to a three-element controlled reception pattern antenna array, whose radiating elements are printed on a high-dielectric ceramic substrate. Then, three identical fan-shaped areas, placed between the array elements, are subtracted from the substrate, and their shapes are adjusted to avoid unnecessary power losses caused by the fringing field effect, leakage fields, and surface currents. The effects of the subtracted areas are also investigated as parametric studies to demonstrate the effectiveness of the proposed substrate shaping method. The results show that the gain can be increased by 0.7 dB due to lower effective dielectric loss compared to the full substrate.

Design of arc-shaped patch antenna arrays for GPS applications

This paper proposes the design of an arc-shaped patch antenna for GPS arrays that is composed of an arc-shaped patch with two parasitic elements. The antenna is then arranged in a three-element circular array with an inter-element spacing of about a quarter wavelength, and the isolation characteristics are further improved by inserting a slot to the ground plate. Detailed design parameters are optimized by using the GA, and reflection coefficient, axial ratio, and radiation gain are measured in a semi anechoic chamber. The results demonstrate that the antenna is suitable to be used for GPS antenna arrays with good circular polarization properties.