A small printed antenna is described with a reduced ground-plane effect for ultrawideband (UWB) applications. The radiator and ground plane of the antenna are etched onto a piece of printed circuit board (PCB) with an overall size of 25mmtimes25 mmtimes1.5 mm. A notch is cut from the radiator while a strip is asymmetrically attached to the radiator. The simulation and measurement show that the miniaturized antenna achieves a broad operating bandwidth of 2.9-11.6 GHz for a 10-dB return loss. In particular, the ground-plane effect on impedance performance is greatly reduced by cutting the notch from the radiator because the electric currents on the ground plane are significantly suppressed at the lower edge operating frequencies. The antenna features three-dimensional omni-directional radiation with high radiation efficiency of 79%-95% across the UWB bandwidth. In addition, a parametric study of the geometric and electric parameters of the proposed antenna will be able to provide antenna engineers with more design information

Small Printed Ultrawideband Antenna With Reduced Ground Plane Effect

Apparatus, systems and techniques for using composite left and right handed (CRLH) metamaterial (MTM) structure antenna elements and arrays to provide radiation pattern shaping and beam switching.

Metamaterial antenna arrays with radiation pattern shaping and beam switching

A novel printed monopole antenna with dual widebands is presented for simultaneously satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The antenna structure consists of a rectangular monopole with a microstrip feedline for excitation and a trapezoid conductor-backed plane for band broadening. The measured 10 dB bandwidth for return loss is from 2.01 to 4.27 GHz and 5.06 to 6.79 GHz, covering all the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands

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Dual Wideband Printed Monopole Antenna for WLAN/WiMAX Applications

A novel band-rejected ultrawideband antenna with one parasitic strip is presented in this paper. It is designed to work on a substrate FR4 that has a thickness of 1 mm and relative permittivity of 4.6, and to operate from 3 to 17 GHz. The proposed antenna is fed by microstrip line and utilizes the parasitic strip to reject the frequency band (5.15-5.825 GHz) limited by IEEE 802.11a and HIPERLAN/2. The size of the antenna is 20/spl times/20 mm/sup 2/ and this antenna has good radiation characteristics. Effects of varying the location and length of the parasitic strip and the structure of the ground and monopole patch on the antenna performance have also been studied.

Analysis of the small band-rejected antenna with the parasitic strip for UWB

To prevent interference between ultrawideband (UWB) systems and existing wireless systems, creating notches in the UWB radiated field spectrum has been proposed. This filtering effect can be achieved by integrating a slot resonator to a UWB antenna. However, in printed monopole or dipole type UWB antennas, the notch frequency of the embedded slot depends on substrate and slot parameters. In this paper, we present a method to calculate, very accurately and efficiently, the notch frequency of such antennas. This method is validated by comparing theoretical and experimental results for 19 different slot width, slot length and dielectric constant combinations. The average difference is about 2%. We also assess the filtering action of slots from two aspects: the mismatch loss at the input and the radiation level in the far field. The sensitivity of the notch frequency to antenna parameters is also investigated.

Prediction of the Notch Frequency of Slot Loaded Printed UWB Antennas

In this paper, we propose a new ultra-wideband (UWB) antenna for UWB applications. The proposed antenna is designed to operate from 3.2 to 12 GHz. It consists of a rectangular patch with two steps, a single slot on the patch, and a partial ground plane. Details of the proposed antenna design and measured results are presented and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 399–401, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11392

A new ultra-wideband antenna for uwb applications

Another ID-HIP is also designed to verify the conclusion. The finger and space widths are 0.1 mm each, the finger length is 1.5 mm, and the finger number is 13. The substrate on which the structure is printed is 1.5-mm thick with relative permittivity of 2.65. The array spacing is 4.2 mm and the resonant frequency will be 5.82 GHz. A 20 20 array is fabricated, and a photo of the whole structure is shown in the bottom half of Figure 3. According to the measured result, the bandgap is from 5.7 to 6.8 GHz. For a conventional HIP with periodic spacing of 4.2 mm (with w 4 mm and g 0.2 mm), the resonant frequency will be 9.35 GHz. Thus, the ID-HIP is 30% smaller than conventional HIP. 4. CONCLUSION A novel high-impedance structure with interdigital elements has been presented. The interdigital elements are regarded as an interdigital capacitor in order to enhance the coupling effect of the adjacent elements. The design formula for an effective-circuit model has been given and two examples have been manufactured. The measured results show that the size of the high-impedance surface has been dramatically compressed, as compared to that of the conventional structure. This novel type of high-impedance surface will be valuable in practical applications such as circuits and antennas.

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Design of Dual-Band Antenna for the ISM Band Using a Backed Microstrip Line

Although the magnitude of the disturbance caused by the driving of the motor operated to secure the high-speed and precise directivity of the antenna is small, it acts as a major cause of impairing the image quality of the observation satellite, which requires precision directing performance. In order to acquire high-resolution image information through the improvement of the high-resolution observation satellite, proper vibration isolation and reduction design are required so that jitter generated when the directional antenna motor is driven is not transmitted to the main mission equipment. In this paper, the development process of the directional antenna vibration reduction device applied to real satellites and the effect of micro vibration reduction before and after application will be examined. This device was designed as a way to significantly improve the jitter problem by replacing only one gear in the directional antenna driving unit with a spring damper gear without any additional interface equipment. It was first applied and launched to a high-resolution earth observation satellite, and has been successfully operated so far.

Seok H. Choi

Papers

A new ultra-wideband antenna for uwb applications

Design of Dual-Band Antenna for the ISM Band Using a Backed Microstrip Line

Vibration Reduction Device for Directional Moving Satellite Antenna