There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Introduction Review of Some Background Materials General Formulation of the Cavity Model Characteristics of the Rectangular Patch Characteristics of the Circular Patch The Annular-Ring and the Equilaterial Triangular Patch Introduction to Full Wave Analysis of Microstrip Antennas Some Methods of Tuning the Resonant Frequencies of Patch Antennas Broadbanding Techniques Size Reduction Techniques Dual and Multi-Band Designs Dual Polarized Patch Antenna Designs Circular Polarization Microstrip Arrays

Microstrip Patch Antennas

A single-layer microstrip-fed patch antenna with capabilities of both bandwidth enhancement and harmonic suppression is proposed. For this purpose, a pair of $\lambda $ /4 microstrip-line resonators is introduced and coupled in proximity to a rectangular patch. The wideband property can be obtained by making effective use of the two resonances introduced by the radiating patch and nonradiating $\lambda $ /4 resonators. Different from other reported dual-resonance patch antennas, the proposed antenna does not require the electrically thick substrate, so it has attractive low-profile property. Thanks to the good features of $\lambda $ /4 resonators and capacitive feeding scheme, harmonic radiating modes of the patch antenna can be significantly suppressed as highly demanded in modern highly integrated communication systems. The working principle, equivalent circuit, and design procedure are extensively described. Finally, a prototype antenna operating at 4.9 GHz is designed and fabricated. The measured results show that its bandwidth is 2.7 times wider than that of the traditional insert-fed patch counterpart, and the harmful spurious radiation from other higher order radiating modes has been effectively suppressed.

A Compact Microstrip-Fed Patch Antenna With Enhanced Bandwidth and Harmonic Suppression

A simple bandwidth enhancement method for low profile E-shaped patch antennas is presented. By introducing a distributed LC circuit to the E-shaped patch antenna, a new resonant frequency close to that of the E-shaped patch is obtained, thus the bandwidth is widened. Moreover, the air thickness of the E-shaped patch antennas is reduced to only 0.0344λ0. A prototype antenna operated at AMPS band (824-894 MHz) was fabricated and measured. Measured results show that the designed low profile antenna has an impedance bandwidth over 9% for VSWR<; 2, with a satisfactory radiation performance within the bandwidth. The proposed method is also applicable to the design of other types of low profile slot-loaded patch antennas.

Bandwidth Enhancement Method for Low Profile E-Shaped Microstrip Patch Antennas

i»?A very popularly used technique to realize broadband and compact microstrip antenna (MSA) is by cutting a slot at an appropriate position inside the patch. More frequently, U-slot and its variation, a half U-slot, have been used to increase the bandwidth (BW). In most of the available literature on U-slot cut antennas, a detailed explanation for broadband response due to U-slot has not been reported. In this paper, an extensive study for the broadband behavior for U-slot, half U-slot and double U-slot cut rectangular MSAs (RMSAs) is presented. The U-slot configurations with different aspect ratios (i.e., length-to-width ratio) for patch and slot dimensions have been studied. In U-slot and half U-slot cut patches, it has been observed that slot does not introduce any additional mode, but it modifies the fundamental and higher order mode resonance frequencies of the patch to yield broadband response. The slot also modifies surface current distribution at higher order mode to yield broadside radiation pattern characteristics over the complete BW, without any variations in the directions of principle planes. Further, in double U-slot cut RMSA, the second U-slot optimizes the impedance and frequency at modified higher order TM21 mode and, along with modified TM01 and TM20 modes, yields increase in the BW. This paper will give an insight into the functioning of U-slot cut antennas.

Analysis of Broadband Variations of U-slot cut Rectangular Microstrip Antennas

A compact variation of a U-slot-loaded rectangular microstrip antenna—a half U-slot (L-shaped slot) loaded rectangular microstrip antenna—is proposed. The bandwidth of a shorted compact square microstrip antenna is increased by cutting a quarter-wavelength step U-slot. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 556–559, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21049

Compact Broadband U-Slot-Loaded Rectangular Microstrip Antennas

The approximate equations to calculate the resonant length of various compact rectangular microstrip antennas like, C-shaped, H-shaped, and rectangular ring microstrip antenna, are proposed. The error in the calculated resonance frequency is <5%. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 498–501, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22161

Formulation of resonant frequency for compact rectangular microstrip antennas

The broadband E-shaped microstrip antenna is realized by cutting pair of rectangular slots on one of the radiating edges of rectangular microstrip antenna. While designing an Eshaped antenna at given frequency, the slot length is taken to be nearly quarter wave in length. However this simpler approximation does not give closer results. In this paper, first a comparison of slot frequency calculated by using quarter wavelength approximation against simulated data for an optimized E-shaped antenna, is presented, which shows larger error. Further a detailed analysis to study the effects of slot on broadband response in E-shaped microstrip antenna is proposed. It is observed that slots do not introduce any additional mode but reduces the resonance frequency of higher order orthogonal TM02 mode of the patch and along with fundamental TM10 mode yields broadband response. The slot also modifies the surface current distribution at TM02 mode thereby yielding broadside radiation pattern over complete bandwidth without any variations in the directions of principle planes. Further an analysis of rectangular slot cut rectangular patch is also presented. The rectangular slot reduces orthogonal TM01 mode frequency of the patch and along with its TM10 mode, yields broadband response. The proposed analysis gives an insight into the functioning of widely used E-shaped antenna, and it will help in designing them in given frequency band.

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Analysis of Broadband E-shaped Microstrip Antennas

The broadband and dual-band rectangular microstrip antenna is realized by cutting pair of toothbrush-shaped or step slots along the non-radiating edges of the patch. The toothbrush-shaped slot is said to introduce TMd0 mode in between the TM10 and TM20 modes of the rectangular patch and realizes broadband response. In step slot cut configuration, the slot introduces a mode near the TM10 mode resonance frequency of the patch and realizes dual frequencies. In this paper, a detail analysis to study the effect of slots on the broadband and dual-band response in these rectangular microstrip antennas (RMSAs) is presented. It was observed that the slot does not introduce any mode but modifies the resonance frequency of higher order orthogonal mode and realizes broadband and dual-band response. The slot alters the direction of surface currents at higher order mode and gives similar radiation pattern characteristics over the broader bandwidth and at the dual frequencies. In broadband RMSA, a formulation of...

Amit A. Deshmukh

Papers

Analysis of Broadband Variations of U-slot cut Rectangular Microstrip Antennas

Compact Broadband U-Slot-Loaded Rectangular Microstrip Antennas

Formulation of resonant frequency for compact rectangular microstrip antennas

Analysis of Broadband E-shaped Microstrip Antennas

Analysis of Slot Cut Broadband and Dual-band Rectangular Microstrip Antennas