диафрагмированные волноводные фильтры / b8a70ab7-6786-40d7-8286-6bc47012dee9

stage of the LNA, respectively. The fabricated LNA has gain of 12.5 dB, noise figure of 2.72 dB, and IIP3 of 5 dBm, with power dissipation of 8 mW from 1.5 V supply voltage.

ACKNOWLEDGMENTS

This work was supported by the IC Design Education Center (IDEC) and Inter-university Semiconductor Research Center (ISRC).

REFERENCES

1.K. Lee and B.-I. Seo, The impact of semiconductor technology scaling on CMOS RF and digital circuits for wireless application, IEEE Trans Electron Dev 52 (2005), 1415–1422.

2.J.N. Burghartz, M. Soyuer, and K.A. Jenkins, Microwave inductors and capacitors in standard multilevel interconnect silicon technology, IEEE Trans Microwave Theory Tech 44 (1996), 100 –104.

3.I. Song and H. Shin, Optimization of cascode configuration in CMOS low-noise amplifier, Microwave Opt Technol Lett 50 (2008), 646 – 649.

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IEEE Radio Freq Integr Circ Symp, Philadelphia, PA (2003), 259 – 262.

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10.C.P. Yue and S.S. Wong, On-chip spiral inductors with patterned ground shields for Si-based RF IC’s, IEEE J Solid State Circ 33 (1998), 743–752.

©2009 Wiley Periodicals, Inc.

Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24645

Key words: UWB antennas; coplanar waveguides; printed monopole

1. INTRODUCTION

Recently, a tremendous attention has been focused on ultra-wide- band (UWB) communication systems; the standard UWB bandwidth runs from 3.1 to 10.6 GHz, these systems are suitable candidate for exchanging high-rate information. The need of this enormous information trade, for economic and security purposes, is necessary in hostile environment such as mines and confined areas [1]. To achieve such high-performance communication systems, UWB antennas need to be integrated.

In spite of their light weight, low cost, ease of integration, and conformal structure, printed antennas suffer from the narrowness of their bandwidth. To broaden the bandwidth of printed antennas, much effort has been made such as surface meandering, aperture coupled patches, or near frequencies resonators [2].

An efficient technique to increase significantly the antenna bandwidth is to use modified shape monopole antennas [3, 4]. These structures are implemented with both coplanar waveguide (CPW) and microstrip technologies. In previous work [5], we have proposed a circular slot CPW-fed antenna providing a bandwidth of 140% and an average gain of 2 dBi. Another modified monopole shape in microstrip technology has been successfully explored [6].

In this article, we propose a new modified monopole fed with a CPW line. The considered monopole uses a shape based on a binomial curve. In addition, the ground plane is no longer considered as rectangular surface but also obeys to a binomial curve. This configuration offers a new type of well-matched tapered monopole and tapered ground plane that achieve a bandwidth covering the UWB standard from 3.1 to 10.6 GHz. This structure is smaller than previously proposed ones [5]. In the following sections, the design approach is first presented to describe the effect of the key parameters on the antenna behavior. Then, obtained results are presented and discussed.

UWB BINOMIAL CURVED MONOPOLE WITH BINOMIAL CURVED GROUND PLANE

Mohamed A. Habib,1 Mourad Nedil,2 Azzeddine Djaiz,1 and Tayeb A. Denidni1

1 INRS-EMT, University of Quebec, Montreal, QC, Canada H5A 1K6; Corresponding author: habib@emt.inrs.ca

2 LRTCS, University of Quebec in Abitibi-Temiscamingue, Val d’Or, QC, Canada J9P 1S2

Received 9 January 2009

ABSTRACT: The design of a new ultra-wideband (UWB) coplanar waveguide antenna is presented. The proposed antenna is a printedcircuit monopole using coplanar technology. The radiating element is a modified monopole with an optimal shape based on a binomial function. The ground plane is also designed with the same law. Different orders of this binomial function are considered. The antenna shape and dimensions are optimized to achieve an UWB bandwidth operation covering the frequency range from 3.1 to 10.6 GHz. A prototype of the designed antenna was fabricated and measured. Obtained results show that the proposed antenna provides omnidirectional elevation pattern across the operating band. Results provided by simulations and measurements are presented and discussed; they show a good agreement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2308 –2313, 2009;

2. ANTENNA DESIGN

A common approach to achieve wideband operation for antennas is to conceive a thick dipole or monopole [7]. The shape and thickness of the monopole are critical parameters for obtaining wide bandwidth. For this kind of elements, the structure has to be matched over a large range of frequency. In this section, our new structure is presented. This configuration is based on a curved monopole, where the monopole edge curve is ruled according to a binomial-law curve. First, the design is described, and then, a

parametric study is carried out on the effect of several parameters on the antenna behavior.

2.1. Antenna Layout

The layout of the proposed antenna is shown in Figure 1. The antenna is etched on Rogers 5880 substrate with a permittivity of 2.2 and a height of 1.575 mm. As the antenna is realized with coplanar technology, all the metal is removed from one side of the substrate.

On the metallic side, a CPW line is etched. The central line has 1.87 mm of width and is spaced with 0.2 mm from each lateral ground plane side, as showed in Figure 1.

The ground plane is not kept entirely rectangular; for a length Yg, it becomes curved. The curve follows a binomial law given in Eq. (1). The line is then connected to a monopole. This monopole has a length Y and depends on the same binomial law curve, where Xg is the monopole half-width. However, these two binomial laws are set with different orders, n for the monopole and m for the ground plane, respectively.

The length of the rectangular part of the ground plane is set equal to the monopole one. Optimal antenna dimensions are listed in Table 1.

2.2. Parametric Analysis

The purpose of this antenna design is to achieve a large bandwidth, covering the UWB (from 3.1 to 10.6 GHz). Typically, an initial value of Y corresponds to a quarter wavelength of the lowest frequency. The width Xg and the binomial laws orders m and n will

compared with those from simulation software tool [8], and radiation patterns at different frequencies of UWB band are presented.

3. RESULTS AND DISCUSSION

An antenna prototype based on the optimized parameters was fabricated and measured. The antenna return loss was measured with Agilent 8722ES network analyzer, and the radiation patterns were measured over the UWB with a hybrid near-field/far-field antenna measurement system [9], RF-Lab, INRS in Montreal, Canada.

Figure 4 shows the experimental and simulated antenna return loss. From these curves, it can be concluded that the antenna provides a bandwidth from 3 to 10 GHz with a return loss below10 dB. Two close resonances can be observed, the first one at 4 GHz and the second one around 8 GHz. Current distribution at these frequencies are depicted in Figure 5.

The radiation patterns at different frequencies, namely 4, 7, and 10 GHz, are plotted in Figures 6 – 8, respectively. The radiation patterns in the H-plane at different frequencies are omnidirectional; they are similar to classical monopole radiation pattern for the H-plane. However, for the E-plane, the radiation patterns vary in the frequency; at lower frequencies, the structure behaves like a dipole, because the curved ground plane and the monopole branch act jointly like dipole arms [Fig. 5(a)]. Around 8 GHz [Fig. 5(b)], the E-plane is identical to monopole, the lower curved side of the structure behaves as a ground plane, and the beams are tilted by 30° with a null at 90°. At higher frequencies, higher modes will interfere and patterns change drastically. With the help of simulation tool, the antenna efficiency has been recorded to be 95% over the entire antenna bandwidth.

4. CONCLUSION

In this article, an UWB antenna has been designed. This mono- pole-shape antenna uses a third-order binomial law curve for both the monopole branch and the modified ground plane. The antenna has a small size (40 30 mm2) with a dipole-like radiation pattern for azimuth plane. For elevation plane, the antenna behaves like a dipole at 4 GHz. The monopole and the ground planes act similarly to the branches of this new dipole-like structure. Besides that, at 7 GHz, the current distribution resonates with the monopole edge and hence the structure behaves like a classical monopole. The antenna bandwidth meets UWB requirements.

REFERENCES

1.C.P. Fortier and P.-M. Tardif, Geolocation for UWB networks in underground mines, In: IEEE wireless and microwave technology conference (WAMICON 06), 2007, pp. 1– 4.

2.K.L. Wong, Compact and broadband microstrip antennas, Wiley, Hoboken, NJ 2002.

3.R. Chair and A.A. Kishk, Ultra wide-band coplanar waveguide-fed rectangular slot antenna, IEEE Antennas Wireless Propag Lett 3 (2004), 227–229.

4.M. Abbosh and M.E. Bialkowsky, Design of ultrawideband planar monopole antennas of circular and elliptical shape, IEEE Trans Antennas Propag 56 (2008), 17–23.

5.T.A. Denidni and M.A. Habib, Broadband printed CPW-fed circular slot antenna, Electron Lett 42 (2006), 135–136.

6.M.A. Habib and T.A. Denidni, Design of a new wideband microstrip-fed circular slot antenna, Microwave Opt Technol Lett 48 (2006), 919 –923.

7.W.L. Stutzman and G.A. Thiele, Antenna theory and design, 2nd ed., Wiley, New York, NY 1998.

8.HFSS v. 11, Ansoft Corp., Pittsburgh, PA.

9.Allwave corp., Available at: http://www.allwavecorp.com, Torrance, California.

©2009 Wiley Periodicals, Inc.

COUPLED MICROSTRIP LINE BANDPASS FILTER WITH HARMONIC SUPPRESSION USING RIGHT-ANGLE TRIANGLE GROOVES

Ashraf S. Mohra

Department of Electrical Engineering, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia; Corresponding author: amohra@ksu.edu.sa

Received 11 January 2009

ABSTRACT: A single grooved coupled line bandpass filter with improved pass band response and first harmonic suppression is described. The suppression of the first spurious harmonic was done by using rightangle triangle grooves in the middle of each of the coupled-microstrip lines that construct the bandpass filter. As the number of grooves increase as the shift in the operating frequencies increase also, so it is suitable to use less numbers of grooves as possible. A three stage bandpass filter using coupled-microstrip lines was designed, simulated, and realized to illustrate this idea. The simulated results illustrate a good performance for right-angle triangle groove over the corresponding rectangular groove. The measured S-parameters measurement of the realized bandpass filter shows the suppression of the second resonance frequency and less shift in the center frequency. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2313–2318, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24644

Key words: coupled microstrip line; bandpass filter; harmonic suppression; grooves

1. INTRODUCTION

Coupled-microstrip lines have been widely used in design of bandpass filters due to several attractive features such as compact size, low profile, and tightened capacitive coupling. The bandpass filters based on microstrip-coupled line have been widely used in many microwave systems [1, 2]. The required design parameters of bandpass filter can be easily derived for Butterworth, Chebyshev, or any other prototypes in many literatures [1–3]. However, the microstrip bandpass filter with uniform coupled-microstrip line sections usually suffers from the spurious passband at the second resonant frequency of the microstrip-line resonator. Consequently, it makes the upper stopband performance worse. This problem happened due to the inequality of the even and odd mode velocities of propagation in the inhomogeneous dielectric medium. For a given parallel-coupled-microstrip line structure, the odd mode is propagating faster than the even mode, so the phase constant for the odd mode is less than the corresponding for the even mode;odd even). In addition, the electromagnetic energy for the odd mode concentrates around the center gap between the coupled lines, whereas for the even mode, the electromagnetic energy concentrates around the metallic edges. Various techniques have been proposed to equalize the even and odd mode velocities or their electrical lengths [4, 5]. Although these techniques lead to the minimization of the harmonics responses, but it need to reconstruct and redesign the filter with new physical design parameters.

In fact, the equal width coupled-microstrip filters suffer from the presence of spurious passband at harmonics of the desired frequency. So, if the conventional parallel-coupled-line filter is used at the next stage of frequency converter in the typical RF communication module, it is very difficult to reject the harmonic signal that frequency converter generates. Consequently, these phenomena result in the degradation of system performance. To lower the rejection level of these harmonics, the low pass filter or