Design of Compact-Size and High-Q Resonator with Composit of Folded Meander-Line and Spiral

Design of Compact-Size and High-Q Resonator with Composit of Folded Meander-Line and Spiral

1Ki-Cheol Yoon

1RFIC Research Center, Kwangwoon University, 20 Kwangun-Ro, Nowon-Gu,

Seoul, 139-701 Korea

2Bhanu Shrestha,

2Dept. of Electronics Engineering, Kwangwoon University,

3Kwang-Chul Son

3Graduate School of Information and Contents, Kwangwoon University, 20 Kwangun-Ro, Nowon-Gu, Seoul, 139-701

AbstractIn this paper, a new compact and high loaded quality factor (QL) resonator with composite of folded meander- line and spiral structure on low dielectric substrate is designed and simulated. The proposed resonator is connected directly to feeding line in order to get high QL and frequency responses. The resonator is designed to operate at 5.5 GHz and the simulation result shows the QL value of 170. The entire size of resonator is 2.60 x 1.61 mm2.

KeywordsCompact size;hig loaded quality factor; folded meander-line; spiral; resonator

1. INTRODUCTION

   Recently, the mobile communication has rapidly grown with the extension of the wireless local area network (LAN) and intelligent transport system (ITS) service. There have been increasing researches on high loaded quality factor (QL)

   This type of U-shaped resonator is the called hair-pin resonator. The conventional hair-pin resonator [3] consists of electrical lengths as shown in Table I. As depicted in the Table , Zs is the characteristic impedance of the single line, Zpe and Zpo are the even-and odd-mode impedances of the capacitance-load parallel coupled lines and s is the electrical length of microstrip-line, pe and po are the even-and odd- mode electrical lengths of parallel coupled line [4].

   a

   Zss

   po

   b Zpo

   Zpe

   pe

   Zo

   Zo

   with sharp-skirt, high selectivity characteristics, and small size for the resonator as an ITS mobile communication

   system.

   Also, a high-QL resonator is essential for position detection in vehicle mobile communication. Thus, the QL is the most important parameter in a position detector because it determines the overall performance of the detective device. The cavity and dielectric resonator (3D) are promising elements because of its high-QL characteristic. It is, however, due to its three-dimensional (3D) structure, only limited to the system on chip (SoC) and integrated circuit (IC) realization but also is not adequate for mass production [1].

   In order to reduce the size of resonator, high dielectric (r) substrate can be used, but the cost is high [2]. In this paper, the compact-size and high-QL resonator with composite of folded meander-line and spiral structure is presented.

2. ANALYSIS OF THE COMPACT-SIZE RESONATOR

   A hair-pin resonator consists of g/2 open-circuited line with folded structure and 50 coupled feeding line as shown in Fig. 1 [3].

   Fig. 1. Schematic of the hair-pin resonator

   TABLE I

   Dimensions of the hair-pin resonator

   length	value [mm]	Parameter
   		Dielectric constant	Frequency [GHz]
   a	4.10	2.52	10.0
   b	3.45

   TABLE II

   Experimental results of the loaded quality factor

   Ref [#]	QL	Parameter
   		r	Freq. [GHz]	Size [mm2]
   [3]	82	2.52	10.0	1.35X1.96
   [5]	59	2.54	9.20	3.38X3.24

   The resonance conditions of hair-pin resonators can be obtained by the ABCD matrix, which expresses a transmission line and a capacitor [4]. Table II shows the experimental results for the QL and size.

   In the table, the exhibition of resonators has low QL and the size is larger than proposed resonator at 10 GHz.

3. PROPOSED RESONATOR

   The proposed resonator is composed of outer folded meander line and inner spiral structure as shown in Fig. 2. From the Figure, the Z1 is characteristic impedance of resonator and the Z0 is characteristic impedance of feeding line.

4. EXPERIMENTAL RESULT

   The simulation has been carried out by EM simulator tool, IE3D and the simulation result for QL of the proposed resonator is 170 at the resonant frequency of 5.5 GHz as shown in Fig. 4. Since the QL is higher, we can have a good input reflection coefficient characteristics.

   The loaded quality factor can be calculated from the equivalent circuit shown in Fig. 2 using the equation (1) as follows [6]:

   0

   Loaded Quality Factor (Q )

   Loaded Quality Factor (Q )

   L

   L

   -10

   -20

   -30

   21

   21

   -40

   -50

   -60

   -70

   Simulated, S Simulated, S

   Fig. 2. Structure of the proposed resonator

   0 1 2 3

   4 5

   11

   11

   Fre ency Hz]

   6 7 8 9

   qu [G

   The Z0 is 50 and the Z1 is 120 . Also, the w and s are the width of microstrip line in the resonator and a gap

   Fig. 4. Simulation result of the proposed resonator

   R 2Z

   between microstrip lines respectively. In the same way, l1 and l2 are lengths of the resonator. Then, the wavelength of a resonator is g/2. In this characteristic, the proposed resonator

   QL o

   o C R 2Zo

   (1)

   is coupled to directly connection with feeding line. In this

   way, the spiral meander line is built by folding to make the size small. Figure 3 shows the equivalent circuit of the proposed resonator.

   It can also be computed from the measured reflection coefficient, S11 as depicted in Fig. 5.

   S11

   0 dB

   Magnitude, [dB]

   Magnitude, [dB]

   3 dB

   Fig. 3. Equivalent circuit of the proposed resonator

   From the Figure, the L is inductance corresponding to the length of the resonator and the C is capacitance corresponding to the gap size in resonator. R is conductance

   o f

   Frequency [GHz]

   Fig. 5. Definition of the loaded quality factor measurement

   The loaded quality factor corresponds to the 3 dB bandwidth of S11 given by the equation (2).

   in microstrip line. Also, the Vs and Rs are voltage source and source resistance in feeding line and the RL is the load

   Q o

   L

   . (2)

   resistance. In the equivalent circuit, the circuit is like a spiral resonator circuit.

   The entire size of the proposed resonator is 2.60 1.61 mm2.

5. CONCLUSION

In this paper, a new reduced size with high-QL resonator and with composite folded meander-line and spiral structure. In this case, the proposed resonator is connected directly to couple the feeding line. The proposed resonator has used a low dielectric substrate and the size is decreased due to folded structure. The resonator is designed to operate at 5.5 Hz and the simulation result shows the QL value of 170. The total size of the resonator is 2.6 X 1.61 mm2. The resonator can be possible to fabricate with integrated passive device (IPD) in semiconductor technique due to its entirely planar structure. Also, it can be applied to wireless local area network (LAN) system and intelligent transport system (ITS).

REFERENCES

1. R. Jones and V. Estrick, Low Phase Noise Dielectric Resonator Oscillator, Proc. IEEE Symp. Frequency Control, pp. 549-554, May 1990.

2. K. C. Yoon, J. H. Kim, and J. C. Lee, Compact Narrow Band-pass Filter with g/4 Short Stubs Using Impedance Mismatching of the Transmission Line, Microwave Opt. Technol. Lett., vol. 52, no. 9, pp. 2002-2005, Sept. 2010.

3. Y. T. Lee, J. S. Lim, C. S. Kim, D. Ahn and S. W. Nam, A compact- size microstrip spiral resonator and its applications to microwave oscillator, IEEE Microwave and Wireless Component Lett., vol. 12, no. 10, pp. 375-377, Oct. 2002.

4. M. Makimoto and S. Yamashita, Microwave resonators and filters for wireless communication theory, design and application, Springer, 2001.

5. S. W. Seo, H. Y. Jung, J. Jeong, and H. Park, Design of an X-band oscillator using novel miniaturized microstrip hairpin resonator, Proc. Asia-Pacific Microwave Conf., pp. 1-4, Dec. 2007.

6. K. C. Yoon, H. Lee, J. G. Park, K. M. Oh, and J. C. Lee, Design of an I-band low phase noise oscillator using a new hair-pin resonator, Proc. European Wireless Technology Conf., pp. 202-205, Oct. 2008.