臺灣博碩士論文加值系統

本論文主要是設計寬頻及多頻介質共振器天線，可應用於寬頻無線通訊系統。
在此論文中，我們在介質共振器內插入一空隙，以增強電場強度，提高輻射效率，而使頻寬增加。或挖一溝槽，擾動原本的電磁場分佈，降低共振器之品質因子，而達到寬頻的效果。利用此概念設計一雙頻介質共振器天線，可符合WiMAX與WLAN之規格。
在此論文中，我們也設計一介質共振器天線，使共振器之TEy111、TEy112、與TEy113的共振頻率互相靠近，利用孔隙耦合的方式饋入，以結合三個共振頻帶而達到寬頻的效果，並在介質共振器內部挖一溝槽，以增加水平面上的天線增益，可使用在WLAN 802.11a 的應用。
我們亦在介質表面鍍上一層金屬，形成一共振器。該共振模態之電場與電流可產生全方向性的輻射場型。並利用共平面波導饋入，使表面金屬成為一單極天線，結合單極天線與共振器的頻帶，可以達到47%的頻寬，並具有全方向性的輻射場型。
在一介質共振器內挖一井狀空腔，或在介質共振器挖一矩形溝槽，能降低該共振器的品質因子，而有效的增加天線的阻抗頻寬，再結合孔隙天線模態的頻帶，可設計一寬頻介質共振器天線，符合WLAN 802.11a之規格。
將隧道狀的空腔橫向插入一矩形介質共振器內，可以改變TEy112模態的電場分佈，該電場在介質上方的分佈與TEy111模態的電場分佈相似，因此具有相似的輻射場型，設計空腔與介質共振器的大小，使兩模態的頻帶相連而達到20%的頻寬，並符合WLAN 802.11a之規格。

Various wideband and dual-band antenna designs using dielectric resonators (DR) have been proposed. A rectangular DR antenna generally operates in its TE111 mode with a
typical bandwidth of 5-8%, depending on its permittivity and dimensions. The TE111 mode has its characteristic electric field distribution within the rectangular DR.
Modification in shape will perturb the electric field distribution. By inserting a thin air gap normal to the electric field into the DR, the electric field will be enhanced by several times. Hence, the radiation becomes more efficient and the Q factor of the DR is reduced,
rendering a wide impedance bandwidth. Notches or tunnels can also be carved off the DR to increase its bandwidth. The effects of shape modifications on the resonant frequencies are analyzed by using the reaction between the original and the perturbed field distributions. A rectangular DR with shape modification is designed to have dual-band characteristic with bandwidth covering 3.375-3.93 GHz (15%) and 5.08-5.415 GHz (6%), respectively.

Each resonant mode in the DR is associated with a unique radiation pattern.
For example, a rectangular DR operating in its TE111 mode has a broadside radiation pattern on the H-plane, while that operating in the TE112 mode has a null radiation on the H-plane. The field distribution in a DR becomes the superposition of individual field distributions of different resonant modes when the DR operates at the frequency between the resonant frequencies of different modes.

The impedance bandwidth can be increased by merging the bands associated with the TE111, TE112, and TE113 modes. The resonant frequencies of these three modes can be close by proper designing the DR dimensions, making the radiation pattern more consistent over the impedance bandwidth. Moreover, an asymmetric moat is caved off to tilt the beam and hence increase its directivity on the H-plane. A rectangular DR with an asymmetric moat is designed to provide a wide impedance bandwidth of 4.89-6.86 GHz, over which broadside radiation pattern is obtained

The interface between air and high-permittivity material can be approximated as a perfect magnetic condition (PMC) wall. If a DR is partially coated by metal, a new resonant mode appears. Coplanar waveguide is used to excite the new resonant mode of the metal-coated DR. The metal coating also acts as a monopole. Merging the bands of the DR and the monopole by proper designing their dimensions, a wide impedance bandwidth can be obtained (4.2-6.8 GHz), over which a nearly omnidirectional radiation pattern is achieved.

1 Introduction 1
2 Dual-band Split Dielectric Resonator Antenna 4
2.1 Introduction . . . . . . . . . . . . . . . . . 4
2.2 Antenna Configuration . . . . . . . . . . . 5
2.3 Prediction of Resonant Frequency Shift . . 6
2.4 Rectangular Dielectric Resonator with Shape Modifications . . . . . . . . . . 7
2.4.1 Field Enhancement by a Gap . . . 9
2.4.2 Effect of an Air Tunnel . . . . . . . 11
2.4.3 Modification by Engraving Notches 13
2.5 Design with Combination . . . . . . . . . 15
2.6 Conclusions . . . . . . . . . . . . . . . . . 19
3 Bandwidth Broadening of Dielectric Resonator Antenna by Merging Adjacent
Bands and Embedding an Asymmetric Moat 20
3.1 Introduction . . . . . . . . . . . . . . . . . 20
iii
3.2 Resonant Modes of Rectangular DR . . . . 21
3.3 ModeMixing . . . . . . . . . . . . . . . . 27
3.4 Rectangular DR with Moat . . . . . . . . 29
3.5 Conclusions . . . . . . . . . . . . . . . . . 33
4 Broadband Dielectric Resonator Antenna with Metal Coating 34
4.1 Introduction . . . . . . . . . . . . . . . . . 34
4.2 Resonant Modes of Coated DR . . . . . . 37
4.3 Monopole Mode of Metal Coating . . . . . 39
4.4 Antenna Properties . . . . . . . . . . . . . 39
4.5 Conclusions . . . . . . . . . . . . . . . . . 44
5 Broadband Dielectric Resonator Antenna with an Offset Well 45
5.1 Introduction . . . . . . . . . . . . . . . . . 45
5.2 Dielectric Resonator with A Well . . . . . 46
5.3 Slot Antenna with Dielectric Superstrate . 49
5.4 Results and Discussions . . . . . . . . . . 49
5.5 Conclusions . . . . . . . . . . . . . . . . . 51
6 Size Reduction of Dielectric Resonator Antenna with a Notch 52
6.1 Introduction . . . . . . . . . . . . . . . . . 52
6.2 Resonant Mode of Dielectric Resonator . . 53
6.3 Antenna Design . . . . . . . . . . . . . . . 56
6.4 Conclusions . . . . . . . . . . . . . . . . . 60
7 Wideband Dielectric Resonator Antenna with a Tunnel 61
7.1 Introduction . . . . . . . . . . . . . . . . . 61
7.2 ResonantModes . . . . . . . . . . . . . . . 62
7.3 Results and Discussions . . . . . . . . . . 67
7.4 Conclusions . . . . . . . . . . . . . . . . . 69
8 Conclusions 70

[1] A. A. Kishk, B. Ahn, and D. Kajfez, “Broadband stacked dielectric resonator antenna,” Electron. Lett., vol. 25, no. 18, pp. 1232-1233, Aug. 1989.
[2] R. Chair, A. A. Kishk, K. F. Lee, and C. E. Smith, “Broadband aperture coupled flipped staired pyramid and conical dielectric resonator antennas,” IEEE APS Int. Symp., vol. 2, pp. 20-25, June 2004.
[3] Z. Fan and Y. M. M. Antar, “Slot-coupled DR antenna for dual-frequency operation,” IEEE Trans. Antenna Propagat., vol.45, pp. 306-308, Feb. 1997.
[4] A. A. Kishk, Y. Yin, and A. W. Glisson, “Conical dielectric resonator antennas forwide-band applications,” IEEE Trans. Antennas Propagat., vol. 50, no. 5, pp. 469-474,Apr. 2002.
[5] A. A. Kishk, “Wide-band truncated tetrahedron dielectric resonator antenna excited bya coaxial probe,” IEEE Trans. Antennas Propagat., vol. 51, no. 10, pp. 2913-2917, Oct.2003.
[6] T. W. Li and J. S. Sun, “Dual-frequency dielectric resonator antenna with inverse Tshapeparasitic strip,” IEEE/ACES Int. Conf., pp. 384-387, Apr. 2005.
[7] S. M. Shum and K. M. Luk, “Characteristics of dielectric ring resonator antenna withan air gap,” Electron. Lett., vol. 30, no. 4, pp. 277-278, Feb. 1994.
[8] Y.-D. Kim, M.-S. Kim, and H.-M. Lee, “Internal rectangular dielectric resonator antennawith broadband characteristic for IMT-2000 handset,” IEEE APS Int. Symp.,vol. 3, pp. 22-25, June 2002.
[9] A. Laisn´e, R. Gillard, and G. Piton, “Robust slot-fed dielectric resonator antenna usingan intermediated substrate,” Electron. Lett., vol. 37, no. 25, pp. 1497-1498, Dec. 2001.
[10] A. Buerkle, K. Sarabandi, and H. Mosallaei, “Compact slot and dielectric resonatorantenna with dual-resonance, broadband characteristics,” IEEE Trans. Antennas Propagat.,vol. 53, no. 3, pp. 1020-1027, Mar. 2005.
[11] K. P. Esselle and T. S. Bird, “A hybrid-resonator antenna: Experimental results,” IEEETrans. Antennas Propagat., vol. 53, no. 2, pp. 870-871, Feb. 2005.
[12] K. W. Leung, K. M. Chow, and K. M. Luk, “Low-profile high-permittivity dielectricresonator antenna excited by a disk-loaded coaxial aperture,” IEEE Antennas WirelessPropagat. Lett., vol. 2, pp. 212-214, 2003.
[13] S. A. Long, M. W. McAllister, and L. C. Shen, “The resonant cylindrical dielectriccavity antenna,” IEEE Trans. Antennas Propagat., vol. 31, no. 3, pp. 406-412, May 1983.
[14] T. A. Denidni, Q. Rao, and A. R. Sebak, “Multi-eccentric ring slot-fed dielectric resonatorantennas for multi-frequency operations,” IEEE APS Int. Symp., vol. 2, pp.1379-1382, June 2004.
[15] T. A. Denidni and Q. Rao, “Hybrid dielectric resonator antennas with radiating slot fordual-frequency operation,” IEEE Antennas Wireless Propagat. Lett., vol. 3, pp. 321-323,2004.
[16] L. T. Wei and S. J. Shiun, “Wideband dielectric resonator antenna with parasitic strip,”IEEE/ACES Int. Conf., pp. 376-379, Apr. 2005.
[17] B. Li and K. W. Leung, “Strip-fed rectangular dielectric resonator antennaswith/without a parasitic patch,” IEEE Trans. Antennas Propagat., vol. 53, no. 7, pp.2200-2207, July 2005.
[18] C. S. D. Young and S. A. Long, “Investigation of dual mode wideband rectangular andcylindrical dielectric resonator antennas,” IEEE APS Int. Symp., vol. 4, pp. 210-213,Jul. 2005.
[19] J. I. Moon and S. O. Park, “Dielectric resonator antenna for dual-band PCS/IMT-2000,”Electron. Lett., vol. 36, pp. 1002-1003, June 2000.
[20] Z. Fan and Y. M. M. Antar, “Experimental investigation of multi-element dielectricresonator antennas,” IEEE APS Int. Symp., vol. 3, pp. 2034-2037, July 1996.
[21] K. Pliakostathis and D. Mirshekar-Syahkal, “Stepped dielectric resonator antennas forwideband applications,” IEEE APS Int. Symp., vol. 2, pp. 1367-1370, June 2004.
[22] R. F. Harrington, Time-Harmonic Electromagnetic Fields, McGraw-Hill, Int. Ed., 1961.
[23] H. Y. Yee, “Natural resonant frequencies of microwave dielectric resonators,” IEEETrans. Microwave Theroy Tech., vol. 13, pp. 256-256, Mar. 1965.
[24] A. K. Okaya and L. F. Barash, “The dielectric microwave resonator,” Proc. IRE, vol.50, pp. 2081-2092, Oct. 1962.
[25] T. Itoh and C. Chang, “Resonant characteristics of dielectric resonators for millimeterwaveintegrated circuits,” IEEE MTT-S Int. Symp., vol. 78, pp. 121-122, Jun. 1978.
[26] R. K. Mongia, “Theoretical and experimental resonant frequencies of rectangular dielectricresonators,” IEE Proc. Microwaves, Antennas Propagat., vol. 139, no. 1, pp.98-104, Feb. 1992.
[27] R. K. Mongia and A. Ittipiboon, “Theoretical and experimental investigations on rectangulardielectric resonator antennas,” IEEE Trans. Antennas Propagat., vol. 45, no. 9,pp. 1348-1356, Sept. 1997.
[28] Y. M. M. Antar, D. Cheng, G. Seguin, B. Henry, and M. G. Keller, “Modified waveguidemodel (MWGM) for rectangular resonator antenna (DRA),” Microwave Opt. Tech.Lett., vol. 19, no. 2pp. 158-160, Oct. 1998.
[29] Q. Rao, T. A. Denidi, and A. R. Sebak, “Broadband compact stacked T-shaped DRAwith equilateral-triangular cross sections,” IEEE Microwave Wireless Compon. Lett.,vol. 16, no. 1, pp. 7-9, Jan. 2006.
[30] F. R. Hsiao, C. Wang, K. L. Wong, and T. W. Chiou, “Broadband very-highpermittivitydielectric resonator antenna for WLAN application,” IEEE APS Int.Symp., vol. 4, pp. 490-493, June 2002.
[31] K. W. Leung and H. K. Ng, “The slot-coupled hemispherical dielectric resonator antennawith a parasitic patch: Applications to the circularly polarized antenna and wide-bandantenna,” IEEE Trans. Antennas Propagat., vol. 53, no. 5, pp. 1762-1769, May 2005.
[32] S. M. Shum and K. M. Luk, “Stacked annular ring dielectric resonator antenna excitedby axi-symmetric coaxial probe,” IEEE Trans. Antennas Propag., vol. 43, no. 8, pp.889-890, Aug. 1995.
[33] Y.-X. Guo, Y.-F. Ruan, and X.-Q. Shi, “Wide-band stacked double annular-ring dielectricresonator antenna at the end-fire mode operation,” IEEE Trans. Antennas Propag.,vol. 53, no. 10, pp. 3394-3397, Oct. 2005.
[34] R. K. Mongia, A. Ittipiboon, P. Bhartia, and M. Cuhaci, “Electric-monopole antennausing a dielectric ring resonator,” Electron. Lett., vol. 29, no. 17, pp. 1530-1531, Aug.1993.
[35] M. Verplanken and J. V. Bladel, “The magnetic-dipole resonances of ring resonatorsof very high permittivity,” IEEE Trans. Microwave Theory Tech., vol. 27, pp. 328-333,Apr. 1979.
[36] A. Ittipiboon, A. Petosa, D. Roscoe, and M. Cuhaci, “An investigation of a novelbroadband dielectric resonator antenna,” APS Int. Symp., vol. 3, pp. 2038-2041, July.1996.
[37] R. Chair, A. A. Kishk, and K. F. Lee, “Experimental investigation for wideband perforateddielectric resonator antenna,” Electron. Lett., vol. 42, no. 3, pp. 137-138, Feb.2006.
[38] R. D. Richtmyer, “Dielectric resonators,”J. App. Phy., vol. 10, pp. 391-398, June 1939.
[39] Y. Y. Hung, “Natural resonant frequencies of microwave dielectric resonators,” IEEETrans. Microwave Theory Tech., vol. 13, pp. 256-256, Mar. 1965.
[40] R. K. Mongia, A. Ittibipoon, and M. Cuhaci, “Low profile dielectric resonator antennasusing a very high permittivity material,” Electron. Lett., vol. 30, no. 17, pp. 1362-1363,Aug. 1994.
[41] K. Lan, S. K. Chaudhuri, and S. S. Naeini, “Design and analysis of a combinationantenna with rectangular dielectric resonator and inverted L-plate,” IEEE Trans. AntennasPropagat., vol. 53, no. 1, pp. 495-501, Jan. 2005.
[42] R. Chair, A. A. Kishk, and K. F. Lee, “Wideband low profile eye shaped dielectricresonator antennas,” IEEE APS Int. Symp., vol. 3A, pp. 582-585, July 2005.
[43] A. A. Kishk, A. W. Glisson, and G. P. Junker, “Bandwidth enhancement for splitcylindrical dielectric resonator antennas,” Progress in Electromagnetic Research, vol.33, pp. 97-118, 2001.
[44] M. T. K. Tam and R. D. Murch, “Half volume dielectric resonator antenna designs,”Electron. Lett., vol. 33, no. 23, pp. 1914-1916, Nov. 1997.
[45] K. L. Wong, N. C. Chen, and H. T. Chen, “Analysis of a hemispherical dielectricresonator antenna with an airgap,” IEEE Microwave Guided Wave Lett., vol. 3, no. 9,pp. 355-357, Oct. 1993.
[46] Y. Gao, B. L. Ooi, W. B. Ewe, and A. P. Popov, “A compact wideband hybrid dielectricresonator antenna,” IEEE Microwave Wireless Comp. Lett., vol. 16, no. 4, pp. 227-229,Apr. 2006.
[47] S. M. Deng, C. L. Tsai, S. F. Chang, and S. S. Bor, “A CPW-fed suspended, lowprofile rectangular dielectric resonator antenna for wideband operation,” IEEE APSInt. Symp., vol. 4B, pp. 242-245, July 2005.