диафрагмированные волноводные фильтры / 6cbf7c90-bdb5-4ee5-b878-ec4cd7ebf2fd

slot-line mode when m € 0.2 mm. Meanwhile, this negligible fraction corresponds to the maximum of mode conversion.

IV. CONCLUSION

In this letter, an asymmetric overlay transition between a CPW and a microstrip line was studied. The mode conversion has been characterized by a spectral-domain analysis and the matrix pencil posttreatment.

The mode conversion between the coplanar Ževen. mode and the spurious slot-line Žodd. mode was found to be insignificant, whatever the lateral displacement between the top and bottom metallization may be. Concerning the studied structure, it appears that tolerance requirements of this lateral shift can be determined neglecting the mode conversion phenomenon in the CPW.

REFERENCES

1.G. Strauss, P. Ehret, and W. Menzel, ‘‘On Wafer Measurement of Microstrip-Based MIMICs without Via Holes,’’ 1996 IEEE MTT-S Dig., pp. 1399…1402.

2.J. J. Burke and R. W. Jackson, ‘‘Surface-to-Surface Transition via

Electromagnetic Coupling of Microstrip and Coplanar Waveguide,’’ IEEE Trans. Microwa†e Theory Tech., Vol. 37, Mar. 1989,

pp.519…524.

3.G. Strauss and W. Menzel, ‘‘A Novel Concept for MM-Wave MMIC Interconnects and Packaging,’’ 1994 IEEE MTT-S Dig.,

pp.1141…1144.

4.W. Menzel, W. Schwab, and G. Strauss, ‘‘Investigation of Coupling Structures for Coplanar Bandpass Filters,’’ 1995 IEEE MTT-S Dig., pp. 1407…1410.

5.H. Jin and R. Vahldieck, ‘‘Full-Wave Analysis of Coplanar

Waveguide Discontinuities Using the Frequency Domain TLM Method,’’ IEEE Trans. Microwa†e Theory Tech., Vol. 41, Sept. 1993, pp. 1538…1542.

6.G. Strauss and W. Menzel, ‘‘Millimeter-Wave Monolithic Integrated Circuit Interconnects Using Electromagnetic Field Coupling,’’ IEEE Trans. Comp., Packag., Manufact. Technol. B, Vol. 19, May 1996, pp. 278…282.

7.A. B. Kouki, R. Mittra, and C. H. Chan, ‘‘Analysis of a Thin Slot

Discontinuity in the Reference Plane of a Microstrip Structure,’’

IEEE Trans. Microwa†e Theory Tech., Vol. 41, Aug. 1993, pp. 1356…1361.

8.Y. Hua and T. Sarkar, ‘‘Matrix Pencil Method for Estimating Parameters of Exponentially Damped‡Undamped Sinusoids in Noise,’’ IEEE Trans. Acoust., Speech, Signal Processing, Vol. 38, May 1990, pp. 814…824.

9.T. Becks and I. Wolff, ‘‘Analysis of 3-D Metallization Structure by a Full-Wave Spectral Domain Technique,’’ IEEE Trans. Mi- crowa†e Theory Tech., Vol. 40, 1992, pp. 2219…2227.

10.M. Kahrizi, T. Sarkar, and Z. A. Maricevic, ‘‘Analysis of a Wide Radiating Slot in the Ground Plane of a Microstrip Line,’’ IEEE Trans. Microwa†e Theory Tech., Vol. 41, Jan. 1993, pp. 29…36.

11.L. P. B. Katehi and N. G. Alexopoulos, ‘‘Frequency-Dependent

Characteristics of Microstrip Discontinuities in Millimeter-Wave Integrated Circuits,’’ IEEE Trans. Microwa†e Theory Tech., Vol. MTT-33, Oct. 1985, pp. 1029…1035.

12.N. I. Dib, L. P. B. Katehi, G. E. Ponchak, and R. N. Simons, ‘‘Theoretical and Experimental Characterization of Coplanar Waveguide Discontinuities for Filter Applications,’’ IEEE Trans. Microwa†e Theory Tech., Vol. 39, May 1991, pp. 873…881.

13.C. Delabie, Y. Delplanque, P. Pribetich, and P. Kennis, ‘‘Matched Loads Simulation Using Ghost Basis Functions for Moment

Method Analysis: Application to Microwave Planar Circuits,’’ Microwa†e Opt. Technol. Lett., Vol. 7, Sept. 1994, pp. 632…637.

14.P. Pannier, L. Kadri, J. F. Carpentier, F. Huret, and P. Kennis,

‘‘Full-Wave Spectral Domain Analysis of Coplanar Discontinuities Using Numerically Matched Loads,’’ Microwa†e Opt. Tech- nol. Lett., Vol. 10, Dec. 1995, pp. 350…353.

15.P. Pannier, L. Kadri, C. Seguinot, P. Kennis, and F. Huret, ‘‘Multimode Matched Loads Simulation for Moment Method Analysis: Application to the Characterization of Asymmetric Discontinuities in Coupled Microstrip Lines and CPW,’’ to be submitted.

ˆ 1997 John Wiley & Sons, Inc.

CCC 0895-2477‡97

MILLIMETER-WAVE BANDPASS FILTER IN BILATERAL FINLINE WITH WINDOW-CUT RESONATORS

S. K. Koul1 and B. Bhat1

1Centre for Applied Research in Electronics Indian Institute of Technology

Hauz Khas, New Delhi 110 016, India

Recei†ed 11 July 1997

ABSTRACT: An E-plane bandpass filter in bilateral finline featuring minimum insertion loss in the passband is proposed. The filter consists of a cascade of inducti†e strips and window-cut half-wa†e resonators formed by cutting out the dielectric substrate in the region of the resonator sections. It is demonstrated that such filters can be designed using the closed-form expressions a†ailable for the metal insert filters. A typical Ka-band filter realized with fi†e window-cut resonator elements offers typically 1 dB insertion loss o†er a passband of about 0.5 GHz and a stopband rejection of greater than 50 dB at ‰0.75 GHz away from the center frequency. ˆ 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 332…334, 1997

Key words: E-plane circuits; millimeter wa†es; bandpass filters; windowcut resonators

1. INTRODUCTION

Bandpass filters with low passband insertion loss and high stopband attenuation are commonly required in communication and radar systems; particularly in diplexers and triplexers. For operation at millimeter-wave frequencies up to about 100 GHz, such filters are generally realized in either E-plane metal insert configurations Š1…6‹ or large gap finlines Š4…7‹ by cascading half-wave rectangular slot resonators coupled through inductive strips. In these filters, since the conductor loss reduces with an increase in the slot width of the resonators, the highest Q-factor is achieved by keeping the slot width equal to the waveguide height. In the E-plane metal insert configuration, a pure metal insert is mounted in the E-plane of a rectangular waveguide. Because of the complete absence of dielectric substrate, these filters offer the advantage of low-loss performance similar to that of conventional waveguides. However, the dimensional tolerance of these filters is as stringent as in an air-filled waveguide filter. The large-gap finline filter with gap width equal to the height of the waveguide, known as the E-plane finline filter, alleviates this problem to some extent by concentrating most of the energy within the dielectric substrate. This filter, however, includes in it the loss due to the dielectric substrate.

This letter presents an improved version of the E-plane finline filter in which the dielectric substrate in the region of

the half-wave resonator sections is completely removed so as to form window-cut air resonators.

2. FILTER CONFIGURATION AND DESIGN

Figure 1 shows the proposed configuration of the bandpass filter in bilateral finline. Among the various finline configurations available, the bilateral finline is the most preferred for filter applications in view of its overall advantages in terms of low insertion loss, large mono-mode bandwidth, and less sensitivity to mechanical tolerances •8‚. The filter configuration shown in Figure 1 differs from the large-gap bilateral finline bandpass filters reported so far •4ƒ7‚ in that the dielectric substrate in the region of the resonators is cut out to form air-filled Žcalled window-cut. resonators.

Extensive literature exists on the accurate theoretical analyses of E-plane bandpass filters in finline and metal insert configurations which take into account the higher order mode interaction between the discontinuities, as well as the effects of finite thickness of the dielectric substrate and metal inserts •1, 4ƒ7, 9, 10‚. While these rigorous methods offer accurate design data, the programs for numerical computation are quite complex. Hong •3‚ has reported a simple, practical design procedure for the design of E-plane metal insert filters. In this design, each inductive septum is modeled as a symmetrical T-equivalent network, and the filter is represented in terms of its dominant mode-equivalent circuit as a cascade of inductive T-networks connected by uniform transmission line sections. Hong has provided simple models for the series and shunt inductive elements of the T-network for different normalized geometric parameters by using the

scattering matrix formulation of the septum and generating a large amount of numerical data.

Using the closed-form formulas of Hong •3‚, several three-resonator and five-resonator bandpass filters were designed at 35 GHz, and were implemented as window-cut bandpass filters in bilateral finline. While designing, the thickness of the metallized substrate was substituted for the metal insert thickness. After printing the circuit pattern on both sides of the substrate, the unmetallized resonator portions were cut to form air-filled half-wave resonators. The substrate carrying the filter pattern was then assembled in a split-block Ka-band waveguide housing. Experimentally, the measured center frequency of these filters was found to be slightly higher than the theoretical value. With a slight trimming of the resonator lengths, it was possible to match the center frequency. For example, in the case of the five-reso- nator filters, the center frequency could be matched by trimming Ženlarging. the central resonator by about 2ƒ3% and the two resonators adjacent to the central resonator by about 1ƒ1.5%.

3. PERFORMANCE

Figure 2, shows the disassembled view of a five-resonator bandpass filter designed at 35 GHz and its measured transmission loss characteristic. The dimensions of the various resonator and inductive strips of the insert after etching were within …0.02 mm with respect to the theoretically calculated values. Experimentally, the central resonator was trimmed by about 3% and the adjacent resonators by about 1.2% to match the center frequency. The calculated as well as the

Figure 2 Measured transmission loss characteristic of the filter of Figure 1. a • 7.112mm, b • 3.556 mm, d • 0.127 mm, ‚r • 2.22, t • 15 „m, h • 3.4775 mm, e • 1 mm. Dimensions of the inset Žin

1.96, d2 • 4.94, d3 • 5.29, l1 • 3.56, l2 • 3.59, l3 • 3.65: Ža. performance of transmission loss; Žb. photograph of hardware

final dimensions of the filter after trimming are listed in Figure 2. The filter offers an insertion loss within 1 dB over a passband of 0.5 Ghz, and a rejection of more than 50 dB at …0.75 GHz away from the center frequency.

4. CONCLUSION

An improved version of the E-plane bandpass filter in bilateral finline with window-cut air resonators is realized using the simple closed-form formulas reported by Hong †3‡ for metal insert filters. The shift in the center frequency can be easily adjusted by slight trimming of the lengths of the inner resonators by about 1ˆ3%. This filter combines the advantages of the metal insert filter in offering a high Q-factor and that of the bilateral finline filter in offering more relaxed dimensional tolerances. The filter is simple to design and fabricate, and offers the flexibility of final trimming.

ACKNOWLEDGMENTS

The authors wish to thank Mr. N. K. Gupta and Mr. S. Grover for their experimental support, and the Directorate of Training and Sponsored Research ŽDRDO. for their financial help.

REFERENCES

1.R. Vahldieck, J. Bornemann, F. Arndt, and D. Grauerholz, ‘‘Optimized Waveguide E-Plane Metal Insert Filters for Millimeter Wave Applications,’’ IEEE Trans. MicrowaŒe Theory Tech., Vol. MTT-31, Jan. 1983, pp. 65ˆ69.

2.V. Postoyalko and D. S. Budimir, ‘‘Design of Waveguide E-Plane

Filters with All-Metal Inserts by Equal Ripple Optimization,’’

IEEE Trans. MicrowaŒe Theory Tech., Vol. 42, Feb. 1994, pp. 217ˆ222.

3.J. S. Hong, ‘‘Design of E-Plane Band Pass Filters Made Easy,’’ Proc. Inst. Elect. Eng. Vol. 136, Pt.H, June 1989, pp. 215ˆ218.

4.R. Vahldieck and W. J. R. Hoefer, ‘‘Finline and Metal Insert

Filters with Improved Pass Band Separation and Increased Stop Band Attenuation,’’ IEEE Trans. MicrowaŒe Theory Tech., Vol. MTT-33, Dec. 1985, pp. 1333ˆ1339.

5.J. Bornemann, R. Vahldieck, and D. Grauerholz, ‘‘Optimized

Low-Insertion Loss Millimeter Wave Finline and Metal Insert Filters,’’ Radio Electron. Eng., Vol. 52, Nov.•Dec. 1982, pp. 513ˆ521.

6.F. Arndt, ‘‘Status of the Rigorous Design of Millimeter Wave Low Insertion Loss Finline and Metallic E-Plane Filters,’’ J. Inst. Electron. Telecommun. Eng., Vol. 34, 1988, pp. 107ˆ119.

7.F. Arndt, J. Bornemann, D. Grauerholz, and R. Vahldieck,

‘‘Theory and Design of Low Insertion Loss Fin-Line Filters,’’

IEEE Trans. MicrowaŒe Theory Tech., Vol. MTT-30, Feb. 1982, pp. 155ˆ163.

8.B. Bhat and S. K. Koul, Analysis, Design and Applications of Finlines, Artech House, Norwood, MA, 1987.

9.Y. C. Shih and T. Itoh, ‘‘E-Plane Filters with Finite-Thickness Septa,’’ IEEE Trans. MicrowaŒe Theory Tech., Vol. MTT-31, Dec. 1983, pp. 1009ˆ1013.

10.J. Dittloff and F. Arndt, ‘‘Rigorous Field Theory Design of Millimeter Wave E-Plane Integrated Circuit Multiplexers,’’ IEEE Trans. MicrowaŒe Theory Tech., Vol. 37, Feb. 1989, pp. 340ˆ350.

Ž1997 John Wiley & Sons, Inc.

CCC 0895-2477•97

NONLINEAR STRETCHING FOR ENHANCED LEARNING OF THE BACKPROPAGATION ALGORITHM IN TARGET RECOGNITION

Yi Ge,1 Soyoung S. Cha,1 Jiajun Zhang,2 Li Zhang,2 and Anzhi He2

1Department of Mechanical Engineering University of Illinois at Chicago Chicago, Illinois 60607

2Department of Applied Physics

Nanjing University of Science and Technology

Nanjing, P.R. China

ReceiŒed 17 June 1997

ABSTRACT: In spite of its relatiŒely slow learning speed, backpropaga- tion (BP) is one of the most popular neural network training algorithms. Here, a method based on nonlinear stretching is presented that modifies the actiŒation function in a BP algorithm to speed up the conŒergence in