The round-corner design of an all symmetric edge-coupled bandpass filter (BPF) is presented. The manufacturing tolerances and its effects of frequency shift on the design of the edge-coupled are investigated. Consequently, the round-ended design method is proposed in order to compensate the open-end effect in the half-wavelength resonator section with the round-ended corners rather than decrementing the lengths in a conventional way, and an experience formula and a corresponding procedure are devised for the design of such filters. The widths of all the half-wavelength resonators are set equal to avoid discontinuities in the interior of the filter. The filter is realized on a ceramic filled soft substrate with dielectric constant of 6.2. For obtaining the de-embedded measured results at the device plane an in-house customized through-reflect-line (TRL) calibration kit is produced. Three kinds of filters at different center frequencies are manufactured, and their measured results are in good agreement with the simulated ones after calibration.
2. Sun, L.-N. and P.-X. Yuan, "Research of detection technology in X-ray security inspection equipment," China Measurement Technology, Vol. 32, No. 3, 20-23, 2006.
3. Sinclair, G. N., R. N. Anderton, and R. Appleby, "Outdoor passive millimeter wave security screening," Security Technology 2001 IEEE 35th International Carnahan, 172-179, Oct. 2001.
4. Anyong, H. and M. Jungang, "Prototype development of an 8 mm-band two dimensional interferometer synthetic aperture radiometer," Proc. IEEE IWISA, 2009.
5. Wang, N.-N., J.-H. Qiu, and W.-B. Deng, "Development status of millimeter wave imaging systems for concealed detection," Infrared Technology, Vol. 31, No. 3, 129-135, China, Mar. 2009.
6. Xue, Y., J. G. Miao, G. L. Wan, A. Y. Hu, and F. Zhao, "Prototype development of an 8 mm band 2-dimensional aperture synthesis radiometer," 2008 International GeoScience and Remote Sensing Symposium, V-413-V-416, Boston, 2008.
7. Nanzer, J. A. and R. L. Rogers, "Human presence detection using millimetre-wave radiometry," IEEE Trans. on Microw. Theory & Tech., Vol. 55, No. 12, 2727-2733, Dec. 2007.
8. Zheng, C., X. X. Yao, A. Y. Hu, and J. G. Miao, "A passive millimeter-wave imager used fconcealed weapon detection," Progress In Electromagnetics Research B, Vol. 46, 279-297, 2013.
9. Cohn, S. B., "Parallel-coupled transmission line resonator filters," IEEE Trans. on Microwave Theory & Tech., Vol. 6, No. 2, 223-231, Apr. 1958.
10. Matthaei, G. L., L. Young, and E. M. T. Jones, "Microwave Filters, Impedance-matching Networks and Coupling Structures," Artech House, 1980.
11. Gupta, K. C., R. Garg, I. Bahl, and P. Bhartia, Microstrip Lines and Slotlines, 2nd Ed., Artech House Inc., 1996.
12. Swanson, D. G. and W. J. R. Hoefer, Microwave Circuit Modelling Using Electromagnetic Field Simulation, Artech House Inc., 2003.
13. Feng, L., Z. Wan, and Q. R. Zheng, "An improved genetic algorithm optimizing microstrip filter with equal width," 2003 6th International Symposium on Antennas, Propagation and EM Theory, Proceedings, 2003.
14. Wang, A.-G. and Q.-N. Lin, "The design for band-pass filter of parallel coupled microstrip lines with equal width," Journal of Circuits and Systems, 43-47, 2000.
15. Kirschning, M. and R. H. Jansen, "Accurate wide-range design equations for the frequency-dependent characteristic of parallel coupled microstrip lines," IEEE Transactions on Microwave Theory and Techniques, Vol. 32, No. 1, 83-90, Apr. 1984.
16. Mongia, R., I. Bahl, and P. Bhartia, "RF & Microwave Coupled-line Circuits," Artech House Inc., 1999.
17. Hong, J.-S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, John Wiley & Sons Inc., 2001.
18. Liu, D. X., B. Gaucher, and U. Pfeifler, Advanced Millimeter-wave Technology, 238-239, John Wiley and Sons, Ltd., Publication, 2009.
19., "Agilent in-fixture microstrip device measurement using TRL calibration,", Agilent Poduct Note PN 8720-2, 1991.