5. CONCLUSION In this paper, the subharmonic cascode FET mixer has been designed by using a single-gate cascode structure and driven by the second-harmonic component of the LO signal. As RF power was -30 dBm and LO power was 0 dBm, the designed mixer yielded a -47.17 dBm LO-to-RF leakage-power level, 10-dB conversion gain, -2.5 dBm OIP3, -12.5 dBm IIP3, and a -1 dBm 1-dB gain-compression point. Because the LO-to-RF leakage-power level of the designed subharmonic mixer is as good as that of a double-balanced mixer, the subharmonic cascode FET mixer can be used instead. However, the linearity characteristic of the de- signed mixer needs to be further improved for the mixer to be utilized in a real system. ACKNOWLEDGMENT This research was supported by the Hanyang University IT Re- search Center Project. REFERENCES 1. K.L. Fong and R.G. Meyer, Monolithic RF active mixer design, IEEE Trans Circ Sys II 46 (1999), 231–239. 2. S.A. Maas, Microwave mixer, Artech House, Norwood, MA, 1993. 3. C. Tsirons, R. Meierer, and R. Stahlmann, Cascode MESFET mixers, IEEE Trans Microwave Theory Tech MTT-32 (1984), 248 –255. 4. S. Liwei, C.J. Jonathan, and E.L. Lawrence, A wide-bandwidth Si/SiGe HBT direct conversion sub-harmonic mixer/down-converter, IEEE J Solid-State Circ 35 (2000), 1329 –1337. 5. A.C.A. Dias, D. Consonni, and M.A. Luqueze, High isolation sub- harmonic mixer, Microwave Optoelectron Conf IMOC99, 1999, pp. 378 –381. 6. Advanced Design System, Agilent Technologies, 2001. 7. RF/IF Designer’s Guide, Mini-Circuits, 2001. 8. http://www.semiconductor.agilent.com. © 2003 Wiley Periodicals, Inc. ON THE CONVERGENCE PROPERTIES OF THE METHOD OF AUXILIARY SOURCES IN 2D PROBLEMS WITH OPEN BOUNDARIES P. J. Papakanellos, I. I. Heretakis, and C. N. Capsalis Dept. of Electrical and Computer Engineering National Technical University of Athens 9th Iroon Polytechneiou St., 15773, Zografou, Athens, Greece Received 14 May 2003 ABSTRACT: In this paper, the convergence properties of the method of auxiliary sources (MAS) when applied to two-dimensional (2D) prob- lems with open boundaries are studied. Although such problems have been examined in the past, the relation of the solution errors with the sources’ locations has not been reported in detail. Herein, the conver- gence behavior in the case of a single infinite wire above a flat ground is thoroughly examined. The dependence of the boundary-condition er- rors on the number and spacing of the auxiliary sources is illustrated and general rules that govern their behavior are extracted. Finally, a few concluding remarks are outlined and their utilization for the ad- vancement of the MAS is briefly discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 518 –522, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop. 11221 Key words: numerical methods; method of auxiliary sources; ground effects INTRODUCTION The method of auxiliary sources (MAS) and the relevant numerical methods have been recently recognized to be special cases of the generalized multipole technique (GMT) [1– 4]. The MAS has been applied extensively to electromagnetic (EM) interaction problems involving closed dielectric or metallic structures [3, 4], but only a very small number of efforts for the application of the MAS to problems with open boundaries have appeared in the open litera- ture (see for example [3– 6]). However, the method theoretically applies to a wide range of problems involving open boundaries, such as radiation problems of antennas above the earth or sea, as well as scattering problems from closed structures near unbounded regions. From this point of view, the study of such problems is of great importance for yielding rules regarding the choice of the parameters related to the application of the method. For the ex- traction of general conclusions related to the dependence of the boundary-condition errors’ behavior on these parameters, it is Figure 7 Measured IMD characteristics TABLE 2 Measurement Result of the Designed Sub- Harmonic Cascode FET Mixer Parameters This Paper General Characteristics of Commercially Available Mixers Passive [7] Active [8] RF frequency (MHz) 1950 (1920–1980) NA LO frequency (MHz) 880 (865–895) NA IF frequency (MHz) 190 (RF–2LO) NA RF power (dBm) -30 NA LO power (dBm) 0 7–19 -5 IF power (dBm) -20 (RF–2LO = 190 MHz) -48 (RF–LO = 1070 MHz) NA Conversion gain (dB) 10 -7–6 9 OIP3 (dBm) -0.5 21–38 3 IIP3 (dBm) -10.5 NA P -1dB (dBm) -1 10–24 -8 RF-to-IF Leakage (dBm) -54.34 NA LO-to-IF Leakage (dBm) -28 (LO = 880 MHz) -50.5 (2LO = 1760 MHz) -19–12 -39 LO-to-RF Leakage (dBm) -19.5 (LO = 880 MHz) -47.17 (2LO = 1760 MHz) -29–21 -23 NA: not available. 518 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 39, No. 6, December 20 2003