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    Question about the definition of Quality factor

    Hello everyone, In Yue's journal in 1998 "on-chip spiral inductors with patterned ground shields for Si-based RFIC's". The definition of the quality factor is: Q=2*pi* (energy stored)/ (energy loss in one oscillation cycle). My question is, what is the purpose to add a scalar 2*Pi here ...
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    antenna gain and directivity in HFSS!

    I had the same question before but still no anwer.
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    The meaning of the port impedance of a lumped port (HFSS)

    Hello everyone: How does HFSS adjust the field of a lumped port to satisfiy the port impedance we assign? Thanks. TWang
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    NF measurement of direct-convertsion mixer

    Thanks Mazz! BTW, you mentioned about the Gain Method. Is that the typical way pepole use to measure the NF of a direct-conversion reciever ? Regards, Tao
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    Question about the Wilkinson Divider

    Thanks ! flyhigh Do you mean it is still possible for a three ports network to be reciprocal, lossless, and all-ports matched at the same time ? TWang
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    NF measurement of direct-convertsion mixer

    Hi Mazz Thanks for your answer. BTW, I found a noise source product from noisecom, which has the ENR as low as 10KHz (10KHz ~ 1GHz). If I use this one to calibrate the NF of the instrument first at IF frequency, and than, use another one (Agilent 346C 10MHz~26.5GHz) to be the noise input of the...
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    NF measurement of direct-convertsion mixer

    y factor direct conversion Hi everyone: Does anyone know how to measure the NF of a direct-conversion mixer ? Because it's a frequency converting device, it's difficult to find a noise source to cover both RF(5GHz) and IF(10KHz) bands, maybe we need two noise sources. One is for calibration of...
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    Question about the Wilkinson Divider

    Hi tyassin: thanks for your reply, but what i still don't understand is that since the Sxx and the S32 are all zero , how come there will be reflected wave passing through the resistor and causing loss? the S matrix is (assume port1 is input, port2 and port3 are outuputs) 0 -j/√2...
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    Question about the Wilkinson Divider

    Hi everyone: When i'm studying the wilkinson divider part of the Microwave Engineering (by D.M. Pozar). There's one question that confuses me. In Chap7.3 (Wilkinson power divider), it says the Wilkinson divider can be lossless when outputs are matched, but in Chap7.1 (Basic properties of...
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    why positive S11 of patch antenna ?

    Thank you guys for giving me these suggestions. According to my recent experience in simulating this antenna. I found that the air box should be bigger enough, but of course it will cost lots of time. Maybe it's better to use 2D simulator instead of 3D.
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    Question about the "Reciprocity"

    Hi rautio: Thank you for giving me such a good explanation. Now I know what it means by the current on a PEC doesn't radiate. Bravo !
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    Question about the "Reciprocity"

    Hi everyone: There is somthing i don't understand in the book "Time-Harmonic Electromagnetic Fields" by R.F. Harrington. Can anyone answer my question? In the end of the chapter 3-8,the Reciprocity part, the author want to tell us that an electric current impressed along the surface of a PEC...
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    why positive S11 of patch antenna ?

    Yes I did. The conclusion i have right now is sometimes the s11 is normal but sometimes it is not. Here is another result. i sweep the freq in step from 45G to 65G. This time it's normal again. Another problem confusing me is i have antenna efficiency larger than one, did anyone have such...
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    why positive S11 of patch antenna ?

    Here is the sim format i used. The solution frequency is 65GHz. I seperate the freq sweep to two parts, one is from 45~55GHz, the other one is from 55~65GHz, but the results show that there is a discontinuity at the bounary of 55GHz as the attached plot. It's so weird. [/img]
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    why positive S11 of patch antenna ?

    Hello everyone, It's a problem that confuses me very much. As I tried to use HFSS to simuate a 60GHz patch antenna, I got positive s11 all the time. Where were I wrong? Could anyone kindly tell me the possible reasons of this strange results. Thank you. the patch is 1.4mm x 1.4mm with...

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