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Type: Posts; User: volker@muehlhaus

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  1. Closed: Re: Need help for ADS equation reprentation...

    In ADS help, search for function dbmtov()



    That is function pow()

    You can find a list of functions here:
    Help > Simulation > Equations and Expressions > Measurement Expressions
  2. Closed: Re: Where to use this low gain and low profile Microstrip Patch Antenna?

    Because directivity is low, or because radiation efficiency is poor (high losses)?
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    Closed: Re: Place TX/RX Antenna?

    Network analyzer S21 measured from TX antenna to RX antenna



    More distance between the antennas, possible anechoic absorbing material to reduce leakage, reduce near field reflections ... it...
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    Closed: Re: Place TX/RX Antenna?

    Go and measure the coupling, instead of guessing.
  5. Closed: Re: how can I calculate the returnloss theoritically depending on the simulation resu

    We have an expected range of values based on experience. For an accurate test, compare to measurement.
  6. Closed: Re: How to check recevied power in the HFSS port?

    This sounds like the wrong workflow. Because of reciprocity, you can test the transmit case, which is much easier.
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    Closed: Re: make a mismatching circuit

    You need to work more carefully!!!

    Now your TL2/MRSTRUB is an open circuit (hopefully) and you line can "see" the 540° long TL6 plus 900° (ninehundred degree) long line TL7, which transforms the...
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    Closed: Re: How to design RF mixer

    Welcome to the lazy student forum.
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    Closed: Re: make a mismatching circuit

    C12 is a short at these frequencies, and TL2 transforms to an open at CTEE1.

    If you want to have a DC feed at CTEE2, add a lamba/4 line (narrow, high impedance) and then the radial strub.
  10. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    Sure, but you misunderstood me. You need a matching circuit because the transistor side impedance is not 50 Ohm, and that is where your gap creates the extra inductance in the matching circuit PCB.
    ...
  11. Closed: Re: I need your comments diversity antenna distribution system for UHF broadband

    Makes no sense to me



    That adds a lot of signal path loss (3dB from coupler etc) in front of the LNA, which means the noise figure goes up. I think your design with the separate LNAs first is...
  12. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    You can add a few nH in simulation and test it. The photo was for the matching circuit input, which is not a 50 Ohm environment. If it is low impedance, inductance matters more than for a high...
  13. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    Getting the reference planes is of course very important, so careful port extension might be required, depending on your port calibration method.

    But what is also required is careful connection,...
  14. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    I also don't understand your concern. The large "non-RF-style" elements behind the radial stub are on the DC-side of things.
  15. Closed: Re: Dear all experts, I need your help for Agilent ADS 2015 libraries

    This seems to be a special library or design kit.
  16. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    I think we're discussing different aspects here. Phase shift doesn't always mean change of impedance.

    The impedance measured into the amp - as seen from the load side - moves around the Smith...
  17. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    I don't get your point here - you seem to have 50 Ohm lines with 50 Ohm source/load, so the extra length will not change impedances seen by the DUT.
  18. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    Short and direct connection from connector ground to microstrip (backside) ground. Your ground path with these connector (not designed for this side mounting) has too much length in the photo.


    A...
  19. Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

    Try to make a better (shorter) connection from SMA ground to the PCB ground. At the moment, you have a bit too much path length there. Parasitic ground path inductance is as bad as signal path...
  20. Closed: Re: Efficiency of four fed patch antenna

    My explanation: For simultaneous excitation, the transmission from 1 to 3 looks like port 3 reflection to the software. Then it is not "loss" for an efficiency calculation.

    Why do you have 4 feeds...
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    Closed: Re: ADS and S11 Equations for L & C

    A frequency where the line can still be considered short, so that the curve is flat. For my RFIC component extraction with tiny dimensions, that low frequency could be 1GHz, but in other cases it...
  22. Closed: Re: Inductor question. Why current goes up then down instead of decreasing with frequ

    I think it's MHz.

    Your real world inductor has parasitic capacitances, which result in a rapid change of input impedance towards self resonance frequency.
    Have a look here:...
  23. Closed: Re: Comparison of two antenna polar plots

    Whatever is relevant for the application.

    It seems that you start from an arbitrary result (call it solution) and now try to find a problem to fit your solution ... :roll:
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    Closed: Re: ADS and S11 Equations for L & C

    Many years of experience with extracting RLGC and circuit models from S-params :-D



    Sure, you always get some numbers as a result, but these don't have a physical meaning (as a capacitance) at...
  25. Closed: Re: thought experiment to understand radio propagation.

    Yes, think of a satellite, which covers a large area because it can "see" a large area.

    Also think of radio towers for old TV (before satellite TV): they mount VHF/UHF antennas on high towers...
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