Type: Posts; User: jesuschrist

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  1. Replies

    Closed: Eb/No to BER formula for QPSK

    I am trying to find the formula for the BER vs Eb/No curves but I only see the curves themselves as 10^-6 BER is about 10.5 Eb/No


    what is the formula to get these results?
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    Closed: Re: CST Field Contours bad resolution?

    It is a graphical thing. See the mesh lines ? they match with the hexahedral mesh lines. If you have the frequency domain solver you can use it with fine triangular mesh around the edges if it is...
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    Closed: Re: Question about LNA stability resistor

    Use a series 0 ohm or 5 ohm resistor at the output of transistor since transistor has a low resistance it will have low consumption.
  4. Closed: Re: [moved] I have a problem using waveguide port for my horn antenna in CST.

    another solution to your problem is to design a waveguide bend. If you bend all of their guides to upwards or downwards you can place waveguide ports because now they will always be on the same...
  5. Closed: Re: [moved] I have a problem using waveguide port for my horn antenna in CST.

    If they are the same antennas and if you think they wont interact with each other you can take field source of the horn and then use it for simulations.
  6. Replies

    [SOLVED]Closed: Re: Good wire for small antenna

    You can use RG402 coax which has 1.3mm core diameter.
  7. Closed: Re: 10GHz Corrugated Horn Antenna Design Problem

    You might have a measurement error as well if you are not using a professional setup. Happened to me once where the controller unit showed 60 degrees but actually it turned the motors 90 degrees. so...
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    Closed: Re: Tracking in satellite communications

    AUtotracking antennas employ feeds called multimode tracking feeds. There are few versions of it.Some use 4 horn antennas and use the sum and difference of signal levels, Some use TM01 mode for...
  9. Closed: Re: 10GHz Corrugated Horn Antenna Design Problem

    where is your port ? are you using slow wave structure(such as corrugated waveguide) for obtaining polarization or septum polarizer?What is your axial ratio? If you haven't done the whole system...
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    [SOLVED]Closed: Re: Polarizer axial ratio

    I solved it. I was comparing first mode and second mode for phase angle which ofcourse gives 90 degree difference all times.If you are holding the polarizer 45 degree angled.
  11. Replies

    [SOLVED]Closed: Polarizer axial ratio

    Hi. I'm trying to design a Ka band Tapered corrugated polarizer. I somewhat was able to keep phase difference stable but the S parameters differ alot. What i was trying to ask when I search the...
  12. Replies

    Closed: Re: C band SATCOM question

    It is not weaker it is about the wavelength of the C band. For parabolic reflectors the directivity equation is G=10*log_10(k*((pi*D)/lambda)^2)) where k= efficiency factor generally between 0.5-0.8,...
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    Closed: Re: CST Multiple Ports Issue

    You can use post processing for it. If you want to excite the system from multiple ports you can use combine results function aswell.
  14. Replies

    Closed: Re: Higher order modes waveguides

    Higher order waveguides are sometimes used in circular waveguides such as TE21 mode couplers for target acquisition in radars or satellite communication systems.As stated before they can couple to...
  15. Closed: Re: What are the Design parameters of Vivaldi antenna?

    You can type in "cst vivaldi antenna" to youtube.
  16. Closed: Re: Please How I get E-Field theta and E-Field phi in one diagram using CST

    you can use template based post processing. Assuming you want farfield properties, Just go to Farfield properties> Farfield Result and from there you can select a quick configuration in the list like...
  17. Closed: Re: Spectrum Analyzer weird results from LNA

    Yes sometimes when i stick my thumb or multimeter over the 3rd stage it goes away. But solved the problem by replacing the capacitors at rf out side with other values i had, now works fine. Thank...
  18. Closed: Re: Spectrum Analyzer weird results from LNA

    Last stage is actually a bfp780 a dirivng amplifier to increase P1db. Also I checked the oscillations again and it shows oscillations 864 mhz and it's multiples.First two stages is from macom maal...
  19. Closed: Spectrum Analyzer weird results from LNA

    Hi.I have designed an LNA for S-band between 2.2-2.4 GHz bands. The thing is when i test it i see this weird stuff on Spectrum analyzer like some 50 MHz signal is getting mixed in.I couldnt really...
  20. Closed: Re: Semi-rigid vs flexible cable for antenna feed

    it is for a cassegrain reflector antennas.power dividers,couplers and lna will be all around the feed for a compact design. They all will be in a metal cylinder cover and the cover can't exceed the...
  21. Closed: Semi-rigid vs flexible cable for antenna feed

    I designed an antenna feed that is capable of monopulse tracking.What I wanted to ask was which cable is better to use for both monopulse and antenna feed cable.I would like to use flexible cable...
  22. Replies

    Closed: Horn Antenna to coax pin feed

    Hi. I've designed a waveguide to coax adaptor for an S band feed horn. The thing is when I was designing the conductor that goes into the waveguide I didn't check available product length and took...
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    Closed: S11 smith chart contour too big

    Hi. I designed an S band LNA and fabricated it but there is a little problem. S11 and S22 of the circuit is nowhere near the simulation
    Here is the both measurement and simulation results. What...
  24. [SOLVED]Closed: Re: LDO tps7a4701 not working as intended.

    thank you looks like i misunderstood the datasheet. Well i adjusted the resistor after Vdc from 10 ohm to 56 ohm and now it works.
  25. [SOLVED]Closed: LDO tps7a4701 not working as intended.

    Hi. For my LNA design I was using tps7a4701 as a regulator to supply DC voltage to circuit. I designed the pcb according to datasheet and used any-out option and it should give 4V all times. Now i...
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