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Type: Posts; User: vfone

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  1. Replies
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    Closed: Re: Noise Source generator Circuit

    An Emitter-Base junction of a BJT transistor can generate noise up to 2GHz, when a high current Zener diode can generate white noise up to 6GHz.
    ...
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    Closed: Re: radar for object detection

    Automotive radars use very complex algorithms to process the signals coming from various targets. Usually the radar chip manufacturers (Infineon, NXP, TI) provide some very basic algorithms just to...
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    Closed: Re: Switching of Mobile Networks

    The name of this phenomenon is: intra-mode handover (and some time, vertical handover or intra-RAT handover):

    https://en.wikipedia.org/wiki/Handover...
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    Closed: Re: Dipole vs Patch Antenna for indoor wifi

    That one may not be a dipole antenna and may be a collinear antenna, which gives more dB's of gain than a simple patch antenna.
    Are very few chances that the radio waves from the omni-directional...
  5. Closed: Re: What can prevent two BT devices to connect successfully

    Bluetooth devices CAN NOT be paired to ANY other Bluetooth device.
    Bluetooth pairing compatibility depends on both, Hardware and Software:
    ...
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    Closed: Re: Turn long wire into antenna

    The length of the existing wire will not be changed.
    The only thing that you have to do is to INSERT inside of the existing wire, the 35cm length dipole.
    The dipole will be done from a piece of...
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    Closed: Re: Turn long wire into antenna

    You can do this dipole antenna. The total length of a half-wavelength dipole at 433MHz will be 35cm (Lamda=70cm and Lamda/2=35cm).
    You have to put two isloators at each end of the dipole.
    Also, if...
  8. [SOLVED]Closed: Re: Star topology chipset for long range (high power) comms

    ETSI regulations applies for entire Europe (and many other countries from all over the world as associates or observers), not only Western Europe.
    ...
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    Closed: Re: Pulsed microwave beam conundrum

    Remove the battery in your S7 cell phone. Put the SIM card in a different cell phone, preferable in an older model, not a smart phone.
    If still have these strong EM fields following you, (and...
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    Closed: Re: Pulsed microwave beam conundrum

    https://www.researchgate.net/figure/Frequency-spectrum-of-microwave-oven_fig1_268379441
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    Closed: Re: Pulsed microwave beam conundrum

    What about leakage from a neighbor microwave oven?
    I've seen microwave ovens from various manufacturers with totally different RF spectrum in 2.4GHz band.
  12. Closed: Re: How the output power changes by varying the capacitor connected in series with ga

    A capacitor placed in series with the gate of a MOSFET could change the input impedance matching of the transistor, so the gain will change, and the output power will change.
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    Closed: Re: Seeking wiring advice for Wifi router

    20 years ago Murata introduced first these type of connectors.
    They are cheaper and better performances than Hirose one (works up to 12GHz)....
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    Closed: Re: RF Switching with DC Pass

    You mentioned that the signals are between 0Hz (which is DC) and 2.4Ghz.

    My questions are: How a cable provider is transmitting a DC signal? How a DC signal is propagating through the air, between...
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    Closed: Re: Recommend a DC Power Supply

    https://www.tek.com/datasheet/series-2280s-precision-measurement-low-noise-programmable-dc-power-supplies

    https://www.tek.com/dc-power-supply/series-2260b-360w-720w-1080W-dc-power-supplies
  16. Closed: Re: What is the latest RF HEMT for prototype LNA?

    For this relative low frequency range you can use available SiGe transistors, which may have even lower noise figure than HEMT transistors at those frequencies.
    ...
  17. Closed: Re: HF transceiver separate active RX antenna connection

    I didn't arrive to the 500V rated voltage. The number was mentioned in the first post, as a guess if can be used in a 100W PA.



    My opinion that a 500V silver mica capacitor it will work in a...
  18. Closed: Re: Communication with geostationary satellites (~ 36 000 km distance)

    You can do a two-way radio communication with a moving satellite, without a rotary (motor) system antenna:
    https://www.youtube.com/watch?v=bT131WBHKxc
    But these are Low Orbit satellites (altitudes...
  19. Closed: Re: HF transceiver separate active RX antenna connection

    U = SQRT(Power*R) = SQRT(100W*50 ohms) = 70V
    Most of the HF 100W transceivers use a 100nF/100V at the antenna output.
    A 500V mica capacitor would work at 1kW, as a series output capacitor at 50...
  20. Closed: Re: Methods of decreasing the coupling between two closely placed antennas

    Increasing distance between antennas would be the best option to lower coupling.
    Can chose using chip ceramic antennas, which due to their small dimensions gives you more opportunities where to...
  21. Closed: Re: HAM radio topic: EM based design of a 432 MHz high pass with 144 MHz rejection

    Just now I see the post #5 :-)
    I used lines with length of 40mm, and that is the reason I got higher values for capacitors. This has minor importance from the moment the results are pretty similar.
  22. Closed: Re: HAM radio topic: EM based design of a 432 MHz high pass with 144 MHz rejection

    For who is interested, I played a bit with this tiny BPF and I found the values of the 3 capacitors, which is 82pF for each of them.
    The dimensions of the microstrip lines are easy to get, because...
  23. Closed: Re: HAM radio topic: EM based design of a 432 MHz high pass with 144 MHz rejection

    This is an impressive 50dB narrow-band rejection.

    To stay in the same area of smart printed filter designs, here is an interesting BPF for 2m band which gives 62dB rejection in 73cm band. ...
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    Closed: Re: Loose Coupling for a coaxial resonator

    Better performance means a good compromise between higher Q, greater rejection, less insertion loss.
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    Closed: Re: Loose Coupling for a coaxial resonator

    I've seen some improved designs (and shapes) for the coupling loops which claims better performances. The loops are connected to the ground on the other side of the connector, near the walls. Worth...
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