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Type: Posts; User: vfone

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  1. Replies
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    Closed: Re: Microstrip line and ground on same layer

    There is no reason to design a high-impedance microstrip line with nearby ground on the same layer, because any nearby ground will decrease the impedance of the line, and you will not have anymore a...
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    Closed: Re: Microstrip line and ground on same layer

    The rule of thumb that you ask for is that the ground plane on the same layer should be at a distance greater than 1.5 x width_of_the_line.
    For example if the width of the microstrip line is 1mm the...
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    Closed: Re: Question about PC3.5mm and SMA connectors

    3.5mm and SMA may be mechanically compatible, but for very precise measurements, connecting them results a small but measurable discontinuity.
    A damaged or out of spec SMA connector can damage a...
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    Closed: Re: Captured field by Array Antenna

    Seems that you know ALL the answers...before placing the questions here...
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    Closed: Re: Captured field by Array Antenna

    The total field of an antenna array is determined by the vector summation of the induction fields radiated by the individual antenna elements.
    This assumes that the current in each element is the...
  6. Closed: Re: How does intermodulation affect receiver system?

    Yes, you can say in this way...
  7. Closed: Re: How does intermodulation affect receiver system?

    Indeed...

    The main concern of intermodulation is reducing the receiver sensitivity.

    To understand how intermodulation level is measured:
    - the receiver is tuned on one of the frequencies of...
  8. Closed: Re: Can you help me get S-parameter file of Mitsubishi MGF4937AM and Infineon CFY67

    Unfortunately, today most of the universities do not bother teaching students how to measure s-parameters of a transistor.
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    Closed: Re: Relay selection for Ultrasonic signals

    And also, because ARJ2024 is a microwave relay the isolation is given only in dB.
    30dB isolation doesn't tell you anything about high-voltage isolation capabilities.
    As was mentioned, any of the...
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    Closed: Re: Relay selection for Ultrasonic signals

    If you do not switch a 900V signal, most of the small signal relays available on the market support at least 1000V between contacts (isolation) and can handle a 25MHz signal.
    But if want to switch a...
  11. [SOLVED]Closed: Re: Why are all reference sensitivity requirement of all bands different in WCDMA (UM

    The basic noise power density (kTB) of a WCDMA receiver is -108 dBm/3.84 MHz, at 290K (17°C).

    The 3GPP spec set various reference sensitivities in different bands function of potential interferers...
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    Closed: Re: Pulse distortion after amplification

    By definition an LNA should NOT be saturated in any cases.
    Reduce the input level into LNA, or use a higher IP3 device (with higher P1dB) which can handle higher input levels.
  13. [SOLVED]Closed: Re: Why is there always a shunt inductor for SMD (Surface Mount Device) antenna?

    Yes, series inductor is more convenient, but the matching can be done with almost any configuration.
    These chip antennas have awful internal impedance which require unusual matching typologies.
  14. [SOLVED]Closed: Re: Why is there always a shunt inductor for SMD (Surface Mount Device) antenna?

    This come from the theory. Small (or short) antennas are capacitive.
    So, for impedance matching they need an inductor (or more inductors) to "tune out" this capacitance.
  15. Closed: Re: Can you help me get S-parameter file of HJFET transistor

    Here it is...
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    Closed: Re: 1dB compression point and jamming signals

    P1dB of the LNA should be higher as possible, but keeping in the same time the LNA noise figure (and the cost) low.
    In an RF system, band filters could help the LNA to have lower P1dB, if the...
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    Closed: Re: Antenna pcb in commercial key fob

    https://infocenter.nordicsemi.com/pdf/nwp_008.pdf
    http://www.ofdma-manfred.com/wp-content/uploads/2012/09/23-MB.pdf
  18. Closed: Re: Recommendation needed for gain of antenna for a 2.4 GHz wifi extender

    RG58 and RG174 are very bad coax cables to use at 2.4GHz.
    Cheap RG316 from any Chinese vendor is better:
    ...
  19. Closed: Re: Which component can be a 2W LTE amplifier at 900Mhz?

    Only from the power amplifier you get about 40dB ACLR at 5MHz.
    The system spec of E-UTRA ACLR1 is 30dB, but in the LTE transmitter there are more ACLR contributors, not only the PA.
    With what you...
  20. Closed: Re: Which component can be a 2W LTE amplifier at 900Mhz?

    QPA2237 should work fine for your application.
    At 900MHz it needs about +13dBm at the input to get +33dBm at the output (with a lot of peak-to-average margin for an LTE signal).
    According to the...
  21. Closed: Re: Recommendation needed for gain of antenna for a 2.4 GHz wifi extender

    Gain of a coffee-can antenna is about 8dBd, which is equivalent with the gain of a (good) Yagi antenna with 5 elements.
    Size of the two antennas are pretty similar.
    Coffee-can antenna is easier to...
  22. Closed: Re: Recommendation needed for gain of antenna for a 2.4 GHz wifi extender

    I know that looks a bit ugly, but a coffee-can antenna for 2.4GHz is the simplest directive antenna (with proved good performances) that you can get for low cost.
    On the net you can find a lot of...
  23. Closed: Re: How to realize inductor from transmission line (micro-strip and CPW lines)

    The simplest microstrip inductor would be from a microstrip line without ground (the ground decrease somehow its inductance).

    The inductance of an isolated (no groundplane), high impedance...
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    Closed: Re: Spectrum analyzer range extension and usage

    Yes, high frequency spectrum analyzers use harmonic mixers and tunable YIG filters (Yttrium Iron Garnet) in front of them to remove spurious.
    Take a look to this video (from min. 43) and understand...
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    Closed: Re: Antenna and microwave business website

    So, you want to create a commercial website, but you are afraid that "strange" people will steal (without paying) that information and build military stuff? What about if they pay for that...
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