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9 votes
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Synchronized two frequency source seems to have phase drift

The problem is that AWGs are often, well usually, binary based internally. The attitude of many AWG manufacturers is that once you can approximate your desired frequency to the nearest μHz, it's '...
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  • 140k
7 votes
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Analog television: What is the difference between the first IF and second (demodulated) IF?

It's helpful to include a link to the datasheet even if, as you note, it doesn't explain the circuit operation. Why is the video carrier frequency 38.9 MHz but the audio 33.4 MHz? On-air the audio ...
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  • 2,605
3 votes
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Designing GPS matching network with TESEO and chip antenna

Since you're using the LNA and SAW filter, you need to include the series capacitors, but they don't play a role in impedance matching. Why? The reactance of a 120 pf capacitor at 1.5 GHz is less than ...
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  • 2,995
2 votes

Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its bluetooth signal?

Sure you can. Cut the trace antenna and solder a suitable 50 ohm 2.4ghz tuned antenna to it, and ground. But should you? You may find that you have little to no performance increase. The trace antenna ...
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  • 70.7k
2 votes

Noise factor in homemade software-defined GPS receiver

Can your SDR measure signal strength at specific frequency? If so a simple test is to measure the noise power at a frequency where no signals are present (maybe place Antenna/LNA in shielded box). ...
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  • 190
2 votes
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Frequency Counter Input Impedance

RF has signal integrity issues at 1 MOhm above 50 MHz due to resonance. The low impedance dampens the ringing from inductance and self capacitance of cable or reflections from longer cables from ...
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1 vote
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Simple Diode Mixer Help

In an unbalanced single diode mixer it is important to provide a DC path through the diode to ensure that the bias conditions are correct. There should be significant conduction occurring during the ...
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1 vote
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Antenna feed trace keep it short or long?

Optimize positioning of the antenna on the PCB: it should be at the upper right corner, not halfway up the right edge. Minimize bends and jogs in the microstrip transmission line. Every discontinuity ...
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1 vote
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How to choose a sweep range for a known and unknown device with a VNA?

With just a VNA, you're only able to check the impedance match of the antenna, not its radiation pattern, gain, or other characteristics. If you know the intended frequency range for use, there's no ...
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  • 2,995
1 vote

Diode SPICE data accuracy at high frequencies?

You cannot extrapolate Spice data where geometric impedances affect the conductance and junction capacitance assumptions in the datasheet. "Measured at a LO frequency of 9.375 GHz, with an IF ...
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1 vote
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Does an antenna have to be impedance matched to its transmitter circuit or the transmission line from it?

Does an antenna have to be impedance matched to its transmitter circuit or the transmission line from it? If the t-line is short i.e. less than one-tenth of a wavelength of the carrier frequency, ...
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  • 378k
1 vote

Is this circuit measuring the electrical field?

It doesn't measure electric field. It show what the 2 diode rectifier happens to rectify to the sub-milliampere galvanometer. The size and the connection wire length of the galvanometer also affects ...
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1 vote
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Interaction between half wave dipole and power supply lines in 433 MHz RF module

If your cable with signal, power, and ground leads runs horizontally, at right angles to the vertically-oriented dipole antenna, you needn't worry too much about interaction with the RF field. ...
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  • 2,995

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