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4

Your phone has NFC turned on so it is trying to read any NFC devices that might come into range.


3

It depends how accurate a calibration you need. The open standard in the cal kit has some parasitic capacitance. When you use it to calibrate a network analyzer (VNA) you'll specify this (and a couple other parasitics) to the VNA to get the most accurate calibration. It's usually possible to make a short standard that is closer to an ideal short than the ...


2

My bet is it's 2 watt. The 100 ohm resistor is listed, but there is probably more than one (or it would be a 100 ohm load) and the resistor is most likely tied to the case, when they are tied to a heatsink, you can run more power through them if the temperature is kept low. The most important thing would be to follow the temperature rating and keep it below ...


2

These 433 MHz transmitters use OOK modulation (also called ASK), making the transmitted signal look like: So the transmitter is simply switched on (1) or off (0). Most 433 MHz receivers will "filter out" the 433 MHz so we're left with the blue signal. When no signal is received for some time, most receivers will try to decode a signal from the noise they ...


2

The easiest way is to use TDR (Time Domain Reflectometry). If you believe that the coax is 50Ω and you want to verify it, you put 50Ω connectors on either end, connect one end to the TDR and terminate the other end with a 50Ω resistor. If you're right, the TDR display will be perfectly flat. If not, the steps on the display will tell you ...


2

When you connect to a 50 ohm device, you usually make the connection with a co-axial connector. Alligator clips, and the tails of wire leading up to them, will introduce a section of higher impedance. Whether this makes a negligible or a significant difference depends on your operating frequency, and the length of the tails. If you keep them well below 1/...


2

Stolen from: https://www.edn.com/design/test-and-measurement/4424529/So-you-think-you-understand-transmission-lines- But anyways, that's the impedance of some transmission line that's open on the other end. You can see it decreases in impedance initially, which is the hallmark of a capacitor. Then it sharply decreases and starts going back up, which is a ...


2

For RF transformers/baluns, the inter-winding capacitance can play a big part in reducing common-mode signals between unbalanced input and balanced output. A 1 pF inter-winding capacitance may not seem that much but, at 1 GHz, it's an impedance of 159 ohms. So, if you don't ground the centre-tap your balun won't be working as effectively as it can do ...


2

How are my chances to modify this device to output drastically more power? The device is a transceiver and the transmit/receive arbitration circuit is inside the chip and therefore you cannot put an amplifier in the antenna feed (unless you are highly skilled and have access to good equipment) because it'll stop reception of the RF signal. Plus, adding ...


2

By reading some application notes, I discovered, indeed, that the 4-port S-parameters measurements file is meant for creating a model of the transformer, and it can be used with a simulator directly, such as Genesys or ADS. Those are expensive tools unavailable for hobbyists, but I also found the free and open source Qucs simulation supports n-port S-...


1

The fundamental frequency is determined by the commutator switching speed (which varies with motor rpm), but the rf produced by arcing can go up to GHz frequencies. Here's an example:- The blue line is before adding ferrite cores to the motor leads, the green line after. At lower radio frequencies (below 100MHz or so) small capacitors connected from each ...


1

Without more information(competing signal levels, distance to target, etc) I can't really give specifics. But here goes... I would first try a good directional antenna. There are plenty of 2.4Ghz Yagi antenna available, I would try something with a 9dBi to 18dBi gain to start with. Then you'll want a GOOD cable to connect it to your board. This means ...


1

You did not specify your requirements, but if you need a low speed, you can use the following tips: Use the lowest speed possible Use the maximum power setting Use the external antenna shown in the pic Than check how many packets are arrive successfully. If this is 0, you are mostly out of luck, but if it is higher than 0, than you can use a protocol (I ...


1

Assume your IP3 is +20dBm. The 3rd order distortion drops 30dB, per 10dB input power reduction. Thus -10dBm input RF power drops the distortion by 3*(+20dBm - (-10dB)) or by 90dB below the IP3, or to +20- (90) to -70dBm; [ note my Initial Error in computing the distortion level: had gone 90dB below +10dBm and that is wrong; should be 90dB below the IP3, ...


1

in this book you can find Matlab implementations for FDTD. It specifically used for microstrip circuits but it might help you. I hope this helps.


1

It's rated for 2W, it should do 2W unless they note caveats. I'm not even sure why they felt they had to include information about the resistor -- possibly because they needed it for mil-spec-ness. If you're worried, get one and put 10V DC on it. You should see a 200mA current flowing, and the thing shouldn't burn up or otherwise change characteristics ...


1

No, the transmitter's data pin isn't interpreted as a voltage, but as a zero or one logical signal....binary data. Similarly, the receiver's data pin is a logic signal. It will swing from ground (logic zero) to Vcc (logic one). You might think that such a transmission system is similar to a UART function. You might actually get it to work this way, but ...


1

The magnetic field around the wire corresponds to the current in the wire. More correctly, the magnetic field in the space between the wires corresponds to the current loop formed by the source, one wire, the sink, and the other wire. The electric field between the wires corresponds to the voltage between the wires. If there's 10v measured between the wires,...


1

The way I did this was to use pre-made boards that use a circuit board j-pole antenna, lowest power setting and the highest speed. Once triggered they would ping-pong each other once every 2 seconds until the primary failed to receive 5 pings, at which point it would sound an alarm. This averaged out to be about 10 to 15m, which was plenty accurate for my ...


1

Your reasoning is almost correct. In the step where you take the limit of the \${E_b}/{N_0}\$ equation, you're making a mistake when applying L'Hôpital's rule. It should go as follows: $$ \lim_{C/W \to 0^+} \frac{E_b}{N_0} = \lim_{C/W \to 0^+} \frac{2^{C/W} - 1}{C/W} = \lim_{C/W \to 0^+} \ln {(2)} 2^{C/W} = \ln{(2)} $$ Your problem arises when you take ...


1

A typical RF mixer does not multiply the RF signal with the LO (local oscillator) signal. Instead, the signal polarity of the output depends on whether the LO is negative or positive: when the LO is positive the output signal is the same as the input signal (up to some gain) and when the LO is negative, the output is the same as the input but with an ...


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