# Tag Info

## New answers tagged rf

0

I wasn't able to track down an equation, but the Transmission Line Design Handbook (Wadell, 1991) (sec.5.5.3) contains a table of optimal arbitrary angle miters for microstrip width to height ratios and bend angles. Here's a table giving the values (taken from here): and here's the bend diagram and corresponding equation, taken from Wadell: $M=\frac{x}{d}\... 0 Does this help: -$C_0$in the common collector Colpitts oscillator on the left has an extra varactor diode in series for auto tuning but, other than that they are identical. You might also look up the SA605 because it has more details about the oscillator that may prove useful to you. Colpitts Oscillators are commonly referred to as having "a tank" but ... 0 If I remember rightly, that cap is part of the circulating-current loop. You may view that circuit as a PI of form CLC, and you want some stepup ratio from emitter to base. So make the cap from emitter-base about 2x the other resonant cap. 0 Sounds like an interesting project. My approach would be to hack the dispenser rather than the refill. Look at what the dispenser does - actuates a motor or a solenoid presumably - and work on that instead. Reverse engineering the RFID is precisely what they're trying to guard against. -1 At 6 GHz you really don't have to worry about 45 deg corners. I'm going to look at this like a signal integrity (SI) problem. A square corner is going to add a bit of capacitance to the trace at the corner, which impacts Zo of the line. How much this affects your signal depends on the amount of capacitance added (which depends on the line width) and the ... 0 It's used to create a "bias Tee", which allows DC power to be delivered to the output port of an up-stream device, such as an amplifier or photodetector, while the RF signal retains proper impedance matching from source to load. That prevents creation of inter-symbol interference in a digital system, or standing waves on an analog transmission system. The ... 1 each via, with 1:1 aspect ratio of periphery : height, has 70 degree Centigrade thermal resistance per watt, for standard plated via at 35 micron (1.4 mils) plating. An aspect ratio of 2: 1 (periphery is 2x the depth of the hole) has 35 degree C thermal resistance per watt. 0 It sounds like you're doing everything correct thermally. Don't be surprised if it's still down on power when you fix all that -- you may still have electrical issues. You can test the thermal design, at least to some extent, by scraping off the solder resist around the chip on the back side of the board and soldering on a piece of brass or copper sheet, ... 1 My waveguide knowledge is a bit sparse. But here's the way I think it works. What you've shown on the left of your drawing is a classic quarter wave stub. This creates a 180 deg phase shift (90 deg out, 90 deg back) in the signal that's returned to the "T" junction. But, the waveguide section on the left is terminated in a short. When the RF reflects off ... 0 In high frequency electronics, a short circuit has the effect of total signal reflection. (It can be compared to what a mirror does with a light beam). So this short circuit will reflect all signal power back into the antenna. 3 I think your over thinking this. Outside of super narrow beam pattern horns or the like, 700Mhz is fairly forgiving. I don't see how a u.fl connector would have enough effect to matter. As long as your test cable is kept away from the plane of radiation, I don't see a problem. As for the connector, at that freq a 1/2 wave is 20cm(if your using 1/4 you ... 0 The long ferrite rods in old AM radios may be of use in focusing the Magnetic field. 0 at the scales involved the 125 KHz signale are basically magnetic fields, so to disrupt a card from 1m away you need to make a stronger 125KHz magnetic field in the proximity of the card than the card is making (or the same sort of signal level at-least), that's probably going to require large coils and strong currents. 1 look at the schematic, in the data sheet, for NE602 balanced mixer 0 An open/short/load calibration synthesises an accurate network analyser at the location of the reference plane. If you do not have the calibration standards that the VNA knows about, then you must enter the electrical characteristics (offset length for short, offset length and radiation factor for open) of the ones you are using. Then take the measurement ... 0 You need special software, tool, etc to operate your Bluetooth device however you want. Usually, these required components are supplied by the manufacturer of the chip used in the Bluetooth device. By the help of software, you can easily change the rf output power. To measure connection quality, you need a companion device that communicates with your ... 0 Why is the arc caused in the first place? Is it because of fringing capacitance (inductance) for open (short)? It's because the cal standards you used don't match the expected behavior of a nearly ideal open, short, and load exactly. Most likely either the open or the short has a small amount of distance between the SMA reference plane and the effective ... 1 L/c resonators must have a complete circulating loop. That 0.1uf completes the loop, while placing the lossy resister across a fine parallel Z --- the cap you added. 1 Your cap C6 closes the LC loop and becomes an impedance transformer with high Q LC filter with 44 dB gain or Q > 200 but then attenuated by 1k5 to -21dB loss. I bypassed 1k5 to measure the Bode Plot. If you followed my hint to use Falstad's filter analyzer, then you can make this with ideal switch and caps to compare with/without. from +44 dB gain to -... 2 All analog filters used in RF receiver frontends are in the class of Analog Infinite Impulse Response filters and, therefore, they can’t have stability and linear-phase properties at the same time. In your application, the signal has a constant envelope and all the data is stored in the phase of the signal. This signal is affected by so many parameters in ... 0 Phase shifts cause AM_PM conversion, and vice versa. Is that a problem for the data eye? Think about the data recovery needs, the ISI tolerance, and only then define the acceptable phase nonlinearity. ========================================== The best detector for bits are "matched filters"; if you have unknown phase behaviors, the ideal bit recovery ... 1 Note: you have your notation backwards from what I believe to be convention.$b$refers to the outgoing wave from the network and$a$refers to the wave incident on the network. That being said, the following will use your notation instead. When$\Gamma_g=0$, what is implied is that the source impedance of your generator at port 1 is matched to the ... 1 In a two port network (e.g. your quarter-wave transmission line)$S_{21}$is the transmission coefficient only if port 2 is matched. This is an important distinction that trips up a lot of people. Let's define the reference impedance of port 1 and port 2 of the transmission line as$\sqrt{2}\Omega\\$, the same impedance as the transmission line. Then the ...

0

The frequency sweep pulse compression: Both generating the transmitted pulse and performing the compression in the receiver is possible and was also practical with analog circuits. Chirping radar was popular before real time digital signal processing with tens of MHz sample rate. The special filter needed was a dispersive delay line which caused steeply ...

2

In the absense of information in the question, this document suggests that the 865 to 867MHz band is used in the UK for RFID purposes, and it's likely many other territories around the world use the same frequency range for the same thing. 1) Transmitting power means the power the transmitter is rated or measured to produce. It will often be the power ...

1

You can use the GPIO pins on the Pi to set the address and the data to send. The HT12E uses 8 address and 4 address/data pins to select the address and data. You'll need 12 GPIO pins from the Pi to drive the data and address pins. The Pi has 25 GPIO pins, so that's covered. The Pi operates on 3.3V. If you power the HT12E from 3.3V, then you'll have no ...

0

The TI reference design should include a layout. My advice is to copy that layout exactly for your first iteration and test it. Pay special attention to preserving the spacing between the antenna poles and the reference planes alongside (but not beneath!) them. If it works well enough, go with it (it likely will.) If not, hope is not lost. You can adjust ...

Top 50 recent answers are included