# Questions tagged [wave]

May refer to an electromagnetic wave (such as a radio wave) or the PCB manufacturing process of wave soldering.

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73 views

### Precision amplitude 600kHz square wave generator

I'm looking for a circuit that creates a precision amplitude square wave of 600kHz (50% duty cycle). The amplitude of the square wave needs to be 3Vpk-pk +/-10mV, but can be DC offset. The output of ...
103 views

### Why don’t radio waves interfere with each other like other waves? [closed]

I know this question has been asked before, but I still don’t completely understand. I understand that different stations are given different frequencies, but waves are able to interfere with each ...
108 views

I was wondering what would be the best waveform to generate for a phased array short range imaging radar? Square, sine, etc. Also what frequency would be best to operate at for the carrier wave given ...
117 views

### Create electromagnetic waves using Lc tank circuit

Electromagnetic waves are produced by the motion of a dipole and suppose we have top and bottom points then the negative and positive charges must oscillate between those 2 points. However an LC ...
81 views

### Is it possible to generate a sine wave formula using values from an array?

so we have an Arduino code which includes an array, is it possible to make those array disappear [in the code] and instead formulate a sine wave formula for those [array] to make the output in sine ...
24 views

### What is the phase of the impedance at each point on a resonant center fed half wave dipole?

Everyone knows that for an ideal center fed half wave dipole operated at resonance, the impedance at the center is 73 + j0 ohms. The impedance at any point on the antenna is determined by the ratio of ...
30 views

### power waves and scattering matrix

I have some doubts about the concept of power waves used in the description of the scattering matrix of an N-port component. In particular, I was wondering what is the most general and correct ...
15 views

### Difference Amplifier to retrieve sine wave

I have built the following summing amplifier circuit from a Fourier approximation of x(t)= 0.143 + 4/π ∑((sin⁡(2π(2k-1)ft)/(2k-1)). I am now trying to retrieve a sine wave from the output of the ...
30 views

### Friis transmission equation: how do I consider power loss along other directions?

I do not understand a basic concept about Friis transmision equation between two antennas: where Dt and Dr are the antenna directivities (with respect to an isotropic radiator) of the transmitting ...
33 views

### Far field radiation and spherical waves

I have a basic doubt about electromagnetic waves emitted by a certain source. Depending on the shape and on the physical properties of the antenna, its electromagnetic waves may have different ...
70 views

### Separating odd and even pulses in a pulse train

How would one go about separating odd and even pulses in a pulse train and displaying them using LED indicators? A schematic would be of great help.
37 views

### How to half frequency of triangle wave

I wanted to know if there is a method/circuit to half the frequency of a triangle wave, in the same way a flip flop can be used to half the frequency of a square wave. Any help would be appreciated ...
66 views

### I'm having issue getting thick tin-lead 63/37 solder on Alloy 42 lead frame

I'm using Kester 2235 flux and using robotic solder dip so heights are static. I'm measuring thicknesses using x-ray fluorescence, they keep coming up very low. Should I be using an initial scavenge ...
49 views

### Does anyone know how can I deduce this formula for frequency from this sawtooth generator?

[ I know that this formula is correct, but I'm not sure how can I deduce it. Can anyone help me? Thanks in advance!
126 views

### Scope says 59.9 Hz .. yet I can't measure turntable speed

I needed to measure a turntable's number of revolutions per minute, but didn't have any incandescent lamps around. So I rigged an LED to an ESP8266 SOC and programmed it with delays to output a 60hz ...
71 views

### how to find the frequency of this nonperiodic composite signal?

I'm new to electrical engineering, sorry if my question sound dumb. Below is a nonperiodic composite signal plot: As you can see this is a nonperiodic composite signal in 1s and I know that if the ...
62 views

### Is the amplitude of a sine wave increasing or decreasing in this phase?

I'm new to electrical signal, sorry if my question sounds dumb. Below is a picture from my text book: It says a sine wave with a phase of 0° starts at time 0 with a zero amplitude. The amplitude is ...
25 views

### How do you model acoustic waves underwater that are generated by an Nd:YAG laser?

In this paper on page 84 they show the following experimental setup: The array of receiver hydrophones are set up to record sound pressure waves sent by the transmitter hydrophones. In Figure 6....
122 views

### How to demonstrate mathematically the conditions of reflection in transmission line?

We are all taught about transmission lines and its associates -- characteristic impedance, reflection, standing wave, etc. It is well known what happens when a transmission line is terminated with ...
44 views

### Spherical waves in far field region

in my antennas book (I do not put its reference because it is not in english) it is written that, at high distance from the source, the electromagnetic field radiated by it is a spherical wave. This ...
26 views

### Radiation pattern and propagation direction

I have a basic doubt about how to read a radiation pattern. Let's consider precisely the power pattern: it represents how the power is distributed along all directions in space. For instance, this ...
27 views

### Elliptical polarization and waveguides

It is known that a generic harmonic electric field which propagages in free space has an elliptical polarization (if you want to read the proof, look at this, slides 72 - 99). My question is: what ...
39 views

### What are the chain reaction that create the electromagnetic wave?

From my very limited knowledge I know that an electromagnetic wave is created by some chain reaction of accelarating/oscillating electric and magnetic waves, I also know about how the electromagnetic ...
203 views

### Why should signals in circuits propagate much slower than the speed of light?

I've read a couple of other topics (such as this one and this one) about the lumped circuit abstraction requiring that signal timescales (i.e. the period of the highest frequency signal component) be ...
72 views

### Why are E and B field in phase in far-field electromagnetic wave propagation?

I am very frustrated with the fact that the E and B field of an EM wave are in phase in the far-field case. Before I get into this question I am letting you know that I already read this link related ...
58 views

### Why/How alternating currents through coaxial cable do not interfere with each other?

I know that cable TV use coaxial cable with alternating current frequencies varying from 5 MHz to 750 MHz. Why/How a alternating current of, for example, 5 MHz , 10 MHz, 20 MHz, 100 MHz, 300 MHz, 500 ...
52 views

### Waveguide excitation through coaxial antenna

let's consider a waveguide excited with a coaxial cable antenna: You may see that this structure is sized with a distance between the antenna and the plate equal to $\lambda/4$. My professor has ...
67 views

### Wave soldering of PCB with Through hole and test points. Masking test points

I want to do wave soldering for the through hole components. All through hole components are top side of PCB. Bottom side of PCB has only test points. How do the assembly house mask the test points ? ...
91 views

### Electromagnetic waves antenna via microcontrollers (Transceiver and receiver)

I have two Arduinos: Mega and Nano, and 2 steel pieces of wire as antennas which I stuck directly in the pin slots. I've setup my Mega2560 to generate an alternating current on one of its pind (PWM ...
63 views

### Why does lumped discipline not hold as dimension approaches operating signal wavelength?

I'm studying some basic introduction to the lumped matter discipline on my own. I completely understand where the first two constraints come from (i.e. lumped matter can only interact through their ...
4k views

### Why does 1/4 wavelength have a ground plane and 1/2 wavelength needs none?

Why does 1/4 wavelength have to have a ground plane and 1/2 doesn't? I know that an antenna that has half a wavelength does not need the ground plane (example a dipole antenna) and when using a ...
130 views

### Standing waves in Dipole antennas

I'm relatively new to antennas. In most of the textbooks, it is said that we want to minimize standing waves in the transmission lines by matching the characteristic impedance of the line with the ...
128 views

### Looking to generate 25 Hz square wave at about 90 V AC

I am looking to build a square signal generator tuned to ~25 Hz at a voltage of ~90 V AC that can output ~400 mA. I've searched around the internet and tried a few things but I've had no luck. My ...
27 views

### Based on $f(f) = \phi_{\beta} \; \land \; f(t) = |\beta_u|$ determine type of oscillator

Imagine the below characteristics of feedback circuit in sinewave oscillator are drawn: $$f(f) = \phi_{\beta}$$ $$f(t) = |\beta_u|$$ Based on the characteristics, how can I tell: Which type of an ...
47 views

### Non-sinusoidal waveforms: relationship (resistance, capacitance)$\xrightarrow{\text{affects}}$ (amplitude, frequency)

During the laboratory we have analyzed the following two non-sinusoidal generators: square-wave generator triangular-wave generator Sadly we didn't have enough time to complete the last task. My ...
99 views

### How to make a sawtooth waveform look less like a staircase (DAC)?

I am making a 4-bit digital-analogue converter using an adder circuit with four inputs. Each input is a square wave of a specific frequency. The output of the DAC is meant to be a sawtooth waveform ...
68 views

### Can the 1D wave equation be recreated in a conductive wire?

I am ignorant of EE, but not the wave equation, so bear with me. The (scalar) wave equation $d_{tt} - c^2d_{xx} = 0$ describes the displacement (and velocity) of some medium through space and time....
635 views

### What would cause a square wave to become rounded?

I have a square wave going through a thousand feet of cable. The cable has $120 \,\Omega$ characteristic impedance. I measured the capacitance and inductance of the cable and they are pretty close ...
43 views

### Magnetic field expression in a rectangular waveguide

I was reading the chapter of Fundations of Microwave Engineering (Robert E. Collin) about transmission lines and waveguides, and I have a question about the electromagnetic field in a rectangular ...
1k views

### Is there something as common frequency?

Let's say I have following three sinusoidal waves. ...
18 views

### Evaluation of Dominant Mode in a Circular Waveguide

I was doing the analysis of a circular waveguide (precisely, a wave guide with half - circular section of radius a, as shown in the following picture, and in which the shell is a Perfect Electric ...
16 views

### Error % for readings of average-sensing multimeters

Question: What is the error % in reading the voltage of a Square wave (1 Vpp) with an average-sensing multimeter with a half-wave rectifier, compared to a TRms multimeter The answer seems to be 11.1% ...
60 views

### Geometric spreading of an impulse antenna

I am new to radar and curious about the geometric spreading in free space. I set up an air-coupled antenna about a half meter above the ground, with a large PEC on the ground. Then I adjusted the ...
46 views

### Propagation Constant Expression in a Transmission Line

let's consider a generic transmission line: Its wave vector Kz is equal to: where Then, I read also that it is true that: where does this relation come from?
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### Interface Conditions between Dielectrics inside a Waveguide

let's consider a general waveguide with two ideal dielectrics inside it: Let's consider the interface condition about the tangential electric field: Generally E = E(x,y,z), where z is the axis of ...
152 views

### Coaxial Cable Resonance

let's consider a coaxial cable of length L and see what happens at port 1 when port 2 is left open. Let's consider what is written on these slides: 1) I do not understand the reason of this graph. In ...
118 views

### Frequency dependence of S21

I have done a measurement with a vector analyzer in which I have connected a certain coaxial cable to the two port of the instrument. Precisely, I have got a measure of the phase of S21 of this type:...
43 views

### how to reduce signal noises

I am trying generate guided waves on simple metallic plate through piezo-ceramic material, I place two piezo on the surface of the plate at the different location and through Arbitrary pulse generator,...