All Questions

Is it true that the reactive part of the impedance of a half wave dipole doesn't change along the length whereas the resistive part does change ? Because the AC current and voltage have the same ...

For a straight wire antenna such as a half wave dipole, is it true that the antenna is resonant for those particular frequencies only where an applied AC voltage results in an AC current which is in ...

I'm trying to get into SDR and was planning on buying an RTL-SDR. For an antenna, I was thinking of using an old set of bunny ears I have lying around. However, I first want to make sure that they'll ...

I have been under medically supervised treatment for the past few years. I have been on heavy meds. I presently am showing signs of improvement from cognitive issues which were troubling me. I ...

I need to estimate the signal delay through the 1:4 Guanella balun shown here: Is the delay simply the delay through the winding on CORE1 or CORE2? For example, assume each winding comprises 0.1-m ...

I noticed that watches with GPS signal receivers made by Seiko and Citizen have an airplane mode. If it's a GPS receiver, it shouldn't cause interference, right?

Is there any kind of directional coupler device such as you find in a SWR meter that only allows traveling AC waves of one direction to pass which i could use to block the reflected wave from my badly ...

Standing waves are seen on a transmission line when for example there is a change in impedance and a transmitted wave is reflected back from one end and then the incident wave and reflected wave ...

If i were to use a passive transmit coupler to connect two transmitters of equal power output to the same antenna, and connect one microphone to both transmitters, and then transmit on both at the ...

Actual standing waves have nothing to do with causing the output device in a transmitter to fail, in fact it's the reverse or reflected current which helped to create the standing waves which is ...

When using a balanced antenna such as a half wave dipole, with an unbalanced feed line such as coax, an RF choke can be used to block RF current emitted by the transmitter from splitting up at the ...

I am just starting to learn CW, and for practice I have been recording and transcribing repeater identifications that I hear. This is what I heard today: DE W9KIC/R BBG What is the meaning of "BBG"?

Please help me identify this piece of equipment. It looks military spec, but don't know anything about it. I want to look up some history about what it was used for. Here are some photos.

I am using a Pixie transceiver, giving 1 W power and 7 MHz frequency. A 40-meter band dipole antenna, providing 5 dBi gain at high angles, has been designed and connected at the output of the circuit ...

Antenna theory it seems is always described assuming that the transmitted or received signal being talked about is a pure sine wave usually at the resonant frequency. Standing waves for example are ...

I recently got my GMRS license from the FCC, and I wanted to try out a couple radios for hiking and emergency communication. I have two tenway UV-5R pro radios (these do have an FCC ID) that are set ...

I read in some text books that E-plane is formed by taking constant azimuth angle and scanning elevation angle from -90:90. H-plane is formed by taking a plane perpendicular to E-plane. What is ...

I'm trying to understand way which Frequency Mod block works in gnuradio. According to my intuition there should be at least two inputs: signal to encode base frequency / carrier signal Instead ...

Context I'm launching a series of weather balloons as a capstone graduation project. Right now I am in the process of building the payload. I have been going over the different components of the ...

I'm trying to hide some message in the video file (for the purpose of puzzle game). I was going through https://wikipedia.org and https://sigidwiki.com I found couple of interesting protocols (FLEX ...

I recently built a SA612 mixer for HF reception. I used an USB-frequency oscilator to shift the incoming frequency up by 28.8 MHz. I used a random wire antenna outside my balcony and connected it to ...

I am currently a master student doing TPU-based BLE stretchable antenna, and I have an interview for an "Extremely Large Antenna Arrays (ELAAs)" PhD position. can anyone give some tips/advice on how ...

In theory when i need to shift some frequency i just multiply that signal by some sin or cos wave with the right frequency and than apply LPF or HPF. But when there is a wideband complex signal with ...

I am trying to homebrew a cobweb antenna and need some help understanding the guanella balun used as described here: http://www.karinya.net/g3txq/cobweb/ This author used RG316 coax around the ...

For transmit, the voltage at the center of a dipole not cut in the center and fed with coax and a gamma match is zero in the center at the resonant frequency. This is why apparently a 'plumbers ...

I made a small yagi, with the driven element being a coil loaded dipole. What is the effect of coil Q in this situation? The coils I built are 18 turns of 1.2mm enameled wire wound tightly with a ...

I have a hackrf one sdr, which i use to transmit test signals. I am using ISM bands, so I can omit transmitting my callsign, checking correct sub band (FM, digital) etc. And one of most interesting ...

I am trying to use Gnuradio to build QPSK transmission with satellites simulation for educational purposes. Unfortunately, I am unable to add new blocks after "find blocks" (blue magnifier icon) ...

While monitoring the 40-meter band (among others) throughout a typical day/night as propagation changes I have noticed there are often bands of very low noise (black area) and others with much higher ...

When I took the Amateur Radio Technician Exam, I was given a callsign upon passing the test. How does the FCC create that callsign? Is it completely random or do the letters and numbers have meaning?

In amature radio, users can use what is called a phone patch to enable them to use a phone to establish connection to another party or user. Phones are usually two wire and dont lend themselves to ...

There are a lot of videos on YouTube from people who have built high voltage sources and are sending electric arcs from one place to another. Although they have no intention to emit radio waves, they ...

Is there considered an ideal / optimum length for a doublet for use on 160-10 meters when fed with open-wire feedline and a balanced tuner in the shack?

For older receivers with a fixed (crystal?) audio filter for CW, what is the usual center frequency of the audio bandpass of the filter? Or cut-off frequency for low-pass CW filters? For newer ...

in GRC for this source block ?

I am an ELECTRONICS final year student and I am working on a project, "Full Duplex Radio On a Single Frequency". So is it possible to design such a project. If so then give me the idea about it, how ...

I'm looking for a circuit topology that has unity gain, a 50 Ohm resistive input impedance, a 50 Ohm resistive output impedance, and here is the kicker, at least 60 dBm OIP3 over a 2 - 30 MHz HF ...

I built a center-ish loaded coil-shortened vertical. The lower radiator is 3 meters, then the coil, then 5M more radiator, like this (Early prototype with shorter radiators and no covers for the coil ...

I'm populating a CSV file to import into CHIRP. In the documentation, there's a list of CSV columns. However, that list doesn't cover URCALL, RPT1CALL, and RPT2CALL. Can anyone tell me what those ...

I understand that an antenna is resonant at the frequency where the capacitive and inductive reactance cancel out to 0. Only the resistive impedance remains at resonance. Does this mean that the ...

I am building an out building ham shack. I am planning to install an 8 foot ground rod for the antenna. Does the radio require an additional ground to the rod as well or do I need to install a ...

The ferrite Rod is a reasonably effective Receiving Antenna for LW MW and Lower HF spectrum .It is well known that a ferrite rod is much more effective than an air cored coil of the same dimensions ....

In an earlier question, there seemed to be some surprise when I (indirectly) asked about radio modes accessible to a blind operator. First question: So how do blind hams operate? If I were to be ...

Assume a computer (Raspberry Pi, Mac, etc.) is used to connect to a radio (HF transceiver, etc.) via audio cable(s), USB port, or GPIO, etc. What contemporary computer DSP/digital modes, of those ...

What is the limit of a transmitter in the GSM1800 band (~1830 MHz)? The ETSI GSM specification states a limit of -47dBm between 1GHz and 12.75GHz (https://www.etsi.org/deliver/etsi_gts/05/0505/05.00....

I know the major components of rectenna should be Receiving antenna - Patch Antenna Matching circuit Low pass filter Rectifier - Schottky diode but I could not visualize how can we put all ...

I apologize if this question is a little out of scope for the amateur radio stack exchange but I feel like it fit better here than over in any other forum. I have successfully parsed raw PCM data out ...

At the bottom of webpages in the advertisement swamps I keep seeing this image of an antenna, accompanied by an offer that I won't be clicking on. But the antenna itself looks quite intriguing. It's ...

How can I make circutes which can send and recive AM wave ? I want to send my Voice but i don't the circute which can transmitter and recive

I am using a Folded Dipole which I bought when I first got my General License. It was advertised as an all band antenna. My results with it were less than the claims made by the makers to say the ...