Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [magnetic-loop]

30 questions
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Stealth HF station setup advice

I need some advice on setting up my first HF station in a somewhat restricted townhouse community. If I had a detached house with a backyard I’d probably already have everything setup. But with this townhouse I keep second guessing what to…
ifletch
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Real world performance of magnetic loop antennas?

I was investigating about magnetic loop antennas. In a paper about them I found some bold claims: and This almost sounds too good to be true, considering a lot of us hams are surronded by city noise and this paper claims the noise would be much…
hjf
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Why are there differences in antennas that depend on electrical component and magnetic component of a radio wave?

I understand the idea that when we are targeting the electrical component of the radio waves we need to have some form of a linear conductor that receives the electrical component, this creates a current in the circuit and thus induces a signal.…
Bartha
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What's an appropriate core material for a loopstick antenna?

A loopstick antenna, if you don't know, is a coil of many turns around a high permeability core. They are frequently encountered in AM receivers and look like this: This particular example is actually two antennas on one core. What type of material…
Phil Frost - W8II
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How does a Large Loop Antenna work physically?

I am learning about loop antennas at the moment. I read that the response of a small loop Antenna is proportional to the rate of change of magnetic flux through the loop which causes a uniform current distribution in the loop. This would be…
kinu
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Do short waves pass through or reflect off concrete buildings?

I live in Moscow, Russia and use DIY indoor magnetic loop antennas to listen amateur radio. Recently I received quite strong signals from Italy (20m, IV3UTV) and Slovenia (40m, S51CK), both operators are ~2000 km from me. One thing I don't quite…
Aleksander Alekseev - R2AUK
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Using a loop antenna on a harmonic of the intended antenna frequency

I bought a MFJ 1786 Magnetic Loop Antenna, which is made for 10 thru 30 MHz. It is not meant for use on 40 meters. The antenna has its own built in tuner. I have a Yaesu FT-890AT with built in antenna tuner. So my question is: could I tune the loop…
jim
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Why does an "electrically small" antenna have narrow bandwidth?

Reading this interesting piece on magnetic loop antennas, the author explains that a magnetic loop has great efficiency even at small size, but the the price you pay is very narrow bandwidth. Why is this? It seems counter-intuitive (and miraculous)…
bcattle
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Debugging SM0VPO's spiral loop antenna build

I had built SM0VPO's spiral loop antenna. And here it is. Recently I got myself a NanoVNA to see how finnicky it is to be tuned with that poor man's tuning cap. I brought it from 12 MHz into the 14 MHz 20 m band range by cutting off the extra wire…
Gunther Schadow
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High-Z RF amplifier for magloop RX vs Q-factor

I've noticed that increasing load on magloop reduces it's Q-factor, it becomes less selective. Traditional way to approach this is reducing size of pickup loop, or alternatively, using transformer. But is it possible/known approach to build FET…
BarsMonster - R2AYN
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Optimising a small magnetic loop with 1:1 SWR but little radiation

I'm trying to build a small magnetic loop for 5W on at least 40m - 20m following ideas of G4ILO's wonder loop. For this, I'm using coax with a ~2mm copper core and ~1mm spacing to the braid (see 1st image below), with braid and core connected on the…
user885
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1 answer

Are the voltage ratings on Vacuum Variable Capacitors RMS or Peak

I'm building a magnetic loop antenna and was wondering if the voltage ratings on the vaccuum variable capacitors I have are: RMS Peak to Peak Peak other? I have been looking at this wonderful magnetic loop calculator to help choose a capacitor…
Arthur
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Is a magnetic loop antenna a good option for those in an apartment?

Are magnetic loops a good choice for those living in apartments or condos where a permanent installation is often not an option and the operator still wants access to the HF bands? Why or Why not? Edit: Building is from the 1800's, the roof of this…
hehe3301
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Magnetic loop antenna : loops vs selectivity

I've built 2-turn magnetic loop RX antenna using 5 meters of 6.5mm copper tube. I was able to tune it with a variable air-spaced capacitor in the range of 1.8-10Mhz, but I noticed that as tuning frequency goes to 7MHz and above - selectivity gets…
BarsMonster - R2AYN
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Magnetic Loop Antenna with RFI Choke

Because of space limitations, am purchasing a magnetic loop antenna. Because of needing to move the antenna around, do i need a RFI choke in the feed line?
user13930
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