Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [bandwidth]

Questions about bandwidth used by various modes, theoretical questions about bandwidth, and questions about other amateur radio aspects of bandwidth.

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Why do folded dipoles have greater bandwidth than ordinary resonant dipoles?

This is something I've read in passing, but never encountered an explanation of why. For example, Wikipedia says: Another common place one can see dipoles is as antennas for the FM band; these are folded dipoles. The tips of the antenna are folded…
Phil Frost - W8II
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What are the relative bandwidths of the amateur bands?

While I was operating on 40 m for Field Day, I noticed a higher SWR than when I first set my antenna tuner for the band. This happened, of course, because I was in a different part of the band, but I hadn’t done enough HF operation to expect the…
Kevin Reid AG6YO
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Key CW on zero crossings - zero bandwidth?

I remember being surprised to learn that a CW signal has a bandwidth (albeit small), but when I thought it over, it made sense. Essentially, we are modulating the carrier with a low frequency square wave. This would explain key clicks: a perfect…
Dominick Pastore
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Why does the FCC put restrictions on symbol rates?

This answer claims that Mostly, on HF, the FCC has chosen to limit modes of transmission and symbol rates rather than bandwidth Why does the FCC limit symbol rates?
Geremia
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Do FCC regulations limit digital data rate?

Are there FCC regulations that specifically limit digital data rate on the amateur bands? Are there any recent or proposed changes? If so, what are they specifically?
Phil Frost - W8II
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Moon->Earth 433MHz link achievable digital bandwidth

Let's assume we have the following situation: Transmitter on moon orbit (distance from earth ~400'000km), around 433Mhz. Transmitter power 1W, antenna gain 10dB, circular polarization. Steered to point to earth. Receiver is on Earth. Antenna is…
BarsMonster - R2AYN
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Why are radio frequency ranges aligned on multiples of 3?

Why are the radio bands organized by multiples of three? For example the HF band is from 3–30MHz and UHF is from 300–3000MHz. Why not multiples of 2? Or plain powers of ten?
natevw - AF7TB
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Why do the ham radio bands get broader with increasing frequency?

The ham radio frequency allocations tend to comprise a larger frequency range for increasing frequency (also see this plot). For example, the 40 meters band is from 7,0 to 7,2 MHz, thus 200 kHz, while 23 centimeters is from 1240 to 1300 MHz, thus 60…
koalo
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Is the bandwidth of an LCR resonant circuit independent of the capacitance?

Is the bandwidth of an LCR resonant circuit independent of the capacitance, if the inductance and its series resistance are kept the same, and the Q is high? This question and the calculation associated with it were originally posted by a radio…
Harry Weston
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How does signal strength relate to bandwidth?

Let's say I have a 25 W transmitter. First I transmit some SSB signal with 2500 Hz bandwidth (no audio compressor is used, etc...). Then I transmit a BPSK31 signal with at most 100 Hz bandwidth using the same power. Is it accurate to say that…
Aleksander Alekseev - R2AUK
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Which band will I be authorized the most bandwidth?

Lets say I want to do a bit of experimenting with some high bandwidth uses for transmitting data, high quality voice, etc. Which Amateur band will give me the maximum bandwidth, and what is the maximum width?
Skyler 440
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Why ferrite-core transformers are wideband while air-core are not?

While experimenting with end-fed antennas I've made two 1:49 transformers. The first one has an air core, as shown in the article by John, M0UKD. This transformer doesn't even work as a transformer until you add a capacitor in parallel to the load.…
Aleksander Alekseev - R2AUK
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Is there a legal limit to the bandwidth of a signal used in the amateur bands?

While a normal voice channel is ~10kHz-15kHz in bandwidth, some digital modes can be significantly wider. Are there any legal restrictions on how much bandwidth I could use for amateur radio communications (e.g. video chat over ham radio)?
Stack Tracer
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Does the wire/conductor size of all the elements affect antenna bandwidth?

Does the wire diameter of the reflector and the directors of a beam antenna affect the bandwidth or is it only the driven element diameter that has this effect?
Mein Tenah
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Receiving commercial / public-safety on a general-coverage HAM transceiver

I have an ICOM-7100 that I've installed in my mobile as my primary (nay, only) HAM transceiver; and I'm trying to avoid wasting a ton of space in my vehicle (not to mention money) for a proper scanner, or for a CB¹, to achieve fuller coverage of the…
ELLIOTTCABLE
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