Questions tagged [propagation]

Questions about RF propagation including measurements, beacons, modes (ionospheric, tropospheric, ground wave), etc.

Filter by
Sorted by
Tagged with
2
votes
2answers
1k views

High data rate on HF & MF bands

Is it possible to transfer data at a high rate, like 1-2 Mbps, on 0.5 - 30 MHz? From Shannon's Theorem, with a bandwidth of just 300 kHz it is possible to reach 1.5 Mbps. I want to use these bands ...
1
vote
1answer
605 views

In which direction should single wire antenna in underground parking be pointed?

In our collective building lot we have an underground parking, in which a company recently changed a functional garage door system, since then the reception is a lot worse than before. (Like it doesn'...
4
votes
5answers
1k views

How does one know when band conditions are optimal and what factors to consider?

On many of the DX sites, one will find many variables for solar weather to include flux, A, K, sunspots, etc… I’d like to know how to read those and know what to look for. As I understand it, the sun’...
10
votes
4answers
6k views

How do I find out what bands are open?

Say the deck is stacked. I'm out in the country with an all-band QRP home-brew rig, and an active antenna. Or say ship-wrecked and marooned on that desert island. The battery only has enough juice ...
2
votes
1answer
318 views

Find RF transmission distance

I guess my question is as follows: if I find FSPL (there will be no buildings or anything blocking/diffracting), can I figure out how far the signal can be transmitted if the receiver gain, loss and ...
-3
votes
2answers
190 views

Visible radio wave propagation [closed]

Has anyone actually seen a visible radio wave? If so please comment. I am just wondering if it has ever been recorded before. or if its something that was left out of NEETS or is maybe top secret.
15
votes
2answers
23k views

How do I make a RF propagation map for a repeater?

Let's say I have a repeater. Knowing all of the information about antenna height and gain in each direction, as well as power, how can I create a map similar to this map I saw of a repeater in ...
4
votes
1answer
319 views

2 m meteor scatter FM voice freq?

What frequency should I use to try and make meteor scatter contacts on 2m FM tonight, with a nice meteor storm coming?
28
votes
2answers
74k views

Which HF bands are best during the day and which are better at night?

I am rather new to HF operation and have recently purchased my first HF rig. I have read about bands being "open" and "closed" based on various conditions including time of day. As I have been ...
8
votes
3answers
7k views

Why is the electric field orthogonal to the magnetic field from an antenna?

I've read in several places that the electric field is 90 degrees orthogonal to the magnetic field, and both are orthogonal to the direction of the wave from a transmitting antenna. What causes this? ...
4
votes
1answer
414 views

AM vs SSB weak signal

I know single sideband is much better than FM for weak signal receiving. I know that SSB is just like AM, but with the unneeded parts removed. For weak signal propagation, like EME and aurora, would ...
6
votes
1answer
606 views

Can tropospheric scatter effect be used by 802.11 links?

What are the lowest EIRP and antenna gain requirements that make possible use of troposcatter at the distances of 100 to 150 kilometers assuming conventional WiFi (6 Mbit/s data rate with OFDM/BPSK ...
8
votes
5answers
18k views

How far can a 2.4 GHz, 1 watt signal go in a rural area?

What's the approximate range achievable by a 2.4 GHz signal of 1 watt in semi-urban areas? I can see 2 km from our rooftop. Will a 2.4 GHz signal go that far, i.e. if I send WiFi signals from our ...
3
votes
2answers
424 views

How can I know over what distance or at what speed I can communicate? [closed]

Given some description of some parameters like: transmitter power frequency antenna location time of day how can I know over what distance communication is possible? Can I know the limits to these ...
1
vote
2answers
232 views

How is the 10 m band performing now in January 2014? [closed]

I bought a 10m radio on eBay back in 2007 during the solar minimum when 10m propagation was nothing to write home about. I verified that the radio worked at that time, though it didn't seem to work ...
5
votes
2answers
2k views

Best QRP HF band for small antenna?

What HF bands, times of day and/or conditions might be best for attempting to make non-local contacts using QRP transmitter power (around 1 Watt) and a small indoor folded or loop antenna?
9
votes
1answer
960 views

What are the general effects of a geomagnetic storm on propagation?

Per NOAA/NWS Space Weather Prediction Center, "SWPC Forecasters are anticipating G3 (Strong) Geomagnetic Storm conditions to occur January 9 and 10." What does that mean, very generally, for amateur ...
2
votes
2answers
89 views

Does propagation affect magnetic and electric fields equally?

In the HF bands loop antennas are common, which, if I understand correctly, emit most of their radio energy into the magnetic field, whereas most dipoles emit largely into the electric field. To take ...
3
votes
1answer
65 views

What are some reliable sources of propagation forecasts?

Where can I go to find propagation forecasts? How useful are propagation forecasts over time? For instance, I've been told by meteorologists that weather forecasts three days out generally ...
5
votes
1answer
218 views

How to obtain raw data for Global Real Time foF2 Map

Note!!!!: I am not looking for help with how make a map using Google Maps API (that part is done). I need help with finding data. I am building a shortwave radio/HF listening log book online, and it ...
9
votes
1answer
133 views

Around the world propagation?

Is it possible to transmit a signal around the world and receive it? Has anyone done it, and how? If not, how could this be accomplished? Assuming a complete path around the world, what kind of time ...
10
votes
3answers
486 views

Using MIMO in Amateur Radio?

MIMO, Multiple Input, Multiple Output, is used widely in commercial data transmission. 802.11n and LTE devices use it to increase throughput, link reliability, and channel usage without increasing ...
10
votes
3answers
428 views

Does modulation affect propagation?

Does the modulation scheme, whether OOK, SSB, AM, FM, a digital mode, etc, affect the propagation of a signal?
8
votes
2answers
546 views

How do sunspot numbers (SSN) affect radio operations?

I frequently hear talk about SSNs in Amateur Radio, and somehow if the number is high, that's a good thing. I just don't really understand what they are, and what they mean, and I'd like to better ...
6
votes
1answer
11k views

How to determine antenna height for given HF frequency and coverage radius?

I'm planning on setting up a low-HF antenna for near to mid-range contacts. In my particular case, ideally I would like to be able to cover a radius of approximately 1000-1200 km with good ...
6
votes
1answer
313 views

1280 MHz propagation out of a mountain valley

I live in a small valley, surrounded on three sides by 200-300 foot ridges. I'm trying to figure out where to place an antenna mast to receive 1280 MHz video from a long range aerial vehicle (20-...
9
votes
2answers
360 views

How does the South Atlantic Anomaly affect propagation in the HF bands?

At ~34ppt the Southern Ocean is significantly less saline than other major water bodies (Arctic Ocean excluded). The Southern Continent also shares proximity to the South Atlantic Anomaly - where the ...
16
votes
4answers
27k views

What bands and modes will give me voice at 3,000 miles?

I pursued Amateur Radio primarily for local emergency communications and as part of my electronics education. My only radio right now is an inexpensive 2m/70cm HT which is good for local weather ...
9
votes
1answer
902 views

What is the correct procedure to beam long-path?

I'm new to directional beam antennas, and saw that K9W Wake Island DXpedition was working 10 meters "long-path" at 1230z, or 6:30a.m. in Texas. This was late enough for the sun to be coming up, but is ...
10
votes
2answers
5k views

How much RF energy do trees and branches absorb?

For the 20m - 10m and 6m bands, will having my dipoles below the tops of trees (I live in redwood forests) drastically affect the RF power out or radiation patterns of my dipoles if I can still get ...
11
votes
6answers
3k views

Does iron ore in the ground affect my signal?

Mineral content in the ground varies from one place to another. I've visited places where the ground & waters were an orange-red shade from the high iron content; not good for trees either. This ...
11
votes
2answers
372 views

What would propagation look like on Mars?

If we could get a few HF stations on Mars, what would the propagation look like? Thought shamelessly copied from this blog.
8
votes
3answers
1k views

What is the proper way to ground your station's antenna?

I don't understand how you would go about giving an RF ground to your antenna. Would it not become an additional radial and affect the signal? What is the proper way to ground your station's antenna?...
14
votes
3answers
617 views

Why do concurrent FM signals not mix together?

Generally when I hear two conflicting signals they do not mix together, but rather one dominates then the other. This phenomenon can be observed on FM broadcast station when driving out of range from ...
4
votes
3answers
8k views

How and why sunspots affect propagation in HF bands?

How and why do sunspots affect propagation in HF bands?
8
votes
1answer
121 views

Are ionospheric predictions useful in practice for ham radio operators?

A number of government agencies around the world provide ionospheric predictions, such as vertical foF2 or oblique path useable frequency range advice. Examples include IPS, SWPC and DIAS. Typically, ...
10
votes
8answers
6k views

What is the best time of day/Band to make a contact with Hawaii from the East Coast?

I need to get Hawaii for Worked All States, and live on the East Coast (Virginia). Furthermore, I have a poor antenna, and thus only the prime times of the day seem to really be opened for me. What ...

1 2
3