Questions tagged [propagation]

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

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Extracting radio signal strength from multiband TIFF file

I have N number of TIFF files corresponding to each radio stations in my data, and I am trying to measure the approximate signal strengths from each of these stations at K geographic locations(say for ...
Parijat Maitra's user avatar
0 votes
3 answers
118 views

How to predict radio range of a product?

I'm shopping around for a next level radio since all I have at the moment is my Baofeng. I've been asking around on my repeater club on how to best choose a radio. The metric I'm most concerned about ...
john_ham_radio's user avatar
2 votes
2 answers
95 views

communicating with France from Oregon

Newbie ham here. My stepdaughter in France is interested in off-grid communication with us in Oregon, and so I am looking into what that would take. If I knew what frequency bands would be best I ...
niels nielsen's user avatar
0 votes
1 answer
109 views

Where can I go for ham radio reviews? [closed]

I was wondering what would be the best startup HF transceiver for the 3-30 MHz band. I have not found any which appear to match my requirements for under $200. What would some ham radio sites be with ...
P.R.'s user avatar
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1 answer
106 views

Centre pole construction for 20 metre half wave dipole

I am about to embark on the construction of an inverted V half wave dipole. It will possibly be multi-band but, for the moment, I want to build it for 20M. Because of the shape of my property, I would ...
jonel's user avatar
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1 answer
81 views

Does iron in concrete streets attenuate ground wave?

My station: microBitx putting out about 8W max into an inverted-vee with the apex around 20ft above the ground. Surrounded by trees. His station: iCOM (one of the older classic rigs dating back to the ...
VU2NHW's user avatar
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3 votes
1 answer
92 views

What steps to take to secure for G2 geomagnetic storm?

So I see NASA has issued a geomagnetic storm watch for a possible G2-level storm on the 11th. I’m at about 53 degrees north geomagnetic latitude. Is this something I need to care about equipment-wise? ...
QuantumMechanic's user avatar
1 vote
3 answers
335 views

What's the realistic SSB reception range for 25W on 20m and 40m?

Because of my living situation I am using a Par EndFedz Mk II Trail Friendly antenna with my IC-7300, since it can do 40m and 20m and is only 41 feet long. However, it can only handle 25W. Now, for ...
QuantumMechanic's user avatar
1 vote
1 answer
97 views

How much is the greatest distance of a communication link that man can reach? Intergalactic? (ascertainable)

I have no data to add, just to say that I would like an answer that includes data and calculations to verify Shannon's law in that case. Concrete examples of this type of communication: http://en....
Mauricio Pagano's user avatar
5 votes
1 answer
60 views

Looking for a model or description of an EME channel

I am looking for any technical/scientifical/specialized reference describing in some detail the moonbounce for VHF/low UHF frequencies. More precisely, I would be interested in a paper or publication ...
user3141592's user avatar
3 votes
2 answers
187 views

Understanding low MUF in VOACAP

I've started playing with VOACAP to better plan and predict conditions on 27 MHz (CB). To my utter astonishment, VOACAP says that I won't be able to communicate on that frequency, regardless of ...
Alexander's user avatar
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2 answers
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Why am I receiving a local tv channel on a CMB frequency

I am using a simple Baofeng H6 dual band radio and I programmed weather channels. Well, on frequency 161.77500 I am actually picking up WGN, a local tv network. This frequency should be reserved to ...
fiacobelli's user avatar
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1 answer
101 views

why does time of day affect propagation when talking to the other side of the earth?

i have been told time of day matters for hf propagation. for example, 80m works best at night. but if i qso with someone on the other side of the world, it's daytime. do they just need more power? can ...
SRoberts's user avatar
1 vote
2 answers
656 views

Sanity check: Should I be able to hear this 20m beacon?

I’m in Sacramento and have an EFHW antenna about 30’ up. I expected to be able to hear the W6WX 14.100 beacon without issue but I cannot. The distance is about 140 miles and the beacon transmits its ...
nall's user avatar
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3 answers
177 views

Radio Waves propagation (Intuitive Understanding of Wave propagation)

I have few similar questions regarding Radio waves communication particularly FM and AM type of Radio wave communication. Please bear with the naivety of the questions. Questions: Radio waves in FM ...
Newbie's user avatar
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177 views

How Does the Propagation of H-pol E-M Fields Compare to That of V-pol E-M Fields (other things equal)?

A rather popular belief on this topic is that h-pol is superior to v-pol. Probably that is traceable to published "far-field" patterns over a lossy ground plane generated by Method of ...
Richard Fry's user avatar
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Why does the HamQSL website say the 40m band is fair and the 20m band is poor during the day?

http://www.hamqsl.com/solar.html Why is 40m shown as "fair" while 20m is "poor" during the day. Shouldn't 7 MHz be getting absorbed by the D-layer more than 14 MHz?
Macuser's user avatar
  • 178
10 votes
5 answers
2k views

Non-traceable radio emitters

There are various techniques for locating a radio emitter. But what are some methods to make this really difficult? There is usually a patch to every vulnerability, at least from the world where I ...
Chi non salta Pavarotti è's user avatar
-1 votes
1 answer
641 views

Transmit data over HF signal 10,000km away [closed]

I would like to transmit trinary data (-1,0,+1) on 20-30m wave to be received 10,000km away. From Europe to US. My first thought was this: https://www.researchgate.net/figure/Burst-modulation-mode-f-...
Boppity Bop's user avatar
2 votes
3 answers
863 views

Long range HF polarization

Is it possible to polarize HF signal (20-30m) at long range (thousands of km)? It was commented in my over questions that polarization is not feasible at long range. However in this article is ...
Boppity Bop's user avatar
1 vote
2 answers
229 views

Hexbeam receiving in other directions

Have a K4KIO Hexbeam up at around 20-feet on the corner of a flat metal roof pointing at 290-degrees bearing (Europe, from Sydney Australia). Currently the Hexbeam is fixed to that direction as i don'...
t252's user avatar
  • 697
0 votes
4 answers
335 views

Send on-off radio signal 5,000km

I remember long range radio stations which still worked 30yrs ago. I could listen to the whole Europe. I also think I saw movies where radio enthusiasts could talk all over the world.. I never looked ...
Boppity Bop's user avatar
4 votes
3 answers
87 views

What kind of antenna for an automatic high bands monitoring station?

I would like to monitor NCDXF beacons, and WSPR. What kind of antenna would be good for reception in the bands of 6, 10, 12, 15, 17 and 20M? Some antennas I considered: A trapped dipole, with traps ...
hjf's user avatar
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4 votes
2 answers
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What is the best time of day to contact Japan from the east coast?

What are the best times in early April to contact Japan on 40M and 20M from Pennsylvania?
Sig's user avatar
  • 41
1 vote
2 answers
1k views

Loop on ground for transmit?

If a large horizontal loop antenna, insulated but laying at ground level, works as an MF and low HF receive antenna, why (even though it has very high ground losses) can't it be used for transmit (to ...
hotpaw2's user avatar
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3 votes
2 answers
796 views

What is the radiation pattern of an ~60 foot end fed wire antenna used for 40 meters?

I live in a retirement center. The rule here is “Never do anything anywhere at anytime.” That translates to “No Antennas” which I have been told means I can put out an antenna as long as it is ...
Bill's user avatar
  • 31
5 votes
1 answer
198 views

Looking for a book that contained a circuit for receiving (literally) underground amateur radio transmissions

In this comment in Earth Science SE I've said: This is a really cool question! I remember (a long time ago) reading about electromagnetic waves inside conductive soil that travelled near but below ...
uhoh's user avatar
  • 543
7 votes
3 answers
3k views

How to determine frequency and launch angle given a target skip distance?

I would like to communicate with someone 1000 miles (1600 km) away. I'm not sure how to target a specific distance. (image source) I assume it's an interrelation of the following factors: Which ...
bitsmack's user avatar
  • 181
5 votes
2 answers
796 views

What gain and power are required for successful DX contacts on 2m/70cm bands in CW?

I would like to practice in CW on 2m/70cm bands when and if there will be a tropospheric or sporadic-E propagation. However I don't have mush space for the antenna. There is a possibility to install 3+...
Aleksander Alekseev - R2AUK's user avatar
1 vote
0 answers
109 views

HF propagation prediction using machine learning

Anyone out there know of or developed s/w to predict HF conditions using ML?
KG6ZIC's user avatar
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6 votes
1 answer
239 views

Using shortwave communication, how difficult is it to transmit messages from the UK to the US?

Is it possible to transmit a short message via shortwave from the UK to the US, across the Atlantic ocean? From what I understand, long-distance shortwave communication has lower bandwidth ...
p.luck's user avatar
  • 163
0 votes
1 answer
321 views

If i transmit on the same frequency using two separate transmitters joined together will they both add up in a reciever to produce a stronger signal? [duplicate]

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 ...
Andrew's user avatar
  • 3,655
4 votes
2 answers
660 views

What causes the light and dark bands (of background noise) in an HF waterfall display?

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 ...
Josh's user avatar
  • 138
3 votes
2 answers
183 views

What is really happening during RF ionospheric refraction?

We all know that the ionosphere — when charged — refracts RF energy, but why? In other words, what is actually occurring at a molecular level to cause radio waves to bend back to earth because of ...
Dave G's user avatar
  • 295
11 votes
6 answers
339 views

Practical limits to maintaining coherence in an HF channel

Lately I've been thinking about weak signal communication on HF. Very weak, like weaker than even WSPR could achieve. It would be nice if one could simply take any existing modulation and slow it ...
Phil Frost - W8II's user avatar
0 votes
1 answer
162 views

Vertical Antennas

I have just changed from a ground mounted Vertical antenna , to a MFJ-1796 Vertical antenna, due to not having big enough ground to bury as many verticals as recommended. So far what I have found is ...
N3JPL's user avatar
  • 3
2 votes
1 answer
161 views

Propagation Analysis with WSPR / RBN

I would like to analyze data from the Weak Signal Propagation Reporter (WSPR) and/or the Reverse Beacon Network to understand the propagation mode(s) of the recent welcome spate of CW and SSB contacts ...
Brian K1LI's user avatar
  • 7,808
2 votes
2 answers
2k views

What is this burst transmission sequence across the entire band?

Fairly regularly on the 40m band I hear a quick blip of a tone, and when I look at the waterfall I see these brief transmissions all across the band that look like little dots. What is causing that?
SandPiper's user avatar
  • 777
6 votes
2 answers
158 views

Propagation effects of noctilucent clouds

I know auroras are a propagation mode, but I was wondering with the recent outburst of noctilucent clouds (as reported on www.space.com) brings with it any interesting propagation modes, either on HF ...
Duston's user avatar
  • 929
2 votes
2 answers
180 views

Restricted line-of-sight communication

Why do line of sight communication links have a restricted range for a given tower height? Is it only because of the Earth's Curvature?
Muhammad Ahmad's user avatar
5 votes
5 answers
2k views

Loop antenna layout and radiation?

I've got, for the near term, limited resources to put up an HF antenna at my home. One of the options I can manage without excessive cost is a loop, which would enclose the house. I need to transmit ...
Zeiss Ikon's user avatar
  • 4,087
3 votes
3 answers
142 views

Given the classical top down view, what does a bottom up view of RF waves look like?

Quote from Wikipedia, Photons: "Nevertheless, all semiclassical theories were refuted definitively in the 1970s and 1980s by photon-correlation experiments. Hence, Einstein's hypothesis that ...
Cecil - W5DXP's user avatar
4 votes
3 answers
2k views

Line of sight from geographic/map data?

I have line of sight issues with repeaters I want/need to use (it's a repeater network my club uses). One of the options that might be available to me is to install a "passive repeater" in a location ...
Zeiss Ikon's user avatar
  • 4,087
3 votes
2 answers
308 views

Is there a trick for reaching a repeater "through" terrain?

I live in a draw, well below local average ground level. There are two repeaters I want to be able to use (because they're in the network my club uses). One is in the 440 band, thirty miles away but ...
Zeiss Ikon's user avatar
  • 4,087
5 votes
4 answers
9k views

How can I be sure I'm actually hitting the repeater?

I'm just starting to use 2m and 70cm bands, which normally use repeaters to extend range beyond a mile or two (limited mostly by line of sight, as I understand it). When I'm at home, however, I'm not ...
Zeiss Ikon's user avatar
  • 4,087
4 votes
1 answer
127 views

High-resolution GIS datasets of groundwave conductivity of the United States, besides the FCC?

The FCC publishes a map of estimated groundwave conductivity of the United States, but the resolution is quite low: Are there any GIS datasets that include groundwave conductivity at a higher ...
Michael A's user avatar
  • 185
3 votes
1 answer
2k views

Where does the year 2019 fall in the sunspot cycle for HF propagation?

I am reposting this question about the year 2016 here. This is 2019. Are we now at the good or bad portion of the 11 years cycle? What effect are we seeing now? How large (strong/deep) is the effect ...
Mike Waters's user avatar
  • 7,843
10 votes
4 answers
1k views

Better explanation for beyond-line-of-sight VHF signal reach than "lower curvature to radio waves"

I am currently studying for the Technician Exam and have come across an answer to a question I think is ridiculous. The question is: Why do VHF/UHF signals usually travel somewhat farther than ...
Dave G's user avatar
  • 295
6 votes
4 answers
9k views

How far do radio waves travel?

I have read that radio waves just keep traveling but the signal gets weaker because of how the wave spreads. OK, I get this, but what confuses me is that satellites emit signals from space that our ...
sirshakir's user avatar
5 votes
1 answer
1k views

Why are the lower HF frequencies not working during winter day time?

Currently my location is Nepal. We use the ICOM f-7000 radios without the antenna tuner. We use the frequencies round about 5-9 MHz, for communication over distances between 150 and 400 km. During ...
Angry Hooman's user avatar