* Ground Wave Propagation *

Off Topic Lounge
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***1/2 wave antenna 17 ½ feet***

A vertical 1/2-wave antenna is highly effective for local 11-meter (27 MHz) CB ground wave propagation, providing reliable local communication within a typical range to 70 miles. Typical in city 20 to 30 miles

Earth’s contour without requiring a massive radial ground plane network. With only a 15 to 25 foot Antenna

⁜⁜⁜⁜⁜⁜ 102 inch antenna ⁜⁜⁜⁜⁜⁜

a 1/4 wave vertical antenna relies heavily on ground wave propagation for its local communications. Ground waves track the curvature of the Earth, providing steady, reliable, line-of-sight and near-horizon coverage up to roughly 30 to 50 miles, depending on terrain, In city it will drop below 10 miles

⁜⁜⁜⁜⁜⁜⁜⁜ 48 inch Antenna ⁜⁜⁜⁜⁜⁜⁜⁜

Urban/Obstructed Terrain: 1 to 3 miles. Buildings and terrain severely dampen the already weakened ground wave.

Suburban/Open Roads: 3 to 7 miles. Typical vehicle-to-vehicle range under normal operating conditions.

Flat Rural/Waterways: 7 to 15 miles. Saltwater or highly conductive, marshy flat soil dramatically improves ground wave

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David, I know you like to make a few wild claims, but a reliable local range of 70 miles? Frankly, I’m amazed you are convinced on that one! 4 Watts on one of those, back in the CB heyday in the 70’s that would have been utter chaos when there would have been thousands of people in a huge area like that?

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Using a Monopole Antenna ½ wave t 102 inch you can get over 100 miles. Yagi to 102 inch is 160 miles that saw in 1962 . I have had reports of 200. Miles.

In city with all the buildings the range with a Monopole Antenna to 102 inch drops to a reliable of over 20 miles maybe 30 miles.

I have had 4x4 reports almost 200 miles from one side for valley to other side using a 102 inch

If use under 48 inch the range drops to few miles unless to to base station.

If you use the new 18 to 24 inch to 18 to 24 inch you down to just a 1½ to 3 miles

In Citizens Band Radio :radio: it is all in the antenna you use

Dave

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Dave. If the forum hosts had a customer ask what the range would be on that antenna they would never in a million years say 100 miles. In fact they’d have their fingers crossed and hope nobody recorded them even saying 20 miles. Look at the claims made by sellers on Amazon on some radios that have similar power. Amazingly ambitious and with HF you can really only claim ground wave with no help from the atmosphere and range is just topography. I live in England and in the east where we are flat. The notion of getting more than 30 or 40 miles is frankly something that is just going to happen. Even two of those antennas, one each end would never be reliable. Sure, one day when things are favourable it might work, but in half an hour it’s gone again. Radio links just do not work with stated distances. There are some on line calculators where you enter frequency, antenna gain and power and 4W is never going to predict 100 miles and even illegal powers don’t increase range predictably over a nominal amount. I just tried a couple and they predict 5 to 10 miles!

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I would look at your antenna and the other person antenna.

I can easily get on my ½ wave monopole get over 20 miles in city. The milage was by cross streets over 20 miles .

When I had pickup is under 4 miles withe antenna that fit the garage lessthan 45 inch. Bit new that was a problem too.

Here one this on range is weather satalites use a 5 watt radio and typically 25,000 miles.

On a skip I have received over 4,500 miles in 1980’s.

This year skip is California to New Jersey 2,450 miles.

Where live on a everyday usage it over 20 miles to mobile radio

I have a lot reports on base station to base station over 50 miles on a everyday usage.

Where live because I am in valley about 110miles before skipping I just need to find someone and see we can contact each other.

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The biggest problem I have is getting a person apx Location. I may have had a lot great distances but everyone is afraid :fearful:.

I have had a lot Truck drivers /owners reporte using there twin 102-inch a range over 30 miles driving in the Midwest. I Valley I live there report is over 25 miles driving highway 5 and 99. In city they are happy if get 10 miles most time it was 5 miles. This just change of location.

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Well maybe you live in a magic Kingdom David because physics just doesn’t work like that without assistance from the ionosphere or topography.

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It just reported data or what I saw for myself.

It’s the ground wave propagation.

So what size antenna do you use on 11-meter :red_question_mark:

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If you using a Rubber Ducky antenna this is -20 db

This will give you a very poor range.

You need for a good ground wave propagation range at less 1 db or higher on 4 watts 11-meter.

That probably your range problem. There are other things that could problem but biggest

Dave

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Here a chart on distance for ground wave propagation on 27mhz.

I do agree with numbers for everyday usage in city.

The numbers are better beyond the city in farm land and lack of building not given in chart.

It is not AI I just check on what others said subject and did want Change their wording.

It did not show small antenna like the rubber duck or 24 inch the mobile likes like a 60 inch

Ground wave Propagation needs a less 48 inch and best Tobe over ¼ wave size . Most figures on base stations are ½ wave.

I hope this helps on range

Dave

Key Range Breakdown

  • Mobile-to-Mobile: 3 to 7 miles. Limited by low antenna height, vehicle grounding, and legal 4-watt power limits.

  • Mobile-to-Base: 10 to 20 miles. Benefiting from the base station’s superior antenna height and gain.

  • Base-to-Base: 20 to 70 miles. Achieved when both stations utilize high, clear vertical antennas and clean terrain

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If wonder why the difference in range I will take base station to base station.

In Arizona where dry and sandy ground wave propagation is very poor and the grounding is very bad. Very close to line-of-sight. Line of sight is 15 miles and ground wave propagation is about 6 miles and worst on bad day

Now in Midwest with irrigation and a clay sand soil Ground wave Propagation does very a easy 70 mils on clear day . Still Line of sight is 15 miles but ground wave propagation is 24 miles for total of 39 miles. Ground Wave Propagation can be over 48 miles or total 68 miles . Remember conditions have to right for this distance

Over ocean can be over 120 miles

In city you may not get a lot from ground wave propagation may be 2½ miles line of sight 15 in total of 17½ miles You see this in city like LA . Most city it is 16 miles plus line of sight of 15 miles or 29 miles.

Bad weather like :umbrella_with_rain_drops: rain, fog :fog: or :cloud_with_snow: snow will reduce ground wave propagation distance by upto 60%

Lots to think about I. Ground wave Propagation

  • Base-to-Base: 20 to 70 miles. Achieved when both stations utilize high, clear vertical antennas and clean terrain

Dave

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David. You keep changing the goal posts. We have gone from claiming 100 miles to now 20 miles. We have suddenly introduced base antennas at both ends. What seems to be happening is you Google something, with I suspect AI results and assume it’s correct. However, your posts always lack any context. Ground wave, for example, in your posts relates to HF that is not being reflected from the various levels of the atmosphere, as so called ‘sky wave’ propagation. You seem to have not taken so much into consideration and are tying yourself up in knots. Remember that ground wave propagation runs out of steam as frequency rises, and is usually considered gone by 30MHz. So at 27MHz, it is hardly different from line of sight. The ground hugging phenomenon that increases distance for the lower frequencies is almost gone, and the type of ground is pretty important. This is why you are repeating all the claims. 20 to 70 miles is a meaningless claim. Is it 20, every day, reliably, or is it 70, on the occasional day, in a certain direction. As help to people it actually hinders. When I was a teacher, with some very clever 18-20 year olds I soon learned that answering a question with an answer that was airy fairy was a disaster, educationally. If you answer with a definitive and possibly qualify it, it is accepted. So, ground wave on 27MHz might get you 20 miles reliably, occasionally some paths could be as much as 70. That is a good and correct answer. When you post data. Make sure you qualify it properly, or people will be confused. You then muddy the waters with a random comment about a rubber duck antenna. Antenna have published gain figures. Height above ground matters. Feeder loss is important as is power output. All these qualifiers change your range statements. You seem to pick out some data, ignore other data and present it as fact. No reputable manufacturer includes distance in advertising without lots of qualifiers. In reality perhaps we should say 50 miles, on a good day, with decent weather, going downhill with a strong wind. That is clearly total rubbish, but it serves to make the 50 mile claim more realistically maybe 10 miles? Us old fuddy duddies understand how dangerous claims can be. After all, AI reads your comments and assumes they are correct and learns the wrong answers, but then promotes it as fact. My guess is some of the online answers are just bad answers AI reads all over the place.

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There are a lot different claims in the internet.

If calculate out 11-meter you can get use a ½ wave antenna to ½ wave antenna depending conditions you can get 30 to 130 miles.

Now one claim is 70 miles . Now if city it can drop to 30 miles. In heavy rain it will drop.

Today live city just under 30 miles on a dry day.

When live boonies about 60 to 70 miles

I Have witnesses in 1962 a range of over 160 mile using a 5 element Yagi and 102 wip

To many variables to have a set range. Like rubber duck to rubber maybe 1½mile great construction site give privacy

Dave

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I agree. Too many variables, so the only reliable answer that is of any use is 30 miles. Even that assumes the usual line of sight guidelines. It is the high claims that generate all kinds of problems. Newcomers will see a claim and assume it is correct. even worse, AI reads the same response and if there are enough similar ones, it learns the wrong answer and then promotes it. There are some facts - Ground wave clearly exists. Broadcast stations have used it since inception to let people hear news and music over large ranges. However - here in Europe, back in the 70s and 80s, the BBC on 247 metres was, thanks to groundwave, a UK station - until the evening when radios stations from europe and further afield would suddenly arrive. Indeed, in Albania, Radio Tirana jammed the BBC every evening with constant trumpet music. Come daybreak, it would vanish. CB, the area you are interested in sits right at the upper limit of groundwave propogation, and is on the cusp of groundwave dying - which it often does. No groundwave, and no skywave reflections, and of course no sunspot cycle assistance, unless it’s the once in 11 year thing. What is the point of stating ranges that make no sense? I live in a town that is in the flattest part of the UK, there is a hill about 4 miles north, only a few hundred feet high - only cyclists notice. The next town is 8 miles away. There is NO reliable communications from town to town, without raising an antenna, clear of obstacles, at both ends. Some CB, ham and taxi communication is possible, but there are dead spots. However from here to the nearest city is 30 miles and that path works pretty well. That means when somebody asks me "can I talk to Jim, they live in (next town), the ONLY answer is “possibly”. There is NO magic number. It depends on variables I do not have.

In 1962 of course somebody managed 160 miles - but equally, UK CB people have spoken to US CB people on occasions over the same time period. What we do not know is how? If you hear a dog bark, you don’t know it’s actually a dog? It sounded like one, so probably is. That is what you are describing. There would be no point in radio contests if every weekend was the same.

There is no accurate way to calculate a path at a given time without knowing the precise location of both ends. Then, path loss can be calculated with antenna height, power, receiver sensitivity, and accurate topography maps. This can be ammended to include ground wave propagation but my software is not sophisticated enough to do that in any meaningful way, as it needs more information that I have access to regarding the current state of the environment.

I realise you want to advise people, but the only advice on the subject of range MUST have all the caveats listed, making it useless. Essentially, the correct answer could be 32 miles, unless it’s not.

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I agree

It is good number for City and a ½ wave Monopole antenna to 102-inch (30 miles)

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But under right conditions easily 160 miles using a Yagi to a 102-inch. But most that has this equipment , are License HAM operators and the better off using 12-meter or lower.

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I have read two operators both using monopole ½ or ⅝ wave Antennas a 50 mile range. I have not found anyone with a ½ wave antenna to confirm statement

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Still in most cities base station to vehicle is 20 to 30 miles. So I agree with 30 miles

{ About ½ line of sight and ½ ground wave propagation }

Dave

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I forgot to respond to AI

I have found a lot errors in AI . Most data comes from past when had good information. I will post some times from internet information if compares to past and or calculated data.

I found range internet writes will post a part of real information basically if fits there needs.

The range of 11-meter is wild. VHF & UHF will post 11-meter to match the short range of VHF and UHF (line of sight only) . Today Manufacturers are trying to promote a antenna that is easy to make and fits in a small box. A lot are 18 to 24 inches longer even rubber Ducky :duck: for cars. Looks good in ad photo :camera_with_flash: only.

All this information is feed into AI.

AI does not read ARRL with real data

Dave

PS: For some searches I have us 10 and 12 meter as data on 11-meter is filled full incorrect data base others needs

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The trouble is, a Yagi is a crazily large antenna especially if you need to mount it vertically - because the support pole on top of the rotator has to be at least 3m to get the elements clear of whatever holds up the antenna or the radiation pattern is wrecked. They are better horizontal, but if the station the other end is vertically polarised then the yagi has to be too. even worse, the claims for these are ridiculous too. A 4 element Yagi is quoted in one ad at 14dB gain (not even dBi, or dBd - just 14!) AI reports typically 10dBd gain for a 4 element. Reputable manufacturers tend to be less than 8dBd. David - when you stick one on your house, you’ll be able to state a range. Until then, you are in the hands of idiots and AI. One site claims a 28 time gain increase. That is just madness. A dealer I trust in the UK lists the ½ wave CB antennas as having NO gain, compared to a dipole, which is exactly what they should be. Similar product on Amazon claims. 4.1dB!!!

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The monopole antenna the db depends on ground

On ½wave under 0.8 to 5.15 db

Where the dipole an J-Pole are about 2.15 db They do not need a ground. The dipole was first real antenna design by Henry Herzt later Marcony design the monopole antenna.

If look at a dipole it is two monopole antenna one used for ground. If live in desert :desert: like Arizona you use a dipole or J-Pole. If you steel ship in salt water monopole works the best.

Dave

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David - this again is just not correct. ½ wave antennas, work as 2 quarter wave ones, working together. They do not require a ground plane for their performance. The only real snag is the length - and the need for a matching network at the feed point because it is naturally much higher impedance than a ¼ wave - so usually a coil and capacitor are required to bring it down to 50 Ohm.

Like a ¼ wave and a ½ wave dipole they have ZERO gain. They are often quoted as having 2.15dB gain over an isotropic source - a point source that is purely theoretical - they don’t exist. 2.15dBi and 0dBd are exactly the same. ½ wave antennas have 0dBd gain.

The differences in the designs you mention are due to the vertical angle of propogation. As in where the effective power goes. For a vertical, little goes up, and most goes forward, but the actual angle of ‘maximum launch’ changes. So if you want ground coverage you can choose one design, but if you want the best opportunity for sending it up at an angle, you might pick a different one. Decibels work in strange mathematical ways, but you ALWAYS have to reference them to something else - think of them as a ratio. Manufacturers who use the isotropic source scale look better than another who uses the dipole as a reference. It’s the same argument as comparing a ¼ wave groundplane, or a dipole to a J-Pole or a Slim Jim. The only place more oomph comes from is by changing where the antenna directs it. Antennas just distribute your available power in certain directions.

How about these two explanations Google found for me.

A half-wave (1/2-wave) dipole antenna has a standard gain of 2.15 dBi (decibels over an isotropic radiator) or about 0 dBd (decibels over a reference dipole). [1, 2, 3]

So - confirmation that there is no gain difference between the ½ wave and the dipole.

However - Google also says:

1/2-wave antenna provides roughly 1 dB to 2.1 dB of improvement over a basic 1/4-wave whip

This appears to contradict the other claim - but what it is really saying is that the radiation pattern - that is for the ¼ wave a typical doughnut shaped plot - gets squashed down, making it less sensitive /efficient upwards and a bit better closer to horizontal.

Don’t get excited because 2dB change is hardly noticeable. It’s there, but it’s not a lot.The other upshot of the squash is that they are less good for skip conditions, as the aims is more ground distance. Just remember to check if specs are in dBi or dBd when you need to compare, and unless the specs also detail the vertical radiation pattern, you are just hoping and guessing.

There are lies, big lies and Decibel figures!

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That true about lies

It trying work the truth.

My data comes for old and new data on ½ wave 27mhz.

The dipole and J-Pole have 2.15 the monopole is a wide from 0 to 5.5 db the figures go back to ww2.

I would if they use figures from ww2 for today’s advertising. They same even if I use AI there everyone copies the other. What is odd is no realible data on using a UFER ground.

FYI the UFER was designed for radio and bomb storage in ww2

Good luck on finding better data.