FLAT COILS-VS-ROUND COILS

[Foxhunter]

LOOK: If anyone is interested in reading a good comparison article with real data on two of the more popular "coil" antennas I was attempting to mention above (the Predator and Monkey Made antennas) here is a decent review article here: (it also provides numbers against the 102-whip and Francis 5'5" stick)

CB Radio Antennas, Which one is right for you? CBradiomagazine
http://cbradiomagazine.com/Fe ... %20you.htm

======== there are no signal tests, and no proof in that article. just because an antenna has lower swr, does not mean it is more efficient ,lol. its a selling gimmick. so..if i take a round tube, and pound it flat with a hammer, it has more surface area ? it will have the same surface area... if a coil is any thicker than the vertical radiator, its not adding anything. what makes a coil efficient is the spacing,material and dielectric. everyone will try to tell you different, but know for a fact any antenna with a coil is not as efficient as its full length original size. all coils induce loss. some are so close u almost couldent tell, but will never equal. 209

Well I nearly completed a posting here earlier but a lightning strike killed the power to the house and the PC. Hi 209 I see you meant to quote a previous post of mine and had pointed out the CBRadioMagazine link I provided.


You know, one day I spent about 5 hours searching online for anything that would show any type of data at all on these two types of coiled antennas, particularly the Predator 10K and the Monkey Made antennas because they seem to be the most popular and are also chief competitors.


After all those hours & hours, all I could find were countless commercial websites selling and promoting their products and of course numerous online forums with people also promoting their brand-loyalty. I'd invite anyone here to spend time looking around and find something even remotely worthwhile. The CBRadioMagazine link I had discovered last year and posted a link to for some outside reading on the subject of the two brands. Far from being a "scientific" analysis of the antennas, it did seem to compare the two and be somewhat unbiased. That's all, and still worth a read.


It is commonly said that a "$400 radio with a $25 antenna performs like a $25 radio system". True that--that true.


Flat vs. Round? I don't know in the end I guess. It's a Pandora's Box subject with much speculation. The question is "which is better" I think.


As far as "the shape" and how electric/electromagnetic signals react to conductors? I do know with near certainty that any electrical current travels more efficiently along the skin of a conductor. I do know too that according to the NEC book-----even with a large thick solid wire conductor----current only flows along the surface and not within the solid core.


Given two identical mass metallic conductors, more current (ampacity) will more easily flow on a stranded or tubular surface than with a solid one because of more surface area. What I was saying was that it appears that a tubular surface is more 3-dimensional and has more surface area. Since this is a loading coil with nominal voltages we are all discussing, then I don't know in the end what bearing that would have, perhaps none. Doc had a good point there also, that RF does not like sharp edges as the Monkey Made and other similar flat coil antennas have. "Round" seems to be an ideal shape to electric fields and currents.


If I ever had real time and money (as in "Powerball" or "Mega Millions" ) I would absolutley contribute something back into this age-old argument in the form of actual unbiased laboratory analysis. I'd love to and would put many CB products to a scientific-method comparison, done for consumers much in the way "Consumer Reports" magazine has done with other products on the market. I tell you with absolute certainty I would start with "CB Antennas" and go from there. Comparison, features, performance data----everything. People need ACTUAL/FACTUAL/UNBIASED information not sales pitches. Like Dragnet with-----"just the facts" ma'am.


Did anyone know-------that often the number one reason a woman will buy a car (or choose one car over another) is because of the number and placement of it's cupholders ??? True, Google or Yahoo it.

I wonder how many guys end up doing a somewhat similar thing----with their choice of their CB radio gear or antennas----without even realizing it ??? Hmmm . . .


I admit I do have two Predators and a Monkey Made, but I also have two 1/4-wave whips and about 30 other various mobile antennas. I've had enough success with what I've tried in the past to be generally satisfied, but I think too alot of that had to do with a good mounting location and decent overall installation in general. And wattage.


I think CB Coils---ie "spring fever"---have really taken hold.
He we are at the new antenna assembly factory . . .






It was mentioned about coil base antennas. What comes to mind immediately for me is the Bencher Butternut HF9V. People are using them and claiming good results, but people have claimed alot of things. Still they have a loyal following. I do have a nice chrome Bencher BY-2 Iambic Paddle keyer from them (first one was/is a US Signal Corps J-38)---just have to learn how to use the &^%@ things they're alien. Anyway how about a Bencher "mobile" antenna?


Pssst . . by the way----I see they are using round coils.

How'd that look mounted on a Suburban ??? Have that comp look

[Slowdraw]

I have an HF-2V and although it is a good antenna (worked Guam on 100 watts the other day) it was a pain to tune right. Not an antenna for beginners.

Hams know that no matter what shape the coil is, or what color the coax is.. what matters much more than any of that is the ground system. That is especially true with mobile antenna systems.

Theoretically there is a very minor difference between flat and round coils. Flat coils (theoretically) have less capacitive coupling between turns due to the flat edges facing each other in the coil. It is very, very minor in large coils such as what we are talking about. The shape and proportions and surface resistance are more important by far. Where are the gold plated coils? Someone could make one and people would buy them!

Much more relevant are such things as antenna location, ground path losses, antenna coil coupling to various parts of your car/truck (such as roof or cab) and durability.

As many in this forum have stated before, always use the tallest antenna you can with a coil as high up the shaft as practical. Larger coils have fewer losses, but there is a point of diminishing return. Common sense should rule here.

Personally, I like the Predator antennas because they work well, they are built well and very light weight for their size. I've tried to get Kale to build a 20 meter version for me, but so far, I've had little luck

Slowdraw

[Century21]

i have a gap titan dx. There was no tuning required and it works great, but a long inverted V with no tuner worked better on 75 and 40 meters, but the gap worked better on all other band.

[rumblefish]

you shouldn't see or hear one bit of difference between around coil antenna and a square coil or a flat coil antenna.
In antenna theory the coiled portion of the antenna will have little if any radiation coming from it .

[Fast4socal]

The shape of the wire, like Mopar2ya said has next to nothing to do with angle of radiation and just a very little to do with efficiency.

Flat wound coils "can" have a higher "Q" (think lower loss here) in most cases due to the fact there is less surface area facing each other between windings resulting in lower capacitance between turns. This allows one to use just a little less wire for the same inductance. At the size of the coils that are used on antennas like the Predator, Monkey, etc., the difference would not be noticeable outside a laboratory.

3 things in respect to loaded antennas (anything shorter than a 1/4 wave whip) that do matter.

Coil shape: There is an ideal proportion for highest Q and lowest loss, that is twice as long as it is wide or a 2x1 shape factor. An example would be a coil that is 8" tall by 4" wide. Again, with the larger coils on the higher end antennas, a little deviation is a moot point, it won't matter.

Coil position: The higher the coil is from the base of the shaft, the less current flows through it and therefore will have lower resistance (Q) losses. power= current(squared)*Resistance..... in other words... if you could measure the current through the coil, and square it, and multiply it by the resistance of the coil, you would have the power lost by the coil.

There is also more loss due to your ground system, which is never perfect, if the coil is closer to the base or feed point of the antenna. This is usually the LARGEST LOSS of any mobile antenna system.

Coil surface conductivity: Most people are aware of this one. A shiny gold plated surface would be ideal, but costly. (I'd pay for this, but who makes one?) Copper, next for a few days until it corrodes. Aluminum would be next best. Hams prefer cadmium plated aluminum, but nobody does this for CB'rs? Why not? Never bother with a shiny chrome plated antenna coil. It looks pretty, but chrome makes a great resistor. Remember the Predator (NOT THE PREDATOR 10K) antennas the truckers used to like many years ago. There was a reason the SWR was flat for so many channels.. It made a great dummy load!

This is probably wordy enough that most ppl won't read it all the way through, so I'll end it here. If anyone cares for more info, I'll write some more. There is still a lot of misunderstood information out there about antennas.

Examples: 2.5/1 swr may mean your antenna is great and you have a really good ground plane for your short efficient antenna. There is a way to achieve a perfect match.

A 1/4 wave whip above a perfectly conducting ground plane would have a 1.5 to 1 SWR reading.

The higher Q or lower loss an antenna is, the narrower the operating bandwidth of the antenna will be. (Beware antennas that show flat across 120 channels) Ground losses figure can into this. I had to learn about this and the two items above, the first time I put an Audio King on the roof of my van and the SWR was 3 to 1!

There is an ideal length of coax, but probably not for the reasons you think!

I can go on, but I run the risk of putting ppl to sleep... LOL

when you say Q are you talking about the Q point on a charistic curve?

[76Q]

I'd like to offer another perspective. Practical antenna performance is governed by more variables than can be mitigated in one sitting or discussion. Within the context of what operators are trying to achieve, I think it has already been mentioned, but I'll restate anyways- The antenna that meets your communications objective whether it be best groundwave distance or skp distance desired while being practical in form and longevity is the ideal antenna.
Regarding the type of coil design, it is clear that coil design does affect coil losses on transmit, losses in the form of heat. These losses between one form of coil and another varies between one antenna or another depending on the specific design of coil, and its physical dimensions. Also as already been eluded, the less the coil winds interfere with itself (via inductive coupling of waves travelling around the coil winds) the less inductance and the longer the antenna has to be in order to tune. So, the taller the "tuned" antenna, the less loss, the more efficient, the less inductance required, the less coil winds, etc. But, there are so many other variables that affect TX and RCV. A monstrous antenna generally has more RCV capture area, resulting in better ears. The taller the antenna the more vertical obstacles can be cleared also affecting RCV (there's more to even this when you consider multipath propagation, horizontal clearance, polarization, etc... it goes on and on) On TX the monstrous antenna generally has better power handling, thus less energy is converted to heat due to electrical loading on the antenna. This last point leads to my contribution in this post:

Now the point which no one has mentioned yet in many articles that I've read, probably because it points to a taboo usage situation (even for HAMS) and that is power handling. Simply stated, an antenna that has higher power handling (real power handling, not just claimed) will hold stable as power ramps up, this can tranlate into "audio" performance in AM, and TX/RCV swing in SSB. If you are wondering why this is you may refer to the technical power components of an AM signal. In AM mode, when you key down, carrier power is generated into the antenna...as you speak (modulate) power ramps up (100% + over the carrier energy for those whackpacked users). The ramping of power must be handled by the antenna in order for the radiated wave to represent the intended signal successfully. This is the reason why whimpy antenna structures can have poor perceived audio. To conclude, although the antenna has nothing to do with audio power modulation generation in the radio, it can affect the peak power changes in the RF put into it, and this can result in poor audio. For example, if you pump 500 watts carrier into a short Firestick with roughly 500watt peak antenna handling capability, then as soon as you modulate, the 500 watt increase in RF (modulation sidebands in AM, or sideband power in SSB) into the antenna will heat that bad boy up and not translate as well into the Ether (over the air). That peak power ramping of your signal must be accomodated by the antenna in order for the over the air signal to resemble closer to the 1000W peak that you are trying to achieve (closer to legal limit in HAM : ). There I said it, what no one wants to admit, but yet we witness it with big power stations who put out tremendous "perceived audio" due in parts to every component in their system having the ability to condition the final intended "over the air" signal. Good luck with your system, there are many parts to it and the more attention paid ($$$, elbow grease, technical thinking, perseverance), the better your system will perform. Very Best Regards

[jessejamesdallas]

Which is better..Flat or Round? Or just a plane ol' Whip?

Here's what CB Magazine found....

http://www.cbradiomagazine.co ... %20you.htm

[throttlerod]

Ok so, I read this post somewhere today (don't think it was here) where they had taken a Preditor and mounted it horizontal above the cab of their truck. As i am still (always) learning about , well, most everything that I do, I thought I would get the opions of the folks here.

So horizontal mount VS the standard Vertical mount. Coiled or non.

[Crisco]

so is there a hard fact answer or is it just more or less prefrence?

[jessejamesdallas]

Ok so, I read this post somewhere today (don't think it was here) where they had taken a Preditor and mounted it horizontal above the cab of their truck. As i am still (always) learning about , well, most everything that I do, I thought I would get the opions of the folks here.

So horizontal mount VS the standard Vertical mount. Coiled or non.

So are you talking about mounting the antenna side-ways or like some of the truckers do and mounting it at a angle "Bull-Horning"?

Never seen one mounted horizontally or "side-ways" so I assume your talking about Bull-Horn mounted.

Most mount antenna's that way because of height restrictions, because otherwise the antenna would be hitting something all the time either where they are getting loaded, or because of local law enforcement on height...Others do it because they think it looks cool. Regardless, tilted like that would have a effect on the over all performance...Just how much, I have no idea, but the antenna is going to be radiating the signal in the wrong direction if it's tilted...

If tilting a antenna made it work better...then you would see Radio Towers that looked like the Leaning Tower of Pisa all across the Country!

[352 Smiley]

both are good antnnas

[StrykerLiker]

I don't know if this is indicative of all flat coils, buttt. Ever since I put a workman viper on my truck I have been been hearing some humming noise. I didn't relate the 2 until today. I had some suspension work done at same time.

After changing to a more sturdy mounting stud yesterday . The noise got insanely load. It sounds like my motor is kidnapping an opera soprano.

I rested my elbow on the Window seal to look out at my tires. And feel the vibration in tune with the sound. Then I look at my antennas coil and is vibrating violently up and down. On all wraps. Very fast like a hummingbirds wings. Only when doing 40-45mph.
It basicly turned my antenna mirror arm and door into a giant tuning fork. I will take a video next time it happens. Maybe it's why the guy sold it to me for so cheap.


Sent from my Deelybobber using Tapamajigger

[MDYoungblood]

That is an easy fix, just turn the whole antenna a 1/4 turn, that changes the windload on the antenna, you haven't been the first to turn your mirror into a tuning fork.

3's

Greg

[StrykerLiker]

LoL. I have tried turning it now. Thanks. I found a spot where it vibes much less violently. But still there. I'm gonna get a predator and use the viper on the roof of my pimpin station wagon, and hope for better results.

Sent from my Deelybobber using Tapamajigger

[jessejamesdallas]

LoL. I have tried turning it now. Thanks. I found a spot where it vibes much less violently. But still there. I'm gonna get a predator and use the viper on the roof of my pimpin station wagon, and hope for better results.

Sent from my Deelybobber using Tapamajigger

Predators will do the same thing...Trick is, mount the antenna so that where the coil attaches to the insulator, is facing forward, and not to the sides...some times all you need to do is add a washer between the antenna and mount...You can experiment with different thickness's of washers to find one that makes the antenna face the right way...some times it may take two washers, or loosen the antenna mount and rotate it till you can get the antenna in the right position.

If you think it's loud now with it sitting out on the mirror bracket...You ain't herd nothing yet! Get one humming on the roof, and the whole roof turns into a giant speaker!

['Doc]

And since it all deals with mechanical vibrations, change it mechanically and you might get rid of the 'bad vibes'. One way of doing that is by tying a piece of string/ribbon to the antenna, let it flutter in the wind. What length of string/ribbon? Beats me, start off sort of long and trim it. I'd recommend pink ribbon though...
- 'Doc

[jonmerritt]

Flat coils do nothing over round coils. It is a loading coil is all it is. Using flat material only makes a larger coil, and does nothing to improve your signal or audio. It is a loading coil and a sales gimmick. Anything else is pure crap and made up.

[cbdon]

From what I understand about large coil antennas is that coil antennas have a broader bandwidth then a 1/4 wave antenna are suited to more frg then just 11 meters, output is no better. but efficacy is 95% according to test done, this is from a article I read on the internet, dispelling myths about coil antennas. Apparently a truck driver invented it after becoming upset with breakage using his 1/4 wave he had been using, according to the article. At the time he had no experience with antennas, made just what look good to him at the time, now with experience making antennas he uses a technical approach when he makes them, I be-leave it is the monkey antenna and others that he makes. if anyone is interested in this type of antenna they should read this article as it is very interesting.

[The DB]

From what I understand about large coil antennas is that coil antennas have a broader bandwidth then a 1/4 wave antenna

Adding an inductive load (or a coil) to an antenna will narrow the antenna's bandwidth. Adding a capacitive load (or a cap hat) will widen the antenna's bandwidth.

All methods of shortening the antenna will also add loss, which universally widens the antenna's bandwidth to a point, but this rarely makes up for the narrowing effect of a coil.

Most longer large coil antennas have large enough coils that there really is no discernible difference between their bandwidth and 1/4 wavelength antenna's bandwidth. A change in environmental conditions, such as driving a vehicle with a mobile antenna, will have more of an effect on the antenna's bandwidth than the small difference in length of most large coil antennas compared to a full length 1/4 wavelength antenna.


The DB