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Charliebrown
Intermediate Member
Username: Charliebrown

Post Number: 208
Registered: 10-2002
Posted on Monday, June 27, 2011 - 2:05 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

IN REAL MEASUREMENT WHAT IS THE REAL DIFFERENCE BETWEEN AN ANTENNA THAT CLAIM'S TO HAVE 9.9 DBI GAIN AND ONE THAT CLAIM'S TO HAVE 5 DB GAIN? I THINK THAT 9 DBI = .8 DB IN ACTUAL GAIN. IS THIS RIGHT? IF NOT PLEASE INFORM ME OF THE ACTUAL DB DIFFERENCE BETWEEN THE TWO.
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Tech833
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Username: Tech833

Post Number: 1998
Registered: 8-2002
Posted on Monday, June 27, 2011 - 12:48 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

We need to know which antennas you are talking about before we can give you the "actual DB difference between the two".

By the way, dB gain "claims" are just that. Not real. I can say that a 1/4 wave ground plane has 100 dB gain, and even print it on the box and instructions. But, it doesn't make it true. Unfortunately, nobody has ever held hobby antenna makers liable for their claims.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown

Post Number: 209
Registered: 10-2002
Posted on Monday, June 27, 2011 - 5:53 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I know that from past conversation's that there is not much difference between two different 5/8 wave antenna's. But I was making reference to the i max 2000 dbi and the maco 5000 db gain claim's.
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Tech237
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Username: Tech237

Post Number: 1452
Registered: 4-2004


Posted on Monday, June 27, 2011 - 6:57 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Add to what Tech 833 says any gain stated that doesn't state if it's referenced to a dipole, isotropic antenna or other specified comparison is just so much garbage.

The same antenna can be quoted as having two gains - one compared to a dipole and one compared to theoretically perfect antenna in free space, and they would be an approximately 2.3dB difference in ther figures _ IF the person quoting is being honest .
Tech237
N7AUS

God only made some many perfect head, on the rest he put hair.
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Sitm
Intermediate Member
Username: Sitm

Post Number: 448
Registered: 1-2004


Posted on Tuesday, June 28, 2011 - 9:27 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

A DISCUSSION OF ANTENNA THEORY
by Paul Graham (K9ERG)
1. ANY piece of conducting material will work as an antenna on any frequency.

Even a straightened paper clip will work on 160 Meters. All we have to do is properly match the the transmitter to the the paper clip, and the paper clip will radiate ALL of the power fed to it! The aperture of this antenna will have a radius of 5/32 wavelength (.079 sq. wavelengths cross section area); essentially this is close to the theoretical "Isotropic" source. If this antenna is located in "free space", the radiation will be almost equal in all directions.

2. The ONLY reason for building sophisticated antennas is to allow us to CONTROL THE RADIATION PATTERN.

The radiation pattern is controlled by focusing the radiated energy. The geometry of the antenna and the proximity of near-by objects are the main controlling factors.

The total amount of energy radiated remains constant for a given transmitter output power. When this energy is focused, the energy radiated in one or more directions will be increased, and the energy radiated in other directions will decrease. This is what gives an antenna "gain".

3. An antenna has an aperture similar to that of a camera lens. The aperture of an isotropic source is a circle with a diameter of 5/16 wavelength.

The aperture of a dipole antenna is roughly the shape of a rugby ball (elliptical) when viewed from a point 90 degrees from the line of the conductor.

The cross section area of the aperture of a dipole is 1.64 times that of an isotropic source.

When A1 = aperture of a dipole and A2 = aperture of an Isotropic Source:


Gain = 10 LOG(A1/A2) = 10 LOG(1.64/1) = 2.15 dB.


4. The Dipole antenna.

Contrary to popular belief, the dipole is so named because it has two electrical poles, not two physical poles; it also has two zeros and could have been called a di-zero antenna. When the length is such that the poles are at ends of the conductor and the zeros are at the center, the antenna will be exactly 1/2 wavelength long.

Therefore:
A dipole antenna is exactly 1/2 wavelength long.


A dipole is most commonly fed at the center, where it presents a pure resistive, balanced, 68 Ohm (R68j0) load to the feed line (this is why the popular misconception of two physical poles).

A dipole can be fed anywhere along its length, however CENTER FED and END FED are the most common, and the easiest.

5. The effects of APERTURE INTERFERENCE.

Anything that enters into the aperture of an antenna will affect the operation of the antenna. The effects are pattern distortion, skewing of balance, change of feed impedance and resonant frequency shift; in other words - everything we want to control.

Sometimes it is desirable to cause intentional aperture interference. Placing other conductors into the aperture will cause severe pattern distortion. This can be beneficial when this distortion takes place in such a manner as to focus the radiated energy into a tight beam. This is the basic operating principle of parasitic beam antennas.

6. Ground mounted vertical antennas.

One common practice is to mount one half of a dipole vertically on a conducting surface (ground plane). This reduces the size of the aperture by 50%, resulting in a 3 dB loss. As we have seen, a dipole has 2.15 dB gain over an isotropic source; if a 1/4 wavelength antenna on a ground plane has 3 dB loss as compared to a dipole, that means that the "1/4 wave" antenna has 0.85 dB loss as compared to an isotropic source. Some antenna manufacturers express the gain of their products as "gain over a 1/4 wave". An antenna advertized as having 3 dB gain over a 1/4 wave is the same as as an antenna having 2.15 dBi gain or 0 dBd gain. It's the same antenna - the bigger numbers are just that - bigger numbers!

A somewhat less common practice is to mount a vertical dipole directly on the ground. This practice is fraught with problems. A portion of the aperture is beneath the ground. This induces large currents into the ground surrounding the antenna. With the high (and uncontrollable) ground resistance, these currents result in substantial voltage drops. The power lost to heating the ground does nothing more than make the worms uncomfortable. These losses can be reduced to acceptable levels by installing an extensive ground system (90 - 1/2 wavelength long radial wires placed on the ground at 4 degree spacing is about minimum). The severe aperture interference also causes the antenna to exhibit a high angle of radiation. It would be easier (and cheaper) to elevate the antenna far enough so that the aperture does not touch the ground.

7. Elevated vertical antennas:

One attempt at elevating a dipole antenna resulted in what is commonly known as the 5/8 wavelength vertical antenna. The theory goes something like this:

"If we elevate a dipole antenna 1/8 wavelength above ground, the aperture will just touch (or just miss) the ground. We can feed the antenna with 1/8 wavelength of high impedance feed line (a single wire should work) and the ground loss and radiation angle problems will disappear."
Actual construction of these antennas is such that the antenna conductor is continued on down to the ground, where a matching network transforms the high impedance of the 1/8 wavelength long, single conductor, feed line to the low impedance of the line running to the transmitter. The resulting structure is 5/8 wavelength high (hence the common name).
Alas, it does not perform as expected. There is considerable mismatch between the antenna and the high impedance, single conductor feed line, resulting in radiation from that line. This would not be all bad except that this radiation is in the wrong direction (30-45 degrees up depending on ground conductivity). This approach also did not eliminate the need for an extensive grounding system. Because this antenna does exhibit some gain (approx. 2.9 dB) over a 1/4 wave whip, it has become a sort of de-facto standard for VHF and UHF mobile operation.

Another approach to the problem is the "J-Pole" antenna. In this design, the antenna is elevated at least 1/4 wavelength above ground, thus eliminating the ground losses and "normalizing" the radiation pattern. The Impedance matching between the low impedance feed line and the high impedance of the end of the dipole is accomplished with an open wire stub matching network. A shorting bar is placed at one end of a 1/4 wavelength of open wire line, the dipole is then connected to the open end, and the feed line is connected at the point where the impedance of the feed line matches the impedance of the stub. If Co-axial cable feed line is to be used, a BalUn MUST be used. Attempts to feed this antenna directly with co-ax have met with disastrous results. The 0 Ohms reference point is at the center of the short, NOT somewhere up the side of the "J".

Yet another workable solution to the problem is to use a co-axial stub matching network. The advantages of this approach are that it can be fed directly with co-axial cable, a large reduction in wind resistance making it suitable for mobile operation and its total independence from ground. The major disadvantage is the extreme difficulty of construction. Unless special (expensive) tooling and fixturing is available, it is almost impossible to assemble the matching network! Although it can be done, this antenna is easier (and much cheaper) to purchase (mass produced) than it is to build just one!

8. The PROPER and COMPLETE match.

The match between an antenna and its feed line is only proper and complete when the following conditions are met:

a. The antenna impedance is matched to the feed line impedance. The only "right way" to do this is to use a matching network between the feed line and the antenna. ANY adjustments made to the antenna in order to achieve impedance matching will change the radiation pattern of the antenna.


There is one notable exception to this: When we want to achieve an impedance transformation, we can insert a short (usually 1/4 wavelength long) piece of feedline that will have a VSWR greater than 1:1.
b. The antenna balance is matched to the feed line balance. When feeding a balanced antenna, a balanced feed line MUST be used. Conversely, when feeding an unbalanced antenna, an unbalanced feed line MUST be used. When it is necessary to mix balances, a BalUn MUST be used. This can be incorporated into the design of the matching network.

9. 1:1 VSWR does NOT indicate resonance.

The Voltage Standing Wave Ratio (VSWR) is only the ratio between the impedances of the feed line and the load.

If we connect a 50 Ohm resistor at one end of a piece of 50 Ohm co-axial cable, and connect a transmitter and SWR meter at the other end, the VSWR will be 1:1. The resistor is NOT, by any means, resonant.

If we connect a resonant antenna that has a feed impedance of 272 Ohms to the end of that piece of co-ax (ignoring any resonance effects of the co-ax), the VSWR will be 5.44:1.

It is possible to cut a piece of feed line to just the right length, and measure a 1:1 VSWR at the transmitter end of that feed line -- the actual VSWR on this line is (infinity):1.

The only practical way to measure the resonant frequency of an antenna is to use a DIP METER at the antenna.

10. High VSWR does NOT cause feed line radiation.

Most radiation from co-axial cable is caused by terminating this unbalanced feed line with a balanced load. The remainder of the radiation is due to other problems such as: dis-continuities in the outer conductor (braid corrosion is a major factor), improperly installed connectors and signal pickup caused by routing the feed line too close to, and parallel to the antenna.

Contrary to popular belief, properly terminated and installed open wire line does not radiate. Even with infinite SWR, the fields surrounding each wire cancel each other at a distance roughly equal to the wire spacing distance away from the line. Terminating the line in an unbalanced load, or causing anything to come within the "field space" will cause unbalance in the line, thus allowing the line to radiate.

11. Antenna Gain Information.

There are four ways of expressing antenna gain. These are:


dBi Gain over an isotropic source (a theoretical antenna having no dimensions: a geometric point).
dBd Gain over a dipole (0 dBd = 2.15 dBi).
dBq Gain over a quarter wavelength whip (bigger numbers than dBi).
dBadv LARGE RANDOM numbers generated by the advertizing and marketing departments at some antenna companies. These departments are sometimes known as the "S and M" (Smoke and Mirrors) groups.

Sad to say, but the advertized gain claims of most large antenna companies are out and out fraudulent. Because most users of antennas can't separate the real numbers from the phony, they wind up paying big money for junk and the honest antenna companies suffer. With lower sales, the honest companies have smaller R&D budgets. New and better products don't get produced. Everyone loses. (End article)

Do your homework on antenna reviews and read actual owners opinions in mass. I have found that once in the amateur radio venue the gains are closer to factual performance due to the fact that operators are more inclined to know the difference between claimed gain and actual gain during operation. Giving false gain claims to a structured group can deminish there desire to purchase said equipment as operators lose faith in the company.

In the end, do your homework, don't believe manufacture claims especially if the company isn't well established.
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Sitm
Intermediate Member
Username: Sitm

Post Number: 449
Registered: 1-2004


Posted on Tuesday, June 28, 2011 - 9:30 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

(provided by author, not myself, but good stuff)

"Antenna Myths"

Or, making sense of confusing gain claims......



One of the most confusing and embellished aspects of CB equipment advertising, are antenna gain ratings. Most CB'ers, by definition, are continuously looking for ways to better their signal and, by extension, their status among their radio peers. One of the easiest and most effective ways to improve one's station is through the antenna. A well made gain antenna, can wake up a formerly marginal signal. Manufacturers are well aware of this, and they also exploit the general lack of solid technical background possessed by most CB'ers. They take advantage of this void in technical know-how to make inflated, questionable, and vague claims about their products for the sole purpose of attracting people and making sales. Some antenna makers use little gimmicks to justify their extra gain numbers. While more knowledgeable people may question the ethics of such practices, it has nonetheless continued even to this day. When evaluating a CB antenna purchase, it is helpful to make comparisons to similar amateur and commercial antennas. Do these antennas utilize these same "gain" enhancing "gimmicks"? Shouldn't it be logical to assume that any tried and true method for increasing performance would be utilized in antennas for other services? So why then, does this "magic" only work on CB?

At this point, it is also helpful to separate base station from mobile antennas. Since mobile antennas become structurally impractical if they exceed a physical 1/4 wavelength, it becomes difficult to achieve any appreciable gain, so gain ratings are rarely given for a mobile antenna, (since there usually isn't any) other than vague references such as; "Transmits 20% farther" (Farther than what?). For this reason, this discussion will be limited to base station antennas, where gain figures are commonly (mis)given.

Like I've said before, CB'ers are drawn to the biggest and best equipment. So with this in mind, many antenna manufacturer's marketing departments took a broad amount of liberty in making performance claims. Since it was not likely that the average CB'er would be taking the companies to task for misleading ratings (Another reason why ham and commercial antenna makers are less flamboyant with their gain claims), it was open season for wild advertisements to commence, much to the chagrin and consternation of the CB consumer, who's only looking for the best possible performance for the money he has.

Will the real db please stand up.....

One of the most common terms that is associated with antenna gain is the "db". db stands for "decibel", and it is a unit of relative power. For a db to be meaningful however, it has to be compared against a known standard of some sort. Simply saying that a particular antenna has "18 db of gain" is meaningless unless we know what it was compared against. 18 db compared to a standard 1/2 wave vertical? A 1/4 wave GP? A coat hanger? A wet noodle? Hopefully you get the idea.

It is this little ambiguity which allows some manufacturers to inflate their claims, and yet still claim to be telling the truth even when the smoke and mirrors of their measurement methods, and of their reference is revealed.

There are some engineering standards which are commonly used when comparing antennas. The 3 most common standards are dbi, dbq, and dbd.

dbi is in reference to an isotropic, theoretical antenna which radiates equally in all directions in a spherical pattern. This however, is not possible in practice.

dbq is a reference compared to a quarter wave vertical. The "gain" of a quarter wave falls somewhere between that of an isotropic radiator, and that of a half wave dipole. This standard is not as popular as dbi and dbd.

dbd is the most truthful of standards. It is referenced to a real 1/2 wave dipole antenna, which is one of the most basic antenna designs. A dipole has a "gain" of about 2.14dbi, or 0 dbd..

With these standards in mind it should be easy to see that an antenna with a rated gain of 4dbd is "stronger" than another antenna with a rated gain of 6dbi. Yet without the reference figures, one could be fooled into thinking that "more is better" and that the higher number is automatically the stronger antenna.

Because of the nature of CB and the desire of manufacturers to make their products look as big (or bigger) as they can be, most CB antennas are rated in terms of dbi (Of those who are actually somewhat honest).



And if you're not already confused.......

So now that we know what these standards mean, what does this mean in the real world?

Vertical antennas are normally derivatives of either 1/4, 1/2, 5/8, or 3/4 wave antennas. We've already determined that a 1/2 wave dipole has a gain of about 2.14 dbi. So why then do other 1/2 wave designs (such as the 1/2 wave ground plane), advertise a gain of up to 3.75 dbi? Much of this can be explained by another phenomenon of antennas; radiation angle or pattern. An antenna does not radiate equally in all directions (unless it's a theoretical isotropic radiator), so there will be some places where it will be stronger than others. Generally speaking, the higher the gain of a vertical antenna, the narrower its radiation pattern will be. When comparing the realized gain difference between 2 different antennas, gain figures could vary considerably depending on which angle the comparison is made at. Manufacturers can then compare apples to oranges by comparing the gain of the reference in a place where it is not at its peak gain, against their product, which performs better at that angle. This may or may not translate to better performance for the average user, but it does give them some grounds to defend their often inflated gain claims.

The other factor to consider is radiation angle. This refers to the angle in degrees above the horizontal plane, which the major radiation lobe is concentrated. Generally speaking, the lower the radiation angle, the more useful power is being sent in the desired horizontal direction, and not into the sky. But this is not always cast in stone. Because of irregular terrain, and things like mountains and valleys, one particular antenna, with a higher radiation angle, may perform better against a superior design with a lower radiation angle. For those who pursue DXing, a higher radiation angle may actually be preferable for shorter skip zones.

The highest gain vertical configuration, which still offers a fairly low radiation angle is the 5/8th wave vertical GP. The 5/8th wave has about a 1.85dbd gain, which equates to about 4dbi. 3/4 wave antennas can achieve slightly better gain, but at the cost of a higher radiation angle, which is why they are seldom seen. On CB frequencies, be especially skeptical of any non directional vertical which advertises anything over about 4.5dbi gain. You just can't get there from here.

On VHF and UHF frequencies, where primary radiator length is greatly reduced, there is another technique which is commonly employed, to increase gain, and that is known as a "colinear" configuration. A colinear antenna is simply multiples of either 1/4, 1/2 or 5/8 wave elements stacked on top of each other, and kept in phase by utilizing a coil between sections. This allows the antenna to achieve gain values of up to around 7 or 8 dbi or more depending on the number of segments in the array. The number of segments is normally limited only by physical antenna size. You can have 16, 1/2 wave segments at 900 Mhz, and still be under 9 feet long. However, the downside to a colinear antenna is that they achieve their extra gain at the expense of greatly narrowing the E-Plane radiation pattern, which can then produce dead spots in areas which fall above or below the main lobe of the pattern. To visualize this phenomenon, think of a 1/2 wave dipole antenna as radiating in a pattern in the shape a donut. Then take a flat piece of metal, and slowly squish the donut nearly flat. Notice that the diameter (gain) of the donut will increase, but the height (radiation pattern) will become narrower. This is what essentially happens when you utilize a colinear antenna array.

This technique is not practical for a CB antenna, due to the size required. If a 5/8th wave is around 20 feet at 27 Mhz, imagine a colinear antenna, which has 4, 5/8 wave segments. I don't think an 80' tall antenna would be very practical or structurally sound.

So, in conclusion, if you believe that an Antron 99 (which is simple end fed 1/2 wave) really has 9.9 "db" of gain, or that an A/S Starduster (which is only a 1/4 wave radiator) actually has 5 db (At even the dbi standard) of gain, then I have some swamp land in Florida that I'd like to sell you.
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Charliebrown
Intermediate Member
Username: Charliebrown

Post Number: 210
Registered: 10-2002
Posted on Tuesday, June 28, 2011 - 2:17 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

O.K. WITH THE VERY GOOD AND VERY HELPFUL INFORMATION PROVIDED BY SITM AND THE TECH'S AND FINDING OUT THAT MOST THAT MAKE THESE ANTENNA'S LIE. WHAT COMPANY DO YOU THINK IS HONEST AND CAN BE TRUST WITH THE CORRECT SPEC'S?? BY THE WAY SITM, THANK YOU FOR THE TIME AND WORK TO GIVE US THIS VERY INTERESTING INFORMATION. I AND OTHER'S WILL FIND THIS INFORMATION TO BE VERY HELPFUL. SITM, WHAT DO YOU THINK IS A VERY GOOD ANTENNA? BEFORE I GO I WANT TO THANK THE TECH'S FOR THEIR HELP AS WELL. WHEN YOU LOOK AT DB, DBI, DBD AND SO ON I GUESS IT IS SNAKE OIL TO MAKE A SELL.
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Dale
Senior Member
Username: Dale

Post Number: 1726
Registered: 12-2002
Posted on Tuesday, June 28, 2011 - 10:03 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

nice post thanks. now goitta read it again cause ya done confused me long time ago
dale/a.k.a.hotrod
cef426
cvc#64
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Sitm
Intermediate Member
Username: Sitm

Post Number: 452
Registered: 1-2004


Posted on Wednesday, June 29, 2011 - 2:40 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

What antenna is best is an open ended question. The question probably should be "what antenna is best for me". There are many variables to selecting a proper antenna for yourself. Such as:

What is the immediate terrain in my region?
What will I be using this antenna for? Local communications, long range or short range skip conditions?
What power rating will I need, what power will I be using?
How high will my antenna be mounted?
Are there obstetricals in the direct path of my antenna transmit path?
Will you be above 33.5 feet or below 33.5 feet?
Will I be utilizing this antenna 10, 11, 12 meter or just 11 meter?
Am I surrounded by other high power stations who are causing "bleed over"?
What is my price range?
How difficult of an installation can I complete?
Can you construct an antenna that comes in pieces and needs assemble?

I would say that the best antenna is the one that you decide to use after carefully reading many many reviews. The antenna you choose after you have read actual test review articles to determine which antenna suits you best for all the variables that are mentioned above.

In the end the very best antenna is the one in the air broadcasting on the frequency that you intend to broadcast on.

Make an educated decision on the antenna that will work best for you. Utilize the hundreds of sites that will give you technical information on the antenna you are interested in.

Be cautious that you don't put too much merit in one review or one opinion. Look for patterns in either good reviews or bad.

Remember there aren't going to be very many people that have used dozens of antenna and can compare them to one another. And only a very select few of those people are going to have access to a test range where conditions are controlled so that a correct comparitive test can be conducted.

Your best source of information in determining what antenna is best for you is you. Obtaining information on the antennas that you are interested in and that have a history of good performance and value.

I personally use a Sirio D-27 and a Imax 2000 at two different stations in my home. Would I purchase these antennas again, absolutely. I read dozens and dozens of reviews on these antennas before making my purchase. Are they the best? I don't know, but they are the best for my particular needs and situation without a doubt.

Remember, don't purchase what someone tells you is the best, purchase what is best for you and your particular needs and situation and get on the air.
--
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Charliebrown
Intermediate Member
Username: Charliebrown

Post Number: 211
Registered: 10-2002
Posted on Wednesday, June 29, 2011 - 10:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

THANK YOU SITM, I HAVE AN I MAX 2000 WITH THE GPK AND IT IS ABOUT 30 FOOT IN THE AIR. I LIVE WITH VERY HIGH MOUNTAIN'S AROUND ME AND I HAVE MY ANTENNA AT THE TOP OF THE MOUNTAIN WITH ABOUT 500 FOOT OF LINE TO THE ANTENNA. FOR NOW I HAVE THE P3 750 75 OHM LINE GOING TO THE ANTENNA AND I AM IN THE PROCESS OF GOING TO 50 OHM WITH ABOUT THE SAME LINE LOSS. IT WORK'S FOR ME. HAVE A GREAT DAY SITM. CATCH YA LATER.
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Dale
Senior Member
Username: Dale

Post Number: 1727
Registered: 12-2002
Posted on Thursday, June 30, 2011 - 1:50 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

thanks sitm.. ive been looking into the sirio
d-27.just curious are you using for horizonal
operation?if yes how good it do?right now money
too tight for a 3 element beam plus rotar and all
dale/a.k.a.hotrod
cef426
cvc#64
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Sitm
Intermediate Member
Username: Sitm

Post Number: 453
Registered: 1-2004


Posted on Friday, July 01, 2011 - 9:34 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I have used it for both and it works as you would expect for a single element horizonal but as a vertical I have been exceptionally impressed in fact it is 20 feet lower than my Imax at the radio room on the west portion of the house. The Imax has 2995, Sirio D-27 has the 2950 and I see as good or better performance from the Sirio. Initially I purchased it because I needed a side mount off the tower due to the 2 meter at the peak and have been very impressed with it. I have to admit that I was skeptical of the antenna until it arrived in by ups from Copper and found the quality of build and easy of construction. I would have to say that this is one antenna I would buy again and has given me reason to purchase the four element Sirio beam from copper as well. The D-27 works well as horizonal but you will have north/south or east west directional transmit/receive depending on which way you piont it. Not an enormous deal of side rejection but that isn't want it is designed for.
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Dale
Senior Member
Username: Dale

Post Number: 1729
Registered: 12-2002
Posted on Friday, July 01, 2011 - 3:28 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

well that sounds good.i got a sirio 2016
antenna from copper back in 09 still up
and kicking. at 20 feet long it seems every bit
as good as the imax 2000 if not slightly better
and was just as easy to setup.i thought the
d-27 would make me a great little flatside.
dont see any reason for two veticles why i was curious about flatside.i havent seen it listed in coppers though????
dale/a.k.a.hotrod
cef426
cvc#64
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Sitm
Intermediate Member
Username: Sitm

Post Number: 457
Registered: 1-2004


Posted on Friday, July 01, 2011 - 4:54 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I purchase from several differenc sources, I may have my companies confused. Do a google search you will find it, maybe we will prompt them to carry it in their inventory.

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