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General discussion

Wireless Antennas---worth it????

Feb 17, 2004 3:27PM PST

Do these replacement antennas (D-link) that extend the height of the existing antennas, do they just increase range or will they also boost the signal or improve the signal? Thanks

Discussion is locked

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Re:Wireless Antennas---worth it????
Feb 17, 2004 9:54PM PST

"Do these replacement antennas (D-link) that extend the height of the existing antennas, do they just increase range or will they also boost the signal or improve the signal?"

1. Increase range.

Yes. But not as far as people may want. Certainly not 2X...

2. Boost the signal.

No. It's an antenna. The amount of energy is the same in the amplifier so that's not it. The antenna has less loss so that will give it more efficient output. But the reception is better, so that helps on the recieve side.

3. improve the signal?

Doubtful.

For transmission, the signal "quality" is more about the good design of the transmitter and how well the antenna and complete system is matched. So my answer is no.

For reception, a real problem of a more sensitive antenna is you also amplify any other signals in the area. If you have interfering signals, then a better move is to change the RF channels and try again. For reception, my answer is "doubtful" to this factor.

Bottom line? Try it.

Bob

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Re:Wireless Antennas---worth it????
Feb 20, 2004 4:02AM PST

I'm going to have to disagree with the other response here on several points.

Yes, dependent on the type of antenna you use, an antenna can boost the signal (by giving it gain) as well as increase the range.

There are several points to consider here. You're not going to increase the actual number of watts of power coming out of your wireless card, but by choosing the antenna to suit your purpose, you can increase your effective radiating power depending on the antenna you use.

If you're only looking to boost the range within say an office or your home, then a small "stubby" omnidirectional antenna will do the trick just fine.

If you have something more elaborate in mind, say sharing your wireless connection with a neighbor or over longer distances, you're going to need a more directional antenna that you will essentially point at the location you're trying to hit. This type of antenna can take on several forms either as a "waveguide" or "yagi".....you can build one very inexpensively. Check out the following article for a simple tincan waveguide antenna:

http://www.turnpoint.net/wireless/has.html

Also, check out Hyperlink Technologies. They offer a number of inexpensive solutions and also sell the pigtail wire you will need to connect your wireless card to whatever antenna you end up using.

Good Luck

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I stand on the laws of thermodynamics.
Feb 20, 2004 4:17AM PST

How can your antenna boost the signal?

I did indeed note that antenna would have less loss, but since it's a passive device, where did the gain of energy come from?

Bob (being picky about this or that.)

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Antenna Gain
Dec 20, 2004 2:23PM PST

Any transmitting antenna can provide gain on a transmitted signal over a standard groundplane antenna. Gain antennas such as a Yagi Beam most certainly will offer the advantage of increasing the strength of a transmission. This is the reason why TV and Radio stations use a variety of antennas to increase the effective radiaion power of their stations. It's not a thermodynamic principle it's a basic principle of radio transmissions. If you study radio theory, I think you'll find that what I'm saying is true.

RadioActive1

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antenna gain
Jan 28, 2005 8:51AM PST

There are principles in RF transmission that most people aren't aware of, or taught. I will try and put it in simpler terms.

When people or companies talk about higher gain antennas, you have to realize antenna's do NOT generate GAIN at all. You have different types of antennas - omni-directional, and directional (Yagi's, inverted vees, dishes)antennas. When you have someone say their antenna has more gain, it is because it's a directional antenna. They compare it to a standard omni-directional that radiates RF energy in a 360 degree pattern. So if you have a directional antenna that concentrates received/transmitted RF from/to an area within a 30-45 degree span, it will show a stronger signal strength (therefore a higher gain).

Just because an antenna is bigger, that doesn't mean it's better. All antennas are built to a 1/4 wavelength of the frequencies it uses. So the antennas are built where they can be used in the VHF, UHF frequencies (sort of broadbanded)

VHF and UHF are line-of-sight frequencies, so the less obstructions the better.

I hope this explained things a little better.

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Antenna Gain
Dec 3, 2005 9:06PM PST

You are correct on many of your points here, however, I wanted to comment on a couple of things you said.

True antennas do not "generate" anything. They are passive devices from a power-generating perspective, but they do provide gain based on how effectively they radiate the power of the transmitting devices. All antennas are (or can be) rated in terms of Gain, measured in Decibels (or db).

To say that only directional antennas have gain is not true. And to say that all antennas are 1/4 wave is also not true. I have a full-wave HF antenna strung around my backyard. Compared to a simple 1/2 wave dipole it provides somewhere on the order of 3-5db gain over the dipole. Vertical antennas can be 1/4, 3/8 wave or even full wave (although for some frequencies this would most certainly be impractical).

The reason a full-wave antenna has more gain than say a 1/4 antenna is simple - more energy is effectively being radiated off the end of the antenna.

Good information presented here - just a few minor "tweaks".

RadioActive1

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No gain. Less loss.
Jan 28, 2005 11:23AM PST

To get a gain, one must introduce energy. Where does this energy come from?

If you just write it's less loss, then we are done.

Bob

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Antenna Gain
Dec 3, 2005 8:31PM PST

Again, it's not about thermodynamics. It's about making the most effective use of the energy you have.

An omnidirectional antenna radiates energy equally in all directions, or as some would say "radiates equally poorly in all directions". This is true of groundplane antennas in particular, but also of simple dipoles which radiate energy to the sides with the primary radiation lobes being perpendicular to the orientation of the antenna (i.e. if your dipole is oriented North/South, then you're best trasmit/receive pattern will be East/West). A dipole antenna is the type of antenna that comes packaged with most stereos/receivers and looks like a flat piece of wire in the shape of a "T".

A Yagi antenna is basically a dipole with a reflector (being slightly longer than the element that the coax or antenna wire is connected to) and one or more directors. In this way the reflector and director elements focus the energy in one direction. When you see a T.V. antenna, this is in effect a type of Yagi or "beam" antenna. This is why when you install a T.V. antenna you have to point it in the same general direction as the television stations you are trying to receive.

The type of antenna used in your car is a basic omnidirectional groundplane with the groundplane that the antenna works off of being the car body itself.

So, bottom line - it's not about generating more energy, but about making the most effective use of the energy you have.

It's also true that "size matters" to a degree, i.e. - a 1/4 wave (an antenna that is 1/4 of a wavelength of the design frequency) will be less effective for transmission and receive than a full wave antenna.

All of this is just basic antenna theory, nothing more.

For more information on antennas, designing antennas (which is very easy to do in many cases), try the ARRL web site:

http://www.arrl.org/tis/info/antheory.html

Hope this helps.

Radioactive1

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antenna gain
Mar 19, 2005 5:41AM PST

I think, radioactive1 is right. Every antenna, whatever shape and design, has a gain coefficeient that characterzes it. The energy that all antennae use is picked/catched from the surrounding environment. There are antennas that pick the signal from air, from water (incl. see water) and the ground as well. The application of antennae signal input/output could be used in common radiotransmmition and communication (all means) as we perceive it in a plain understanding and/or for a large variety of professional/technical applications such as medicine, geology/geophysics, cosmonautics and so on...The signal could be of a natural field or a provoked (articially induced) field. Whatever the environment there is a signal (say in the air) radiated (an artificially induced case) by a transmmiter (in mV/m). An antenna catches it and focuses and/or concentrates it, so that on antenna output the signal is more powerful then corresponding its input. The 10 fold log. ratio of output over input of a signal (in principal, whatever the nature of the signal) is called "Antenna's Gain" and is measured in dB (deciBells). Again all that an antenna does is that it concentrates the energy in a specific direction and consequently there is a signal gain that it introduces to next stage/link of an equipment.

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antenna gain
Mar 19, 2005 5:43AM PST

I think, radioactive1 is right. Every antenna, whatever shape and design, has a gain coefficeient that characterze it. The energy that all antennae use is picked/catched from the surrounding environment. There are antennas that pick the signal from air, from water (incl. see water) and the ground as well. The application of antennae signal input/output could be used in common radiotransmmition and communication (all means) as we perceive it in a plain understanding and/or for a large variety of professional/technical application such as medicine, geology/geophysics, cosmonautics and so on...The signal could be of a natural field or a provoced (articially induced) field. Whatever the environment there is a signal there (say in the air) radiated (by a artificial/induced)by a transmmiter (in mV/m). An antenna catches it and focuses and/or concentrates it, so that in antenna output the signal is more powerful then corresponding its input. The 10 fold log. ratio of output over input of a signal (in principal, whatever nature of the signal)is called Antenna's Gain and is measured in dB (deciBells).

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Look at this link link.
Mar 19, 2005 5:52AM PST
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Antenna Gain
Dec 3, 2005 8:47PM PST

You're right, regardless of the antenna type, additional energy (i.e. more than is generated from the transmitter) is not generated.

However, the person that started this conversation aske if wireless antennas were worth it.

You replied that while they increase range, they don't provide as much as most people want. Not sure what you mean by that, but it has been proven that with the right type of antenna that a WIFI signal can be effectively transmitted for a number of miles - yes, you read that right, miles.

You also said that an antenna does not boost a signal. This is simply not true. While the total power out does not change based on an antenna, ERP or Effective Radiated Power is impacted by the antenna. This is why antennas are rated in terms of gain (in decibels) that they provide.

If antennas don't improve signal than why do television and radio stations spend millions putting very elaborate antennas - it's all in an effort to radiate a signal (given the power that the FCC limits them to) as far as possible.

To the gentleman that asked the question - If your objective is to radiate your WIFI signal equally in all directions, than try any number of simple groundplane antennas on the market - several of which provide 5db or better "gain" (the unit of measure used to designate the effective signal boost the antenna provides). If you are trying to direct your signal in a specific direction, try the Cantenna (actually a type of waveguide vs. a true antenna). Do a google search on WIFI antennas or Cantenna (an antenna which is very easy to build yourself).

Hope this helps.

RadioActive1

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antenna gain
Oct 23, 2008 3:11PM PDT

radioactive1 is right.

antennas dont generate power but they certainly transfert power.

one antenna could be so weak and lot of loss in the signal power, whereas one antenna so be so high quality and good to transfer most of the power with minimal loss.

that is why antennas are measured in gain...

remember cheap small antennas only peak a few beams therefore low signal and low gain, bigger antennas would pick up lots os signal so it would have the best coverage and best performance and receive signal with higher gain...

put it this way, put your pc in a corner with desk and lots of things around it, wires, cables etc etc...maybe a blanket....if you notice your reception is so poor and your internet is a bit slower...

because you blocking the signals and very less and minimus signal is received by the antenna....

more signal the antenna receives, more gain and more performance, quicker internet connection or shall I say wifi connection...