How much of a gain does a 9DBi wifi antenna make over a 5DBi antenna

By | May 30, 2012

After getting asked a few times how much of a gain a 9dBi or higher WIFI antenna would have over a stock 5dBi that usually comes with most wireless adapters, I decided to give it a try.

First, I ordered a 9dBi antenna to attach to an Alfa AWUS036NH USB adapter. I then used InSSIDer to give me the strength of the signals coming to me. I made a short video of this which is posted below.

I have to say I was not terribly impressed by the signal gain I made. While it did make some difference, it really didn’t boost my signals as much as I would have thought. With the 5DBi antenna, my router signal strength was around -35 to -40. When I plugged in the 9dBi antenna, it was around -30 to -25.

In short, if you order a 9dBi or better antenna than the 5DBi, then you will see better signal strength but don’t expect a huge gain.

This is the antenna I used, you can read more reviews on Amazon here Alfa 9dBi WiFi Booster SMA OMNI-Directional High-Gain Screw-On Swivel Antenna.

Since buying the 9 dBi antenna I have learned more about range and the effective area an antenna can cover. Here is a picture that illustrates how the dBi effects the range of an antenna. As the picture shows a short 2 dBi antenna will have good coverage for devices that are close while the 7 dBi or 9 dBi are better for distance but not close up.
9 dbi 7dbi 6dbi 2 dbi range wireless

7 thoughts on “How much of a gain does a 9DBi wifi antenna make over a 5DBi antenna

  1. Dean Blake K4DSB

    A long antenna (usually stacked quarter wave sections inside one antenna, sometimes called colinear) increases gain only by ‘folding down’ energy that was shooting up at higher angles by shorter 1/4 wavelength antennas down toward the horizon.. this is extremely effective as the gain is also bidirectional (both receive and transmit benefit) a 3 dbi gain actually is equivalent to doubling the transmitter power (compared to the router on the standard 1/4 wave (short antenna) and 6bdi then would be a quadruple gain in power .. by the way a quadruple gain is double the signal level in voltage terms (i.e. by the formula E squared over antenna impedance)… my experience with a WiFi Gain antennas (especially at 2.4Ghz Band) is that a good 6dbi or 9dbi colinear antenna on the router WILL improve coverage inside the house (signal to noise) and add maybe as much as a few hundred feet distance (workable signal) to your WiFi devices …. best money & cheapest upgrade to any Wifi system.

  2. Rob

    I am having trouble understanding the diagram you posted in the update section. I get that as the dbi of the antenna is increased, the coverage gets better for long distances, but not nearby. What I am having trouble with is understanding the degrees mentioned, because since these are omni directional antennas, the coverage is 360 degrees, and so there is no need for one to point the antenna at a certain angle to get the best reception.

    So, using this upcoming example, and the 7dbi antenna, what exactly occurs here: Let’s say that my router is on a table in the center of the room and I have a laptop with an Alfa adapter and a 7 dbi antenna, and I am about 3 feet away from the table with the router, and I start walking in a 360 degree pattern (so in a circular manner) around that table. How does the 30 degree fit into this scenario? Let’s say I am doing the same thing, but 10 feet away. I get that I would be getting better reception based on the diagram, but again, I am having trouble understanding how the 30 degrees fits into that scenario.

    1. Kevin

      Its referring to the optimal signal reception area. What its saying is that you can plop a 2dbi antenna 6″ away from the transmitter, but 3 feet above it and itll pick up fine because it has a 360deg reception, but a 7dbi placed in the same spot wont pick up anything because its cone of reception is further, but smaller. Think vertical not horizontal (not quite but easiest way to explain it)

  3. Asghar

    EnGenius ERB 9250 Range Expander I feel it is necessary to give my review on theEnGenius ERB9250 2.4 GHZ 300 Mbps Wireless N Range Extender to help others like myself with bad wireless connections. My Linksys WRT600N router blew the 2.4 Ghz circuit (5-6 years old), the 5.0 GHz remained, but this is the signal that doesn’t penetrate walls.

    I now have a new EnGenius ESR 9855G Wireless N, 2.4 Ghz-only router. This is working fine. The remaining content is based on my Linksys WRT 600N wireless router. I have used in the past a Linksys WRE54G G Range Expander b/g with a with a Linksys WRT54G router to the same location. I am currently running 300Mbps with an excellent signal. In the past my Linksys WRE 54 G range expander had a maximum 54 Mbps with a fair to poor signal strength, used in combination with the WRT600N router and a HP premium N adapter. This old setup ran typically 2-20 Mbps with a fair to poor signal.

    I am technical average, below average or novice when it comes to wireless networking. After reading someone’s comment maybe I’m an expert and just doesn’t know it. I have spent hours enhancing locations, changing configurations, and praying for a decent signal. I have by pure accident discovered solutions to problems that no one ever addresses. I’ve come to the conclusion that the advanced techs out there work for the manufactures sales department and really don’t understand wireless systems and their wireless routers. Very seldom can you actually talk with someone. If you do get a hold of someone, they seem to know a lot less than me, which is frightening. I have a home office in a separate building from my home. The nearest exterior stucco wall to exterior stucco wall is 17 feet. I have my WRT600N (now ESR 9855G) wireless router in my family room which is a straight 49 feet from my EnGenius ERB9250 Range Expander in my office. The Range Expander is 7 feet from my computer. The signal is going through 3 walls with windows. I am writing to help people like myself. Number 1 -Important Things That All Web Sites Stress -you can just ignore. You REALLY DO NOT need to pay attention to: 1) line of sight (you shouldn’t have obstacles) between the router and the range expander. They must be living in a tent, but I really don’t know anyone that is so lucky as to not have obstacles i their way. DUMB LESSONS are important lessons or information I have learned creating a decent wireless network and is probably more information than what you need. DUMB MISTAKES are mistakes I made, but because of frustrations, and trying to think logically when I am tired and frustrated; these mistakes have eaten a tremendous amount of my time and were quite easy to fix. Dumb Lesson #1 the 2.4 GHz setting is to broadcast all Wireless N, Wireless G, and Wireless B systems all at the same time on all this same frequency.

    REMEMBER THIS RANGE EXPANDER (WRT600N) IS USING ONLY THE 2.4GHz part of the Wireless Router, not the 5.0GHz. My new router only broadcasts in 2.4 GHz. I originally thought that 5.0 Ghz was only N systems, and 2.4 Ghz was only B or G systems, wrong. 2.4 can be for all three. A, B, G, and N are just standards. N is the most recent allowing higher transfer speeds and more unused frequencies. The frequencies are by far the most misunderstood. Dumb lesson # 2, Misinformation is very prevalent even from known authorities. Just remember, this is part of the problem we all deal with and affects our judgment, when we try to make improvements to our wireless networks. The higher the frequency the more likely it will penetrate walls. This is the complete opposite from what all the wireless geeks say. 5.0 GHz will do better than 2.4GHz going through walls. This is straight from my engineer father-in law who helped put the lander on the moon.

    So ignore what is being said by so called experts, I am a wireless novice with real scientific information. 5.0 GHZ has less distortion from other electronic products in your home. Therefore it has a clearer less obstructed and distorted signal from other household devices. Items that can overlap the 2.4 GHz are: wireless telephones, remote controls, wireless game controls, microwaves, and many more. Ignore this concern. Using a wireless G router, my 2.4 GHz cordless phone blocked all wireless signals. I bought a new DECT 6.0 phone. No more problems. WHY 5.0 Ghz APPEEARS TO BE WORSE is that 5.0 Ghz takes an extremely large amount of power to go the same distance as 2.4GHz, which the best consumer wireless routers don’t have. The router and adapters signals are really going around walls and through windows to best of their abilities. My need has been getting my wireless signal to a far distance with a decent signal and decent speed. The 2.4 GHz is the only way to go with the N standard setting allowing the faster transfer rates up to 300 Mbps and

    1. Matthew

      Hi, interesting comment. You made some correct points, and some incorrect points. The biggest incorrect point you made was about 5 ghz. 5ghz is far less effective at traveling through a medium than 2.4ghz. As you stated, 2.4ghz has a much farther range per watt. Therefore, you would need a much more powerful signal at 5ghz than at 2.4ghz to penetrate a brick wall. You are correct about interference and the Frenzel zone. Don’t want to break it unless you have to.
      No disrespect to your grandfather, but they didn’t even have the tools available to effectively use the VHF range. They were down in the 146mhz range.

    2. Sopar

      The trick to using this product is to find the spot where your reotur’s signal is at about 50%,as it will only repeat as good of a signal as it can receive. I used a free program called inSSIDer and my laptop to find that spot, and then to ensure that the repeated signal was strong enough at the spot where I was trying to get good signal. You can see the graph from inSSIDer of the end result in the gallery. Now, instead having a fair signal barely good enough for YouTube, I can now watch Hulu in HD!


Leave a Reply

Your email address will not be published. Required fields are marked *