Larger WLAN antenna not boosting signal - why?

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Madcap

Weaksauce
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Mar 2, 2008
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Hey all, I bought a larger WLAN antenna for my router but the signal is not improved. I'd appreciate an explanation, or even better suggestions on how to improve the signal.

I have a Zyxel P-2812HNU-F3 wireless router which looks like this:
http://www.telenor.no/privat/kundeservice/bredbandshjelp/zyxel_p2812/ . I use a pretty standard WPA2 2.4 Ghz setup, and there are few other wireless networks broadcasting in the area (perhaps 1-2).

I won't comment on Zyxel's naming schemes except to say there are apparently several similarly named models. The manual for a similar device without external antennas can be found here:ftp://ftp.zyxel.com/P-2812HNU-F3/user_guide/P-2812HNU-F3_1.0.pdf , I couldn't find the manual for my exact model.

I recently replaced one of the antennas you can see on the picture in the first link with the following antenna (directly on the router, without using the included cable):

http://www.konigelectronic.com/nl_nl/1116940

However, this didn't improve the signal. When I tried the larger antenna alone (without the remaining small antenna), the signal actually got worse. I suspect there is something I haven't understood here.

Thanks for any help!
 
So many factors impact WiFi signal strength. Distance, building conditions such as wall composition, electrical, other networks, etc.

Can you give us some background on the situation that led to purchasing the antenna?

Aside from that I can say you should see what channels the other networks are running on and make sure you are using a different one. Keep in mind that you should use only 1,6, or 11.
 
The Wi-Fi signal in the floor above and below are rather weak and sometimes lead to disconnects. I hoped that getting a larger antenna would solve the problem.

I don't have the opportunity to check the status on the other wireless networks right now, but I don't think interference from them is a problem as they are relatively far away.

Too bad I don't have the manual for my exact model as there might be some useful information there. Maybe the transmitter in the router is too weak to handle a large antenna (like a moped engine in a car)? Do the two antennas have to be identical?
 
I would try reorienting the antennas and/or moving the router. If your model supports DD-WRT or Tomato firmware they often support increasing the transmitter power.
 
I would suggest looking at the Antenna patterns that are given off. Most patterns will change depending on orientation.
 
Yeah like k1pp3r is saying, look up the radiation pattern for the antenna and adjust the orientation so you have more power radiating to your areas with poor coverage.

Ignore the suggestion to increase your transmit power as that usually just overloads the radio and increases your noise floor making things worse. Even if the router's radio can handle it that just means that the mobile devices will hear the router better, but the router still won't be able to hear the mobile devices as you can't increase their transmit power.
 
The std 2-3db omni-directional antennas have a fairly spherical radiation pattern. A 270 degree sphere with the hole in the opposite direction than the endpoint of the antenna.

Omni-directional antennas signal flattens out in a donut like hortizonal shaped radiation pattern as the db gain is increased.

A 9db omni-directional antenna like you purchased typically makes a donut shaped radiation pattern with zero signal straight up and straight down and a outward reaching radiation pattern in the horizonal plane compared to the direction of the tip of the antenna.

Also that wireless access point uses MIMO or multiple in multiple out signaling, having two different radiation patterns is going to make the internal algorithms freak out as the phase variance of the signal is going to be farther away from the norm.


Wireless requires both a client and a reciever to be able to talk to one another. Just because you increase the signal to the client (and you see a stronger signal) does not mean that your client can transmit a stronger signal back. This occurs when you see a strong signal and you still seem unable to achieve any improvement in throughout.

So.... start with buying 1 of these: http://www.newegg.com/Product/Produ...U6744&ef_id=UWYzRgAABKuF@Fzx:20140510035632:s

and tilting your antennas at a 45 degree axis. You may have to figure out which way you need to rotate the flat axis on the antennas as well, but I would rotate them so that each is opposite of the other. That way you have 100% equal polorization in both planes. This setup isn't going to give you the best distance horizonally but will give you someone that is similar to what your old antennas gave you without the hole and overall a slight performance advantage. Something along the lines of +10% over the factory setup.

Also please read this: http://www.smallnetbuilder.com/wire...516-why-high-power-routers-dont-improve-range
 
Besides being an IT and Gaming geek ... I am also a licensed Ham Radio Operator.

I think you should research how to make a YAGI or LOG PERIODIC antenna with reflectors and directors cut to the appropriate length as well as test for Standing Wave Ratio then match said antenna to proper coaxial connections and adapters for your wireless access point.

After all Wifi is RADIO and I am an enthusiast amateur radio operator and have built my own antennas that range from 1.8mhz HF - 29mhz HF to 144mhz to 220 and 440mhz in addition to experimenting with UHF antennas cut to the 12cm band (wavelength).

basically you need to make an antenna or purchase one that is not a cheap "Hi GAIN" bullshit marketed junk shit antenna from most computer stores.

I have been able to beam a 500mw 2.4ghz signal 3 miles and still maintain a few mbps with home made yagi antennas for 12cm wavelength aka 2.4 ghz. 5ghz will be 6 cm wavelength and a very small antenna. Read .... http://0x7.ch/text/yagi.pdf

or

watch ... https://www.youtube.com/watch?v=FowqX_xysno

The comments on the youtube channel are people from the peanut gallery, almost all of them are uselessly useless in their lack of antenna tech as well as understanding wavelength generation and propagation.
 
tangoseal said:
Besides being an IT and Gaming geek ... I am also a licensed Ham Radio Operator.

I think you should research how to make a YAGI or LOG PERIODIC antenna with reflectors and directors cut to the appropriate length as well as test for Standing Wave Ratio then match said antenna to proper coaxial connections and adapters for your wireless access point.

After all Wifi is RADIO and I am an enthusiast amateur radio operator and have built my own antennas that range from 1.8mhz HF - 29mhz HF to 144mhz to 220 and 440mhz in addition to experimenting with UHF antennas cut to the 12cm band (wavelength).

basically you need to make an antenna or purchase one that is not a cheap "Hi GAIN" bullshit marketed junk shit antenna from most computer stores.

I have been able to beam a 500mw 2.4ghz signal 3 miles and still maintain a few mbps with home made yagi antennas for 12cm wavelength aka 2.4 ghz. 5ghz will be 6 cm wavelength and a very small antenna. Read .... http://0x7.ch/text/yagi.pdf

or

watch ... https://www.youtube.com/watch?v=FowqX_xysno

The comments on the youtube channel are people from the peanut gallery, almost all of them are uselessly useless in their lack of antenna tech as well as understanding wavelength generation and propagation.
Click to expand...

All good and true....

But speeds over 54Mbps will tank as MIMO won't tolerate the changes in SWR, phasing and lack of phase shifted reflections..... Unless you're building a matched set with a reasonable SWR and the other end has the ability to transmit back.

FYI... I was raised in a REACT family where everyone had a HAM license. Mine has been long expired.

You'd love this: http://trevormarshall.com/waveguides.htm

Before Ubiquiti was popular I did a setup for some missionaries in Uganda using a pair of these, laid down horrizonally, and some WRT54Gs setup as a bridge network. Not bad for Approx 10 kilometer wireless link. We had a fairly stable 12Mbps link.
 
Thanks for all the feedback guys, it will take some time to read and comprehend it all! My conclusion so far is of course that this wasn't as easy as i had hoped.

I will try to adjust the orientation of the antenna a bit, but I don't think I'll be making any more purchases until I have an idea of the degree of signal improvement that can be had. I could send an e-mail to Telenor (DSL provider) or Zyxel and ask.

A more expensive option is to get a new router, I haven't read up on those yet so I wouldn't know what to expect compared to what I have now.
 
You should have determined which antenna on the router actually makes a difference. I have a "mimo" router which has 3 antennas. Having the better omni on one made no difference, one made it worse, and one made it better.

Also, you need to phase match if you have actual mimo. Good luck with that.
 
If you're trying to cover multiple floors, stop buying antennas and start buying APs.

Another thing to consider is that in older homes you're looking at 10" or so of solid wood between floors. Getting any kind of signal to go through that is difficult.
 
wizdum said:
If you're trying to cover multiple floors, stop buying antennas and start buying APs.

Another thing to consider is that in older homes you're looking at 10" or so of solid wood between floors. Getting any kind of signal to go through that is difficult.
Click to expand...

This! Having multiple APs with layer 3 roaming is even better. Cisco Meraki does it and doers it easy. I recommend those. You can do it with an MX appliance or a VM concentrator.
 
remixedcat said:
This! Having multiple APs with layer 3 roaming is even better. Cisco Meraki does it and doers it easy. I recommend those. You can do it with an MX appliance or a VM concentrator.
Click to expand...

Not sure if anyone else has had this experience, but we just had to switch from Meraki to Ubiquiti at my workplace. We had 3 Meraki APs at a site, not sure the model, but they ran about $600 each. This gave us about 60% coverage. 3 Ubiquiti UniFi LRs mounted in the same location gave us 100% coverage. We were happy with the Meraki's performance on everything except range though. A lot of our users have circa 2007 MacBooks, which have notoriously bad WiFi antennas, so that was probably a factor as well.
 
Agreed: Ubiquiti Unifi at their price point are a stupid good value.

I have one of the Unifi AC models which is not quite as good of a value...but assuming they every get it fully enabled....that may change.
 
Hmm I had excellent range with the MX60W that I tested.... Did you configure those to use a non-congested channel??? What were the specs of the environment?
 
Guys this is seriously off topic and the OP already stated he has the information he was looking for.
 
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