WRt32x Antenna question: Antenna Gain

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weaklinks
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Joined: 06 Oct 2019
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PostPosted: Fri May 01, 2020 11:57    Post subject: WRt32x Antenna question: Antenna Gain Reply with quote
Hello,

I purchased from Amazon TECHTOO 9dBi Omni WiFi Antenna with RP-SMA Connector for Wireless Network. Should I leave the antenna gain section alone or do I need to make adjustments I know the transmit power we cannot change because FCC. How about the Antenna Gain that has default 0 in it. Also if anyone has the best settings for Wirless to optimize. thank youu
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SurprisedItWorks
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PostPosted: Sat May 02, 2020 19:23    Post subject: Re: WRt32x Attena question Antenna Gain Reply with quote
weaklinks wrote:
Hello,

I purchased from Amazon TECHTOO 9dBi Omni WiFi Antenna with RP-SMA Connector for Wireless Network. Should I leave the antenna gain section alone or do I need to make adjustments I know the transmit power we cannot change because FCC. How about the Antenna Gain that has default 0 in it. Also if anyone has the best settings for Wirless to optimize. thank youu

For the last dozen or so years, most of my professional life has been as an antenna engineer, so I'll take a stab at this one. I can't actually imagine why dd-wrt has a setting for this. It's a matter of antenna design. Nothing dd-wrt can really do about it. (Or is there something going on here that is seriously nonobvious. Anyone?)

BTW, an antenna is not an amplifier, so it cannot produce more transmit power. All it can do is redistribute the power given to it by the transmitter across the sphere of possible directions of radiation. The "i" in "dBi" is for "isotropic." An isotropic antenna is hypothetical thing that distributes the power uniformly across all those directions, and an antenna with 9 dBi gain is producing, in some direction or directions of interest, a power density 9 dB above what an isotropic antenna would produce. That's a power ratio of roughly 8:1. The simplest (not terribly realistic, but if we want simple) model of what's happening is that power is being radiated at equal levels across 1/8 of the sphere and not radiated at all across the other 7/8. So imagine a sphere with the top and bottom chopped off so that only 1/8 of the original surface remains, now in a sort of donut shape. That's your omni pattern.

The takeaway is that you get your gain in one direction by not radiating it somewhere else. In this case, if everything is on one floor of the house, things may be great. If a client is upstairs two levels above the router, it may not fall into the donut and so may receive a significantly lower power level (not actually zero, as real antennas don't go from all to nothing in an abrupt way). So if you need decent coverage in lots of directions that include directions significantly upward and downward, be careful about going with a high-gain antenna. High gain in one direction means low gain (negative number of dBi) in another direction, and a really high-gain omni antenna has a really flat donut. It's not friendly towards clients up or down from the horizontal plane (assuming the antenna is oriented vertically).

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Five Linksys WRT1900ACSv2's on 42926, 44048
VLANs, multiple VAPs, NAS, client-mode travel router, OpenVPN client/PBR (AirVPN), wireguard/PBR (AzireVPN), two DNSCrypt servers (incl Quad9) routed through OpenVPN.
blkt
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Joined: 20 Jan 2019
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PostPosted: Sat May 02, 2020 20:43    Post subject: Reply with quote
I always leave antenna gain at 0, but I assume it's available to input antenna dBi and lower your transmit power accordingly.

SurprisedItWorks is very correct. Here is a duckduckgo image search result for the visual learners out there.



Be careful not to push the signal coverage out and away from you.
scar1943
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Joined: 10 Nov 2018
Posts: 325
Location: South Carolina

PostPosted: Sat May 02, 2020 23:31    Post subject: Large gain router antenna Reply with quote
Folks, I think the answers above are spot on technically, theory seems sound. I personally have been a licensed ham radio operator since the 70s, so I'm not a stranger to antenna structures and theory, but in no way an “expert”. I can post my personal experience taking the stock router antennas, and replacing them with the larger (taller) higher gain models. Leaving the router where it was (in my case), noticed no “notable” signal change or range increase. As always, your personal mileage may vary. But I have serious reservations, that you will see a performance increase worth of the cost of the larger antennas.
Per Yngve Berg
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PostPosted: Sun May 03, 2020 12:13    Post subject: Reply with quote
Entering a value in antenna gain will only lower the transmitted power.
SurprisedItWorks
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Joined: 04 Aug 2018
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Location: Appalachian mountains, USA

PostPosted: Sun May 03, 2020 12:30    Post subject: Reply with quote
Per Yngve Berg wrote:
Entering a value in antenna gain will only lower the transmitted power.

So there you have it, folks. It's a regulatory thing. Law limits the radiated power, so entering a gain figure matching that of the actual antenna(s) corresponds not to increasing power to clients in the favored directions but to decreasing power to clients in the nonfavored directions. If you instead leave the antenna-gain setting at 0 dBi while using a higher-gain antenna, you'll be doing a little of both, but unless you've set Tx power below the legal limit, you'll be doing it illegally. (Thanks, Per.)

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Five Linksys WRT1900ACSv2's on 42926, 44048
VLANs, multiple VAPs, NAS, client-mode travel router, OpenVPN client/PBR (AirVPN), wireguard/PBR (AzireVPN), two DNSCrypt servers (incl Quad9) routed through OpenVPN.
weaklinks
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Joined: 06 Oct 2019
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PostPosted: Wed May 06, 2020 1:29    Post subject: Reply with quote
thanks guys way over my head. but thank you for all the deailed information.
kernel-panic69
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PostPosted: Wed May 06, 2020 2:13    Post subject: Reply with quote
I think the strongest antennas you can get anymore through any vendor is 20 or 21db gain, if I am not mistaken. The mesh-dish directional antennas used around 20 years ago for the ~1 mile and ~6.2 mile links some folks I know set up were 24db gain, and I think the hardware was Orinoco. I just don't remember if it was Linux 2.2 or 2.4... I've slept since then Wink

Pacwireless made these, they are now defunct, and the company that took over, Laird, no longer makes these AFAIK, but this is basically what they used:


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weaklinks
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PostPosted: Wed May 06, 2020 10:34    Post subject: Reply with quote
holy cow my home is small and I just have one small problem.

My bedroom on the footboard of the bed I got signal and by the headboard i don't the TV is to the left and EcoDot honestly I a missing what 5 feet, are there settings that I can adjust?
kernel-panic69
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PostPosted: Wed May 06, 2020 13:37    Post subject: Reply with quote
Well, referencing the stickies at the top of the forum here: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=311117


https://www.dd-wrt.com/wiki/index.php/Atheros/ath_wireless_settings

https://www.dd-wrt.com/wiki/index.php/Advanced_wireless_settings

.... maybe some others will point out specific settings.

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blkt
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PostPosted: Thu May 07, 2020 4:12    Post subject: Reply with quote
Wireless Network Mode: NG-Mixed (or Mixed if you want slow B rates)

Wireless Channel: 1 (or 6, or 11, Never Auto)

TurboQAM (QAM256): Disable

Short Preamble: Enable

Single User Beamforming: Probably Disable

Multi User Beamforming: Absolutely Disable

Beacon Interval: 101

DTIM Interval: 2

Sensitivity Range (ACK Timing): At Least 900

I have no idea what your 5 GHz settings are, but follow similar principles (AC/N-Mixed 36-48 149-161).

For wireless security tab, only check WPA2 Personal and CCMP-128 (AES).

Save on each page as you make changes. Done? Reboot.

You will very likely want to go back to OEM Linksys WRT32X antennas positioned straight up. Turn off the router when doing this.
weaklinks
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Joined: 06 Oct 2019
Posts: 37

PostPosted: Thu May 07, 2020 10:04    Post subject: Reply with quote
Thank you i have done what you suggestion. I will let you know the outcome thank you again
weaklinks
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Joined: 06 Oct 2019
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PostPosted: Thu May 14, 2020 2:29    Post subject: Reply with quote
weaklinks wrote:
Thank you i have done what you suggestion. I will let you know the outcome thank you again


Hello,
Quick update since the change, as far as 5g the settings you requested are doing really well, I am able to have decent speeds in my bed room. The 2.4 has been having issues. when i try to even do a speed test it takes a long time to start and my speeds are sooo bad when they do.
WRT32X
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Joined: 02 Apr 2020
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PostPosted: Thu May 14, 2020 16:25    Post subject: Reply with quote
I didn't know these settings.. must these setting also be set on the 5Ghz AP?
And can channel width best set to 20 or 40?

blkt wrote:
Wireless Network Mode: NG-Mixed (or Mixed if you want slow B rates)

Wireless Channel: 1 (or 6, or 11, Never Auto)

TurboQAM (QAM256): Disable

Short Preamble: Enable

Single User Beamforming: Probably Disable

Multi User Beamforming: Absolutely Disable

Beacon Interval: 101

DTIM Interval: 2

Sensitivity Range (ACK Timing): At Least 900


Last edited by WRT32X on Thu May 14, 2020 16:57; edited 3 times in total
SurprisedItWorks
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Posts: 927
Location: Appalachian mountains, USA

PostPosted: Thu May 14, 2020 16:49    Post subject: Reply with quote
Some of those settings, like TurboQAM and NG-Mixed, are specific to 2.4G wifi.
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Five Linksys WRT1900ACSv2's on 42926, 44048
VLANs, multiple VAPs, NAS, client-mode travel router, OpenVPN client/PBR (AirVPN), wireguard/PBR (AzireVPN), two DNSCrypt servers (incl Quad9) routed through OpenVPN.
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