My first antenna mod WRT320N and performance

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dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Mon Nov 15, 2010 23:38    Post subject: My first antenna mod WRT320N and performance Reply with quote
Hi there,

First post here. Would welcome inputs/suggestions.

I got a new WRT320N, also an antenna mod kit that came with two 7dBi antennas and U.FL to RP-SMA Female Pigtail adapters from an eBay seller (see item 350405887291).


I have the following setup:


WRT320N Router Setup:
Firmware: DD-WRT v24-sp2 (08/07/10) mega
Wireless: 5GHz-only, 40MHz band width
Channel : Auto
Tx Power: 71mW (default)

All other settings default.

Location: inside a room 5 feet above ground on top of desk hutch. Wall between router and hallway.

Wired:
Located in same room as router. Dell Core-Duo PC w/ 3GB memory. Windows 7 32-bit. Gigabit ethernet (Cat 5e cable to the router). Test file in 2TB internal SATA2 HDD.


Wireless:
Dell P4 2.8GHz w/ hyperthreading. 1.5GB memory. Windows 7 32-bit.
Linksys WUSB600N Dual-Band USB adapter connected to PC via USB hub.
Encryption: WPA2-AES
Test file: in internal SATA HDD.

Distance of the two PC's:
About 23 feet with a hallway in between the two rooms where the PC's were located (doors of 2 rooms opened).


The Mod:
So I followed the instructions from the eBay seller and drilled a hole @ the back of the WRT320N for one external antenna first.


According to the seller, the #1 antenna port is 2.4GHz (Tx/Rx), #2 antenna port is Rx only (freq?), #3 antenna port is 5GHz (Tx/Rx).


Since I was using N/5GHz-only, I connected the first external antenna to antenna #3 port.

Performance:

1. No mod:
Wireless link speed was around 162Mbps as reported by Windows 7.
Transfer speed: 54Mbps (from router system info/wireless).

2. With external 7dBi antenna connected to internal antenna port #3
Transfer speed: 60Mbps (10% increase)

3. 2nd mod
Antenna port #1 is said to be for 2.4GHz (see the eBay item description). However I noticed if I removed the U.FL connection, the throughput dropped. So it seemed port #1 also affected 5GHz performance.


I noticed for 5GHz band the signal pickup was very sensitive to the location of the antenna. Because the location of the room where the other pc was located was to the left of the router, I tried switch to use the internal PITA intenna on the left side for antenna port #1 instead. I left the internal PITA antenna for port# 1 (located on the right) unused.

With this setup, I noticed another 5% increase of transfer speed(63Mbps).

4. Use of 2nd external antenna
I tried connecting the 2nd external antenna to antenna port #1 w/o drilling a 2nd hole to the back of the router. This gave another 5% gain of transfer speed(to 66Mbps).


Additional notes:
I tried connecting one external antenna to Rx-only antenna port #2 (the middle port) and then try downloading a test file from PC #2 onto PC#1. It didn't help with the Rx speed.


Conclusion:
Gain of using the 7dBi antenna mod kit: 15-20% increase of transfer speed (from 53Mbps to 66Mbps).


My thoughts:
I expected WRT320N to provide a better wireless throughput. With the 7dBi antenna mod kit, I got only moderate increase of performance.

Questions:
1. Are the external antennas 7dBi gain antennas? Or really only 3dBi gain antennas perhaps? The little gain caused me to be skeptical.

http://reviews.ebay.com/About-the-High-Gain-Antenna-for-wireless_W0QQugidZ10000000003573572


2. Any suggestions to further increase the wireless throughput? I really want to get it to be close to 100Mbps.
Sponsor
blikjebier
DD-WRT Novice


Joined: 02 Oct 2009
Posts: 22
Location: The Netherlands

PostPosted: Tue Nov 16, 2010 12:02    Post subject: Reply with quote
Hi dkk991m,

First of all you need two external antenna's to gain extra performance. Second you wan't to use the a band, but you are currently using the wrong antenna's (b band).

If you wan't to gain extra performance you could take a look on ebay for a 5 GHz antenna:

http://cgi.ebay.com/High-Frequency-5GHz-7dBi-SMA-Antenna-802-11N-Support-/120645107306?pt=LH_DefaultDomain_0&hash=item1c17023e6a#ht_3104wt_1139

Can you measure extra performance on the b band(2,4GHz) with the external antenna kit?

_________________
Linksys: WRT320N v1 converted to E2000
OC: 400,200
DD-WRT: Brainslayer build: dd-wrt.v24-15704_NEWD-2_K2.6_mega-e2k-e3k
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Tue Nov 16, 2010 21:53    Post subject: Reply with quote
Hi blikjebier, I actually did a test on 5GHz/2 ext antennas, which yielded speed of 66Mbps (see pt #4).

About the antennas, I did read the thread here:

http://www.dd-wrt.com/phpBB2/viewtopic.php?t=82313&highlight=band

However, I was told by the ebay seller the antennas would *also* work with A band (5.4GHz).

So looks like the information I got from the seller was not true?


I switched to B band (2.4GHz) anyway. The results were a bit more disappointing.


Wireless settings:
N(2.4GHz only)
Channel width: 20MHz
(it was quite crowded and hard to use wide channel)
Tx Power: 71mW (default)
Encryption: WPA2/AES

With A band (5GHz), signal quality was about 21-24.
With B band (2.4GHz), signal quality was 35-40, which seemed better compared to 5GHz.

Link Speed (2.4GHz): 104Mbps


Here are the performance figures (transfer speed - from WRT320N admin):


Reference: no antenna connected to antenna Tx/Rx ports 1& 3: 28Mbps

1. internal antennas (no mod): 61-62Mbps
2. 1 antenna only (extenal antenna connected to antenna port 3 only): 55Mbps
3. 2 external antennas (added 2nd external antenna to antenna port 1): 50Mbps
4. 1 ext antenna to port 3, internal antenna 3 connected to port 1: 57Mbps


I can categorize the wireless location to be same as location B like in this setup (although only 23 feet instead of 45 feet):

http://www.smallnetbuilder.com/wireless/wireless-howto/30488-how-we-test-wireless-products-six-location-open-air-method


So for B band (2.4GHz), no mod actually yielded the best result (the difference was about 20% higher compared to 2 ext antennas). Should I suggest folks not to get this antenna mod kit for 2.4GHz?


This is just one set of test result. My house is close to the street and the 2.4GHz band is somewhat crowded (quite several neighbors in this band--although I selected the one that had least interference from others with similar signal strength).


I'm no antenna expert here, but I'm seeing in my antenna tests 5GHz results were better than the 2.4GHz results.

In any case, the figures for both bands do reveal something. The external antennas aren't helping in any significant way as I hoped for in my case (if they do help). Perhaps they are just 2-3dBi antennas. And they only show some improvements--only in 5GHz--in my case.


blikjebier is there an improvement with the antennas you ordered from the other ebay seller -- and how much (transfer speed)?

Perhaps I should get that other external antenna you pointed to on eBay and get some newer results to compare with this 2 antenna mod kit.

Perhaps others can confirm with their own performance figures (transfer speed comparison)?


Last edited by dkk991m on Wed Nov 17, 2010 1:33; edited 1 time in total
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Tue Nov 16, 2010 23:11    Post subject: Reply with quote
As another test, I pulled out my good old DLink DI-524 G router's 2dBi external antenna, hooked up to the WRT320N, and compared to the 2.4GHz no-mod setup.

The single 2dBi DLink antenna alone yielded about 6-10% increase in transfer speed (3-5Mbps higher) compared to no-mod speed.


So it looks like the 7dBi antenna mod kit I received was more for 5GHz, and the real gain was probably around 2dBi from each antenna (or slightly less--depending on if you get a good one or not). The gain in 2.4GHz would perhaps be like 1dBi... in my case (my guess).


I think if we can locate a pair of real (not fake) 5dBi antennas, we can get up to 30-40% increase (2x2x10%) in throughput, perhaps?


I looked around, there simply aren't many moderate/high-gain (>2dBi) 5GHz/dual-band omni-directional antennas for < $15 on the market now (if anyone finds one let me know). I doubt the generic eBay antennas are any high-gain antennas at all.


Last edited by dkk991m on Wed Nov 17, 2010 6:30; edited 1 time in total
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Wed Nov 17, 2010 6:29    Post subject: Reply with quote
I found a TRENDnet Dual-Band 11a/g 7/5dBi Indoor Omni Directional Antenna:

http://www.amazon.com/TRENDnet-Dual-Band-Directional-Mounting-TEW-AI75OB/dp/B000ERCNZY

Since 802.11a operates in similar range as 5GHz 802.11n, I hooked up this external antenna to the back of one of the WRT320N's external antenna port I put in.

This time the throughput went up to 74Mbps--sweet!

This was with just one 7dBi external antenna + one generic (2dBi I'd say) antenna. With two 7dBi external antennas, I'd imagine the throughput will go up to 80+Mbps.

So the key is to find some of these real 5GHz-capable 7dBi external antennas.


PS: I also tried the DLink ANT24-0700 external antenna--didn't help the slightest in 5GHz band. I did not try 2.4GHz band as that's not what I'd be using for.
blikjebier
DD-WRT Novice


Joined: 02 Oct 2009
Posts: 22
Location: The Netherlands

PostPosted: Wed Nov 17, 2010 16:16    Post subject: Reply with quote
Do you have an ad of the antenna kit you purchased from the internet? The kit I saw on ebay didn't mention a or b band.

I have ordered two b band antenna's and one a band.
Since my wireless printer and iPhone don't support the a band i'm only going to installe the b band antenna's. When my own mod is delivered and ready I will posts the test results in this topic.

_________________
Linksys: WRT320N v1 converted to E2000
OC: 400,200
DD-WRT: Brainslayer build: dd-wrt.v24-15704_NEWD-2_K2.6_mega-e2k-e3k
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Wed Nov 17, 2010 19:22    Post subject: Reply with quote
Check out ebay item #350405887291. I think it's the same kit several other folks here bought also.

The item description doesn't mention the kind of antennas (a or b band). I got a reply from the seller after I asked about the item. The set I got was more for 5GHz I believe based on my own test results (see previous performance figures)--although my tests were very rough estimates... .


blikjebier, what's the throughput you get out of your WRT320N now on 5GHz band with the antennas you have --did you get a set from the same ebay seller above?


Just for the sake of comparison, I went to a store and grabbed a LinkSys Dual Band WMP600N PCI adapter, and plugged in those two 2dBi (according to LinkSys spec) rubber duck antennas into my WRT320N.

I am now getting about 70-72Mbps xfer speed with the Linksys antennas, which is still slightly (10%) higher than the throughput with the ebay antenna mod kit (66Mbps).

So I am now quite convinced the antennas from the ebay mod kit are 2dBi antennas (unless the LinkSys antennas performed higher than the spec).


I do have a separate question--and don't know if any techie out here might know. The xfer speed graph shows really big swings from time to time (see WRT320N xfer speed graph 1).

Anyone knows why this is so? Nothing special is happening in the immediate environment.

I wonder if there is some firmware or hardware (signal) influence in these large swings of speed?

This happened w/ all the antennas I've tried, so it doesn't seem these swings were related to a particular set of antennas.


Last edited by dkk991m on Tue Nov 23, 2010 8:23; edited 1 time in total
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Fri Nov 19, 2010 20:04    Post subject: Reply with quote
dkk991m wrote:
Check out ebay item #350405887291. I think it's the same kit several other folks here bought also.

The item description doesn't mention the kind of antennas (a or b band).

...

The set I got was more for 5GHz I believe based on my own test results (see previous performance figures)--although my tests were very rough estimates... .


To clarify:

The antennas from the ebay mod kit do provide some signal gain in 2.4GHz band, so I cannot really say these are 5GHz-only antennas. They just performed slightly less than the WRT320N's internal PITA antennas in 2.4GHz (in my own tests, again this is rough figure).

Of course, folks who are hoping for a 7dBi gain, or a sizable gain compared to the internal WRT320N's PITA antennas -- would be disappointed.


I repositioned my LinkSys Dual-Band N USB adapter and placed it higher--at same level as the top of the LCD monitor (it was placed on the desk before).

With this repositioning @ 5GHz I can now get about 75-80Mbps at a distance of 23 feet. This is another 15% boost (from 66Mbps) -- and is as good as the 2dBi antenna mod kit... .
blikjebier
DD-WRT Novice


Joined: 02 Oct 2009
Posts: 22
Location: The Netherlands

PostPosted: Mon Nov 22, 2010 11:50    Post subject: Reply with quote
dkk991m wrote:
dkk991m wrote:
Check out ebay item #350405887291. I think it's the same kit several other folks here bought also.

The item description doesn't mention the kind of antennas (a or b band).

...

The set I got was more for 5GHz I believe based on my own test results (see previous performance figures)--although my tests were very rough estimates... .


To clarify:

The antennas from the ebay mod kit do provide some signal gain in 2.4GHz band, so I cannot really say these are 5GHz-only antennas. They just performed slightly less than the WRT320N's internal PITA antennas in 2.4GHz (in my own tests, again this is rough figure).

Of course, folks who are hoping for a 7dBi gain, or a sizable gain compared to the internal WRT320N's PITA antennas -- would be disappointed.


I repositioned my LinkSys Dual-Band N USB adapter and placed it higher--at same level as the top of the LCD monitor (it was placed on the desk before).

With this repositioning @ 5GHz I can now get about 75-80Mbps at a distance of 23 feet. This is another 15% boost (from 66Mbps) -- and is as good as the 2dBi antenna mod kit... .


I think you have 5 GHz antenna's.
My antenna's are still not delivered, so we have to wait for extra test results.

_________________
Linksys: WRT320N v1 converted to E2000
OC: 400,200
DD-WRT: Brainslayer build: dd-wrt.v24-15704_NEWD-2_K2.6_mega-e2k-e3k
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Tue Nov 23, 2010 8:41    Post subject: Reply with quote
blikjebier, I think you're probably right--it's not good enough to be considered a 2.4GHz antenna in my case.

I've now upped the CPU/memory speed to 400/200/100. It gives me another slight help in the thru'put.

I am really getting a good increase in thru'put for placing the Wireless N USB adapter @ the right location (at top of LCD monitor). That alone gives an increase of up to 10Mbps.


With all attempts combined (antenna + wireless USB positioning + CPU speed increase), I am now getting up to around 85Mbps sometimes, compared to 50+Mbps.


I am going to get a heat sink and install it when it arrives to cool down the Broadcom CPU as it is now registering about 181F @400MHz (it was 171F at its default speed).

I am pretty sure the simple reason Cisco didn't put external antennas/heat sink in this product: to lower the cost... .
blikjebier
DD-WRT Novice


Joined: 02 Oct 2009
Posts: 22
Location: The Netherlands

PostPosted: Wed Nov 24, 2010 12:12    Post subject: Reply with quote
dkk991m wrote:
blikjebier, I think you're probably right--it's not good enough to be considered a 2.4GHz antenna in my case.

I've now upped the CPU/memory speed to 400/200/100. It gives me another slight help in the thru'put.

I am really getting a good increase in thru'put for placing the Wireless N USB adapter @ the right location (at top of LCD monitor). That alone gives an increase of up to 10Mbps.


With all attempts combined (antenna + wireless USB positioning + CPU speed increase), I am now getting up to around 85Mbps sometimes, compared to 50+Mbps.


I am going to get a heat sink and install it when it arrives to cool down the Broadcom CPU as it is now registering about 181F @400MHz (it was 171F at its default speed).

I am pretty sure the simple reason Cisco didn't put external antennas/heat sink in this product: to lower the cost... .


I have installed a 23mm x 23mm x 10mm heat sink.
Ordered from this webshop:
http://www.xsfans.com/index.php?main_page=product_info&cPath=36&products_id=285

It fits, but a 21 mm x 21 mm x 5 mm would fit better in the casing.

_________________
Linksys: WRT320N v1 converted to E2000
OC: 400,200
DD-WRT: Brainslayer build: dd-wrt.v24-15704_NEWD-2_K2.6_mega-e2k-e3k
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Wed Nov 24, 2010 21:23    Post subject: Reply with quote
Personally I'd think a larger heatsink dissipates/spreads heat better (assuming all other factors equal). Yours looks pretty good.

I got mine here:

http://cgi.ebay.com/LOT-FOUR-small-copper-HEATSINKS-VGA-RAM-IC-CHIP-/110605002595?pt=LH_DefaultDomain_0&hash=item19c0926763#ht_930wt_924

20x20x6.3mm. It's copper-coated aluminum. Somewhat smaller.

I'm going to bump up the speed to 480/240 once the heat sink arrives.


I've also added four 3/8 inch height self-sticking transparent rubber feet I found @ Target ($3.2 for a pack of eight). It does help dissipate heat @ the bottom somewhat better.

With the four rubber feet the WRT330N looks like a spaceship.

It's amazing so much people need to do to make up for what Cisco (and other vendors) lacks in delivering the performance on these N routers (particularly with all the super-high price tags). We should have charged Cisco for all the hours we've spent on the upgrade we've done. ;-)


BTW, I noticed the Broadcom chip is BCM4717... (see the very first pic of the board).

So I wonder-- the WRT320N I've got has a newer Broadcom version that doesn't have the various bugs (like the reset button)?

But the DD-WRT Admin page still says it's Broadcom "BCM4716 chip rev 1".

So what the DD-WRT Admin page reports is incorrect?
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Sat Dec 11, 2010 1:23    Post subject: Reply with quote
Brief update:

I got the heatsink and installed it. Temperature now measures 135F-140F instead of 180F @ 400MHz CPU speed (with room temperature around 68F-71F). Much improved!

I highly recommend anyone over-clocking the Broadcom chip to get a heatsink--it's definitely worth it.
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Sat Dec 11, 2010 8:51    Post subject: Reply with quote
Over-clocking:

I increased the speed to 480/240/120. The temperature now registers 152F with the heatsink installed--which seems to be ok. However, when operating in 5GHz band, the router reboots by itself soon after I initiate a file transfer over the wireless connection. Happens a couple of times already.

If I am just browsing the web the router's connections run fine for at least a good few hours. Once a wireless file download starts, the router drops all the connections (wireless + wired) within a minute.


I have to reduce the speed--unless I don't do file download over wireless connection. :(

Also, with speed @ 480/240/120 I am not seeing any noticeable file download speed increase (compared to 400/200/100) over the wireless connection while the router works.
dkk991m
DD-WRT Novice


Joined: 14 Nov 2010
Posts: 14

PostPosted: Fri Jan 14, 2011 22:41    Post subject: Reply with quote
Just a quick update:

I've got two 2dBi D-Link 2.4GHz antennas from eBay (see from the pic above). They also work in 5GHz just fine.

Pretty good price for anyone wanting to get a slight boost of signal in the 5GHz band. Better than paying extra for those bulky generic 7dBi antennas on eBay (which probably would only get you 2dBi gain anyway).

Don't expect a 7dBi gain from these 2dBi D-Link antennas. But for a slight improvement (10-15% increase in thru'put in 5GHz band), they are good enough--for the price.
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