I want to start this thread, not Broadcomm specific, but as a way for folks to learn about external antennas, and how they can help in a point to point situation.
Basically, a theoretical antenna transmits all around, and receives all around..
Its a lawn sprinkler.. :)
You only have so much pressure to the sprinkler.. if you focus it in one direction, you have more pressure (in one direction)..
that is a reasonable analogy of gain.
IF you concentrate the effort in one direction, you get a better output, (A longer squirt ... it can also add to the receive signal 'gain' becuase it is focussed. (Concentrated in one direction which also means the receiver is only looking in this direction)
A good antenna works both on transmit, AND receive.
Increasing tx power on the router, ap, device, or whatever - works on transmit, but NOT on receive.. so you may get the signal OUT more, but the input is crippled and not in line with the increased output.
With a good antenna, BOTH the output and input are increased..
For every doubling of tx power in mW, we increase the power by apx 3dB.. for every increase of 3dB, we increase the effective output power in mw by a factor of 2 times the original power.
ie, 20 mW output power, to a 3dBi antenna, = 40 mW effective radiated power (in simplistic terms) , AND if using a good antenna, the receive gain is more or less the same. a weak signal is 'amplified' by the antenna to give a stronger signal to the wifi receiver. (Apx double what we would have without it.
So win win...
Adding tx power, WITHOUT an increase in receive signal strength does not accomplish much.
Power hacks are mostly non productive - apart from causing overheat, non linearity (crappy signal) etc.
Lots of router / AP's have two antenni, they are used in receive mode for selecting the best signal (Diversity - again, in simple terms). IF you use an external antenna, turn this off.. use one antenna (the one with the external added) for tx and rx.. the other is unused.
Diversity can help in situations with reflected signals, as an omidirection antenna has to put up with. but, becuase we are now, presumably, using directional antennas (point to point) not needed.
I hope this is a start, not to resort to which antenna is best.. although it is unrealsitic not to expect some kind of input in that sort. :)
Joined: 30 Nov 2008 Posts: 206 Location: Wherever the wind blows.
Posted: Thu Dec 11, 2008 2:11 Post subject:
Good point JN, thanks for the input.
And to add, if one chooses an external amp with rx amp built in, READ CAREFULLY the input requirements to the amp, ie, the power level, ususally expressed in dBm (Link to calculator on first page of this thread for converting to milliwatts mW)
So, if your new amp wants no more than 15 dBm, you would have to REDUCE the power output of your wrt54g which is set at 70mW (15dBm is apx 30mW.
Failing to do this will possibly damage the amp, WILL lead to overdriving the amp giving a poor quality signal (Errors) and WILL cause interference to other users.
There are legal limits as to the erp (Effective radiated power) for each country, it is worth checking ! . Even adding a high gain rubber duck type antenna may well cause you to break the law in your area. Check and use with care.
Joined: 30 Nov 2008 Posts: 206 Location: Wherever the wind blows.
Posted: Thu Dec 11, 2008 11:08 Post subject:
Thanks Donny (Hows the toe ?)
Great link.
Please add links to any antenna designs you feel are, a. GOOD, and, b. WORK, all appreciated
For any add on external antenni to a non removable antenna unit, I think the best advise is to buy a pigtail connector with the item you want, some firms specialise and make them up for you, buy one with both ends the same (revsma, revtnc or ntype) - ask to have one made -this presumes you have no access to crimpers and no old router to pinch parts from. Cut the pig tail in half, then use these as the connectors.
Because I install LOTS of wifi units for yachties.. I bought a crimper set (Around 40 USD) and the appropriate crimp connectors and cable. RG316 for most internal add ons..
Thanks for the input (again !)
ps, did I ask how your toe is ??
What this thread needs now is a definitive guide to all the advanced wireless settings, in great detail as appertains to an external connector, I have touched on it, but it needs expanding ? any volunteers ?
Joined: 13 Nov 2008 Posts: 5266 Location: CENTRAL Midnowhere
Posted: Thu Dec 11, 2008 14:06 Post subject:
ruddles wrote:
ps, did I ask how your toe is ??
It BURNS...IT BURNS. Oh. Wait. No..that's from the holy water. But the blistering has almost started to go down. _________________ Warning: I'm "out of my element!"
http://www.youtube.com/watch?v=MjYJ7zZ9BRw&NR=1
wow, great thread, donny has not mentioned the peacock once here yet. However I do have a serious question on this subject. I have an old signal booster that I used when I had a wrt54B unit. it was made by linksys, designed to work with the linksys wrt54b unit, I know nothing about electronics but would it also work with my 'G' device signals since the connections are nothing more than inserting to the antenia jacks ? _________________ 1 WRT160N v3 - remote AP WPA2 Personal Aes dd-wrt-mini-trailed CPU OC400,
2 wrt54G v3(BCM4712 chip rev 1, corerev=7)- AP WPA2 Personal Aes dd-wrt-mini-generic CPU OC228,
1 wrt54gs v6 - remote AP WPA2 Personal Aes dd-wrt-micro CPU OC228 ,
3 WAP54g v3 - repeater, client Bridge, repeater bridge dd-wrt-micro CPU OC225,
1 NetGear WNR2000 v3 AP Atheros AR7241 ver 1 rev 1.1 (0x0101) Trailed build CPU OC360
DD-WRT usually the most current BS builds and less frequently lately EKO builds(because of new BS rules that eliminated EKO builds I used).
Joined: 30 Nov 2008 Posts: 206 Location: Wherever the wind blows.
Posted: Thu Dec 11, 2008 21:28 Post subject:
Hiya Gene
answer in 802.11G, is almost certainly NO, unfortunately.
However, it will work at B if you set the router to B only output. For most uses it will still offer a good dl speed. but the b and g specs are differnt for the amp.
Rudds
Patch antennas for pointing at a neighboring antenna through a window. Hangs flat against the glass.
Patch antenna for Velcro-ing to the lid of a laptop.
Yagi for pointing downwind in high-wind areas.
Dish for crosswind in high-wind areas.
Coaxial colinear for homemade high gain omnis.
Slotted waveguide if you have a milling machine you can't find a use for.
General antenna knowledge:
High gain omnis achieve their gain by flattening the radiation pattern. More out = less up and down. You can be standing under a 15 dB gain omni 25 feet up and not see it with a laptop. Point this out to people who whine about cellphone towers in the neighborhood.
Large diameter active elements have a wider low-SWR bandwidth. If you want to make a quality Yagi, use copper pipe, not copper wire.
Directional antennas with similar gain should have similar beamwidth. Yagi, panel, should be very similar.
You have to double the length of a yagi to get double the gain. 15 dB is the practical limit.
this post it very helpful, however i would like clarification on one thing.
using a yagi antenna (the below one)
http://www.hyperlinktech.com/web/hg2415y.php
would i receive any benefit from the built in amplifier found on the Buffalo WHR-HP-G54 as compared to the normal setup found on the Asus WL-500g Premium
Joined: 13 Nov 2008 Posts: 5266 Location: CENTRAL Midnowhere
Posted: Wed Jan 28, 2009 14:00 Post subject:
dustout wrote:
this post it very helpful, however i would like clarification on one thing.
using a yagi antenna (the below one)
http://www.hyperlinktech.com/web/hg2415y.php
would i receive any benefit from the built in amplifier found on the Buffalo WHR-HP-G54 as compared to the normal setup found on the Asus WL-500g Premium
Need to know what you are trying to do....
That being said, you likely don't need an amp.
I have seen some posts that suggest problems (lousy throughput?) with one of the WL500 routers btw. WL520 seems good. _________________ Warning: I'm "out of my element!"
http://www.youtube.com/watch?v=MjYJ7zZ9BRw&NR=1
1) The effects of the amplifier and the antenna would add up at the far end.
2) The antenna would provide a benefit at the amplifier end, but not the amplifier. amplifiers improve outbound signals.
antennas are always the first, best solution to signal strength problems. solve RF problems with antennas to the extent possible, and amplifiers to the extent necessary.
any router will do, the WL500 was on sale ($89 canadian) so that is why i liked it. Also it was white and that will look good on the project. What router would you suggest?
ad5mb wrote:
1) The effects of the amplifier and the antenna would add up at the far end
...
That is called a "Best Practice" in engineering.
so your saying an amplifier will help increase the range when i am sending out a signal, but since the limiting factor in my situation is the free crappy wifi i would receive no gain from it due to it's terrible job of sending me a signal.
However if i were able to add a booster to the free crappy wifi then i would receive added range, because there ability to send me signals would increase.
Yes that makes sense, thank you for clarifying that issue