antenna waste of money?

antenna waste of money?

Iv had problems connecting from a linksys wireless G model WRT54G to wireless on the 2d floor. I am told extra thick walls prevent it,hence I don't want to waste money buying linksys HGA7S antennas if it wont create coverage on the second floor.

ideas? comments?

Reply to
Joe
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Well the answer is a definite "maybe" Buy them at a retail store and keep the receipt for a return if necessary. I have used those antennas at my house to improve a marginal connection from a 2nd floor WAP11 to the first floor (plaster walls, wood floors). However, at my friend's house the antennas didn't help much (going through brick walls to exterior patio) and she was much happier when I replaced her WAP11 + HGA7S combo with a new Linksys SRX model. (her reception improved even though she still uses the standard built in Dell 802.11g card -- a pre-N "SRX" card was not necessary)

-- Paul

Reply to
Paul

Well....maybe. Sometimes it will help, sometimes it wont. Depends on the compistion of the structure

I would recommend, if you can, run an ethernet cable up to the second floor from the router ethernet ports on the router on the 1st floor. Get a second router/Access point and plug in the ethernet cable from the router downstairs into the second router's internet entry point. There, now you have coverage on the 1st and second floors

Reply to
KH

You may need to position the existing antennas horizontally. Also take a piece of A5 card fold it at 60 deg, cover it in silver foil and place it behind and around the antennas, works great for me. Regards, Marin

Reply to
Martin²

High gain omni antennas will do nothing for 2nd floor coverage. Let's pretend you don't have "extra thick walls". Antennas do not create additional RF. They redirect the RF available from the xmitter and send it in various directions and patterns as defined by the antenna construction. The stock low gain 2dBi Linksys antenna pattern looks like a donut or torus, with the antenna through the hole in the donut. I higher gain version of this omni antenna is a flatter and larger diameter donut. (The volume of the donut is constant). You get more gain at the edge of the donut (perpendicular to the antenna), but you loose gain in the upwards and downwards directions. In other words, the exact opposite of what you're trying to accomplish.

You can tilt the antenna to a horizontal position, and get much better up and down coverage, but at the expense of horizontal coverage. A good compromise is two high gain antennas, one vertical and one horizontal. The catch is that you lose some of the benifits of diversity reception.

Ideally, what you want is a single directional antenna (patch, panel, dish, coffee can, whatever) pointed upstairs, and the other port with a stock omni antenna. However, that ignores the "extra thick walls" problem. What you'll probably see is an ability to connect, but not be able to stay connected. That's what signals that bounce around do. You can probably make this work with a laptop that can be moved around, but I don't think you want to be moving a desktop every time someone moves something in the RF path. If the connection is not reliable, it's not useable.

I suggest you run a CAT5 cable or use some other method of bridging the downstairs and upstairs. HomePNA (phone line networking), telco cable, power line networking, coax cable, or just run CAT5.

Reply to
Jeff Liebermann

Jeff, I'm curious about how this works. (2 antennas, 1 pointed up, 1 pointed horizontal) When the computer on the same level "talks to" the WRT54G does the antenna pointed up tend to receive the signal? And when the computer on a different level "talks to" the WRT54G does the antenna pointed horizontal tend to receive the signal? I think that is what you are saying. But what happens when the WRT54G talks back to the computers. Which antenna will it use? Is it smart enough to use the correct antenna at that moment? And would this smartness vary if there was traffic from both computers at the same time?

Reply to
DanR

It works fairly well.

Yes. You used the right words with "tend to". There's no guarantee that it will be the preferred antenna. The way diversity reception works is that the preferred antenna is one that *LAST* received a non-corrupted packet. If data corruption becomes excessive, then the receiver starts scanning for a better antenna. It's not instantaneous and may take a while for the access point to start scanning.

Probably. Again, no guarantee. With the main lobe of the antenna pattern for a horizontal omni being up and down, it's most likely that the horizontal antenna will pickup the upstairs signal first (or better). Remember, there's little or no RF interaction between the two antennas.

Which ever antenna it heard the last non-corrupted packet. There's no diversity on transmit. It simply uses the antenna that was selected for receive. However, there are some really old access points that would do diversity receive, but would only transmit on one antenna. I'll have to dig through my mess of notes to find the makes and models.

No, it's not very smart. If the "wrong" antenna is initially selected, it will take a succession of corrupted packets to convince the access point that it's time to try the other antenna. If the signal is sufficiently marginal to be useful, it may never try to switch until the signal is totally lost. This is not as horrible as it may sound because the utility is not for getting the best range or performance. Instead, it's for dealing with the all too common multipath and reflections found in indoor environments. Reflections are delays in the signals which can land in between packets. Instant data corruption. Chances are good that the other antenna will NOT be in the area affected by the same reflections. So, if the data gets trashed, it tries another antenna. Not great, but better than one antenna.

Nope. Diversity antenna selection is by the MAC address, which is by the connection. I wish there was a table easily available for which antenna is selected for which client radio. However, all that is done transparently in the RF chipset and does not involve anything in the MAC controller. Therefore, not data is available.

Where problems start is if you do something tricky like two independent antennas and two clients talking to each other. The access point has to switch between antennas for every packet. All modern chipsets handle this with ease, but older incantations had problems. If the traffic is going through the access point, and each client is on a different antenna, it can slow things down tremendously with these old access point chipsets.

Reply to
Jeff Liebermann

Thanks Jeff for all the info.

Reply to
DanR

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