High gain antennas at both ends?

First, thanks for all the informative posts in this newgroup!

Here's my situation:

I plan to set up a PC on the thrid floor of my house. The cable modem/router is located in the basement, perhaps about four feet underground The distance between it and the upstairs room is about thirty feet horizontal,, thirty feet vertical away. This is a brick house build c. 1940..

The router is a Linksys WRT54GL router v1.1 flashed to DD-WRT .

Using a notebook with a Hawkings HWC54G card (not a Hi-Gain model), I am getting about -45dBm from a position one floor up, and about -72dBm two flights up. The Linksys router antennas were positioned perpendicular to the desired locations. Increasing the transmit power from 28 to 48ma improved the signal just two-three dBm, as indicated by posts in this forum.

While the signal on the third floor is rated poor/bad by the Hawkings ultility, and generally gets just two bars from Windows; the signal is steady, I didn't have any particular delays in getting webpages or downloads, and I got Speedtest scores of about 6mbits/sec, or about

65% of wired speed.

Given that the signal needs to get to a fixed point, it would seem that a directional antenna would be the best answer. Having seen the discussions about transmit power and the need to have both ends transmitting at about the same power for it to do much good, what's the case with antennas? If, for instance, I had a 10dBm directional antenna attached to the router, and a 10 dBm antenna upstairs, would I end up with double the improvement (assuming all was aligned correctly), or would I have just whatever improvement in each direction that came from each antenna?

I guess my real question is: Do these hi-gain antennas improve both transmission and reception, or just transmission?

Assuming that DIY is not an option, what would be good but fairly inexpensive (i.e. not much more than $50) manufactured directional antennas that would be compatible with the Linksys router? Does the use of adapters (i.e.SMA to TNC) hurt performance? If appropriate, I'd also like to know about good antennas for a PCI card and notebook cards that can handle a good antenna, too.

While I may do file transfers down the road, in all likelihood, this connection will be almost entirely for a plain vanilla Internet connection, no video streaming or P2Ping or torrents, big file downloads will probably be as strenuous as it will get. While I'd like to get the signal better, maybe I'm gilding the lily?

Finally, is there anything important I've left out?

Any answers or links would be deeply appreciated. Thanks!

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excuse the ramblings of a clueless lurker but I'd be tempted to try to run a cable between the two rather than the expense and grief of what you are suggesting.

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snipped-for-privacy@yahoo.com hath wroth:

Brick floors? My guess is wood floors and lath and plaster ceilings. The wood is no problem, but the lath and plaster is difficult to penetrate with 2.4GHz RF, especially if the lath has been reworked and reinforced with chicken wire backing.

Unless I missed something, the WRT54GL was only released in the 1.0 hardware version. However, the much much older WRT54G had a v1.1 version (I have one). There's a huge difference inside, especially in amount of RAM, the RF section quality, and the processor clock speed. See table at:

and then check your serial number tag for the correct model number or hardware version.

There's no high-gain model. However, there is a high-power model.

Ok, the math is simple. -45dBmi is a very good strong signal. -72dBm is marginal, but should work at very slow speeds. The difference is

27dB, which you have to make up in either path improvement or antenna gain. A 24dBi gain antenna looks like and is about the size of an outdoor barbeque grill. It will probably do the trick but I don't think you would consider that very practical. It doesn't really matter what style of antenna you select, anything over about 20dBi of gain is going to be big and ugly. You could also distribute the gain between the laptop and the access point with perhaps 13dBi gain at both ends. That would look less obnoxious, but would require fixed positioning of both ends. In other words, the laptop would not be very portable. Similarly, pointing the antenna upwards from the basement would probably all operation only in one part of the house.

Incidentally, your apparently loss through a single floor is: -27dB / 3 = -9dB per floor.

That will help one or two dB. However, you need about 27dB more gain, which is not going to happen by juggling antennas, or even replacing them with relatively small aftermarket antennas.

That's 28 to 48mw (milliwatts). That's an increase of about 3dB, which isn't going to do much for a 27dB shortfall. Increasing just the transmit power only increases the gain in one direction. The other remains the same. If you installed a kilowatt fire belching power sucking amplifier on one end, it still won't work, because you couldn't hear the return signals. When increasing transmit power, it has to be done at BOTH ends of a link to be effective.

Nice. I would have guessed that going through 3 wood or lath and plaster floors would not have worked as well. It appears that you're close and don't really need the full 27dB of gain. Perhaps a few dB would be useful. As a rule of thumb, throughput doubles for every 6dB of gain. The typical 8 to 10dBi patch, panel, or biquad antenna, pointed upwards, should help. It will never give you a -45dBm signal as you were getting at one floor, but it might make it work a bit better.

Maybe. Please note that there are alternatives to wireless, such as running data over the CATV coax, phone line networking, power line networks, and fiber optic links. These are particularly applicable for fixed locations, which seems to be your situation. References on request.

There is no need to have identical gain, type, or configuration antennas on both ends of a link. Antennas are bi-directional and redirect the signal identically in both directions. (Note: antennas do not amplify the signal. They redirect it).

Double, sorta. See my previous back of envelope calculations. If you need 20dB of antenna gain, you can put it all at one end of the link, or you can distribute it in any ratio between each end of the link as long as the total gain is about 20dB. The real issue is antenna size. A single 20dBi gain antenna is rather large. Two 10dBi antennas are much smaller (and cheaper). You could even build your own. Another benfit to distributing the gain is that the beamwidth is wider with lower gain antennas, making aiming and alignment far less critical.

They improve signal in both directions.

Any of the lower gain antennas on this page:

Be sure to look at the physical size of these antennas. The higher gain antennas are probably far too large to be practical.

Adapters are not a problem. Someone did my favorite test of stringing all the adapters he could find together and measuring the loss. See:

The loss was about the same as an equivalent length of coax cable. However, I've seen far too many mechanically crude adapters, that look like they would fall apart without much provocation. If it looks like junk, it probably is and should be avoided.

PCI cards have RP-SMA connectors, which make adding an external antenna easy. The problem is that they usually come with tiny thin RG-316 coax cable, that's quite lossy. The antenna gain makes up for the loss, but the net overall system gain is usually nominal for the typical desktop vertical. I suggest a panel, patch, or biquad antenna pointed at the basement with no more than about 6ft of the tiny coax. Otherwise, go to larger coax, such as LMR-240.

Notebook cards are a problem was many do not have antenna connectors. I don't think your Hawkings card has one. It may be best to either get a PCMCIA card with an external connector:

There are pigtail adapters from this connector to the more common SMA, TNC, or N connectors.

Reply to
Jeff Liebermann

Looks to me like you have a non-problem. I would just use it like it is and wait and see if you really do notice any shortfalls.

And anything you do will probably take you into good reception. I would forget about changing your laptop card and then buying external antenna for it; just improve the router antenna(s) - it's simpler.

You can improve both antennas on the Linksys or just improve one and take the other off.

Although it's do-it-yourself, consider making a couple of reflectors for your linksys antennas. Very easy to do, just print out the images on card-stock, cut-out then glue tin-foil on. They work and should be plenty for your situation.


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Thank you for your comments and suggestions, I plan to use two medium-gain antennas on either end and see what happens.

There is a version 1.1 of the WRT54GL, see

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Hawking Technology does have a line of "Hi-Gain" adapters, see
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Reply to

snipped-for-privacy@yahoo.com hath wroth:

Their "Hi-Gain" is not the same as my idea of "High Gain" which means that that the antenna (or some amplifier) has more gain than usual. In this case, the "Hi-Gain" is just a trade name for a product line and has nothing to do with performance, features, or specifications.

Hi-gain is also an interesting choice of trademark in that it's currently being used by various companies and organizations:

However, checking the trademark, service mark, etc status at:

it was most recently used by: "G & S: Dietary Food Supplement for Pigs" but is now available. It's amazing how old company names and trademarks raise from the dead these days.

Anyway, I don't see an hi, low, medium, or useful antennas on the Hawking page you cited. They're all various wireless clients, with various small antennas attached. There are too many to comment on individually, so I'll leave the selection to you. It's not what I had in mind. Medium gain means (to me) about 10-15dBi gain. High gain is

19-24dBi and is usually a dish or panel. Low gain is 8dBi or less, which is what you typically find on omni antennas and aftermarket antennas. I would consider the Hawking collection as low gain.

Good luck.

Reply to
Jeff Liebermann

I think you are doing pretty well with the router's native antennae, given the building construction.

Yes, the antennas will work on either end. So fixing one on the reception end will improve your performance (though most likely not symetrically).

Also, 10dbi doesn't much count as "high-gain" given the gear available in market these days. It's pretty good improvement compared to the native 2/3/5dbi's that ship with 99.9% of the wifi router products out there.

$50 is a decent budget. Check out the 6.5dbi table-top directional at

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which you should be able to aim straight upward to the area where you need coverage in the 3rd floor.

SMA or TNC connector have both about the same inherent loss/damping.

For PCI cards usually you'd need to go for the R-SMA connector. For the Linksys WRT, they are usually TNC connectors. Make sure to specify these connectors when ordering.

Another option popular in old indoors like brick constructions are boosters (aka amplifiers). The main difference between boosters and antennae is that boosters are active devices, and they actually add extra power to your signal transmission. Antennae on the other hand only shape the wave in a certain fashion (depending on what antenna you choose for the application).

Check out boosters at

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A combo of a 500mW booster and a 6.5dbi table-top directional is also reasonable - it'll really push your performance though.

Note also that gear like boosters or antennae simply give you _stronger_ signal, which doesn't necessarily mean it is higher _quality_ signal. For streaming media apps etc, it's quality that defines the user-experience.

Nothing much I can think of. Some minor areas to keep any eye out would be

# water-pipes: water bodies are generally unfriendly to microwave (which is what wifi is). See article at -

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# Microwave ovens: these cause intermittent signal drop outs when the oven is turned on and it messes up the wave field in the space around it. So if there is an m-oven in the approximate line of connection, you may watch out for it's effects.

Have fun / c24

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I'll repeat. I think you are going overboard to start out. Just improve your router/AP first and take it from there. This will help no matter what you have on the third floor.

Also, to repeat what was already said, antennas work in BOTH directions. For example, my house is 200 meters from the router antenna outside. I had unacceptable reception (-85dB) on the balcony of my house with stock linksys antennas. By putting a cheap 12 dbi antenna (up in the air) on the router end, I now have great reception on the balcony and acceptable reception INSIDE my house using wireless cards with no external antennas.

So, if you won't try a reflector on the router end, then buy an antenna. Here's one on sale, very cheap that should do fine:

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There are other antennas there as well;
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As far as amps go, I think that using amplifier for an inside situation like this where your reception is already functional with

2dbi antennas is way out-of-bounds for this situation. Could even cause problems.


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Try a powerline adapter if you do not want to run a cable

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I agree - you should try just the router/AP side with antenna first. You can always upgrade the client/receiver if you still need it a bit later.

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When I read again I am convinced that this is a non-problem. My indoor laptop gets two bars on the windows utility most days and so what ! It works fine.

Your numbers indicate that you should have a good enough connection for internet.

Cheers, Steve

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