Talk:Wi-Fi How To
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And also a note to refer to page 37. One can start with an 8x10 passive and look up the gain at 2.6 GHz. Note that when you double of halve the size of the passive, you change it gain by 6 dB. So you can scale the 2.6 gig 8x10 down to 2x2.5 and estimate a number. Note that you are way off scale into the light pink color. That tinted area, Zone A, is a warning that you don't have enough gain to be sure you won't have multipath problems. | And also a note to refer to page 37. One can start with an 8x10 passive and look up the gain at 2.6 GHz. Note that when you double of halve the size of the passive, you change it gain by 6 dB. So you can scale the 2.6 gig 8x10 down to 2x2.5 and estimate a number. Note that you are way off scale into the light pink color. That tinted area, Zone A, is a warning that you don't have enough gain to be sure you won't have multipath problems. | ||
| - | + | --[[User:Dave M.|Dave M.]] 09:01, 6 December 2008 (UTC) | |
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| + | <table border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="100%" id="AutoNumber1"> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td><b><font color="#800000"><i>[[User:JeffLiebermann|Jeff's]] response:</i></font></b><p>Revised | ||
| + | number using most of his numbers and only correcting coax losses and</p> | ||
| + | <table border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" id="AutoNumber2"> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Transmitter</td> | ||
| + | <td> </td> | ||
| + | <td>+15dBm</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Transmit coax loss</td> | ||
| + | <td> </td> | ||
| + | <td>-1dB (about 0.5 meters with connectors)</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Transmit antenna</td> | ||
| + | <td> </td> | ||
| + | <td>+7dBi</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Free space loss</td> | ||
| + | <td> </td> | ||
| + | <td>-54dB at 5 meters</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Receive antenna</td> | ||
| + | <td> </td> | ||
| + | <td>+7dBi</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Rx and tx coax loss</td> | ||
| + | <td> </td> | ||
| + | <td>-1dB (about 0.5 meters with connectors)</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>2nd transmit antenna</td> | ||
| + | <td> </td> | ||
| + | <td>+8dBi</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Free space loss</td> | ||
| + | <td> </td> | ||
| + | <td>-60dB at 10 meters</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Rx antenna gain</td> | ||
| + | <td> </td> | ||
| + | <td>0dBi (internal laptop antenna)</td> | ||
| + | </tr> | ||
| + | <tr> | ||
| + | <td> </td> | ||
| + | <td>Delivered RX power</td> | ||
| + | <td> </td> | ||
| + | <td>??dB</td> | ||
| + | </tr> | ||
| + | </table> | ||
| + | Doing the arithmetic, I get -79dBm which is low but usable to about 24 | ||
| + | Mbits/sec. See my chart at [http://802.11junk.com/jeffl/rx-sens/receiver%20sensitivity.htm Wi-Fi Receiver Sensitivity].<br> | ||
| + | I don't want to get into a discussion on new material in the "talk" | ||
| + | section of the wiki. It belongs in the [[alt.internet.wireless|newsgroup alt.internet.wireless]]</a>.<br> | ||
| + | <i><b><font color="#800000">I've posted this in the newsgroup under the subject "Back-to-back antennas".<br>Please post any further discussion there. Thanks. --[[User:JohnNavas|John Navas]] 17:51, 6 December 2008 (UTC)</font></b></i></td> | ||
| + | </tr> | ||
| + | </table> | ||
