NB! Also read update, solving the problem, further down on this page!
Many of our customers who use D-Link DWL-900AP+ have reported problem with highly limited operating range. Many who have connected an external antenna have not obtained expected improvement. We have measured the output power from the radio. On the internal antenna, the output power is 17 dBm which corresponds to the datasheet. (The output power is adjustable in four steps to 10 dBm). On the external antenna connector (RP-SMA) the output power is 25 dBm lower, which decreases the range by about 95%. The result is that the radio traffic often still goes through the internal antenna, even though an external antenna is connected. There are a few plausible explanations: The measurements above explain why we have not been able to measure sensitivity on the receiver. This we usually do this by interconnecting two radios (non galvanic) through the antenna connectors. In these tests the signal path has apparently been through the internal antennas, in particular at weak signal levels. More information can be found on this page. We have not tested whether this appears on other D-Link models.
(Update 030829)
After discussions with Mr Mikael Salin at D-Link, we have made additional tests and found a solution to the problem: - The first test was done with hardware rev B1 and software ver 2.3. - The next test was done with hardware rev B1 and software ver 2.57. There is a setting in the software, where it is possible to choose "left antenna" or "right antenna", which refers to internal and external antenna (however, we do not know which of the antennas that is considered "left" and which is "right"). The signal is transmitted through the internal antenna regardless of setting. -The third test was done with hardware rev B1 and software ver 2.60. This time it works as follows: "left antenna" setting transmits through the external antenna. - Finally a test was done with hardware rev C1 and software ver 3.05: This time it also works, but opposite to the previous test, i.e.: "right antenna" setting transmits through the external antenna. It seems like the unit is delivered with the setting "diversity antenna". With this setting the signal transmits through the internal antenna. The unit D-link shipped to us came with software ver 3.05, but it is likely ver 3.02 that is delivered as standard. D-Link refer to the pages below: For more information contact Niklas Gunhamn. |
