![]() Once you have found a suitable range of cables you need to chose the physical size, smaller cables will be easier to manage but lossier. You need to buy a cable that is designed for the frequency range. It depends very much on the cable type you buy. Might as well throw the antenna away at that point. And absolutely do not cut the connectors off and try to splice the coax. Very minor-seeming mistakes with connector assembly can cause huge losses at these frequencies. Buy cables with the right connectors already attached. One last tip: Don't try to assemble cables yourself. Note also that you want the power ratio, not voltage.) Here's a calculator (found at a cable dealer) that covers a wide variety of table types.Īnd to convert dB to ratios (or back), try this (Note, since this is signal loss we're talking about, enter the dB number as a negative number before pressing "calculate". You can find data sheets (with signal loss graphs) and calculators for various types of microwave coax all over the web. These cable types aren't rated at all for use above 1 GHz. For 5 Ghz it will be much worse.ĭon't even think about using RG59 (the older, thinner coax that used to be used for TV cable and antennas and commonly is seen with "F" or BNC connectors attached it's not even the right impedance) or RG58 (the right impedance, but still very lossy at these frequencies). ![]() With 7.5 feet, loss will be only 3 dB (you lose half of your signal).Īll of the above numbers are for the 2.4 GHz WiFi band. your signal is now about 1/16 the power that it was). So if you use 30 feet of LMR100 cable, your loss will be 12 dB (i.e. The loss in dB is linear with the cable length. With LMR400 cable, your loss would be only about 1 dB! (But that cable is more expensive, and also a lot less flexible = more difficult to install.) That's equivalent to dropping power to just 25% of what it was. ![]() At 2.4 GHz (the common WiFi band), 15 feet of LMR100 will result in signal loss of about 6 dB. (So will the connectors that you'll need to connect another length of cable to this one.) As Burgi and DavidPosthill said in the comments, how much it's reduced for a given length depends on the cable and the frequency.Ī common relatively inexpensive cable for short runs of WiFi antennas is LMR100. Any increase in cable length will reduce signal strength. ![]() Phone: +1 8 within the US or +1 8 outside the US. For urgent issues we are available at these times by phone: In this case start the serial interface to the IMx device and use this time the following command text:Ĭmd get wf/rssi Contacting SKF Technical Support Groupįor further assistance please open a support case using the Technical Support group's self-help portal at Once your support case is submitted, a technician will contact you to begin working on your issue. Rather than using the Observer client as described above, an alternative is to use the Online device configurator, software tool. In the example response shown, -60 dBm would be considered a good or very good signal strength, if it were -50 dBm or higher it would be considered excellent and the lower limit of acceptability is likely in the region around -70 dBm. Being a negative value the closer the dBm value is to zero, the stronger the signal strength. The response shown above is the received signal field strength in dBm. The main Command result area should update with the outgoing command string and the response received. In the Command line entry field at the bottom of that window enter: Requires Observer 12.2 or later and the IMx device must be configured to use WiFi for its network connection.įrom the IMx/MasCon devices dialog (On-line > IMx/MasCon devices) select the target IMx device and press the Command button to open the Command window. This article provides information on how to request a WiFi signal strength indication (RSSI) from an IMx-8Plus or IMx-16Plus device using the Command function in Observer.
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