What is the effect of antenna cable?

A rough calculation of the actual effect that changes to antennas, boosters and cables would make to your wireless network can be calculated quite easily. dBm and dBi, the units for power increase and power loss, can be added and subtracted from one another.

For example, the effect of adding a cable and an antenna:

               Our 6 meter cable has about a 3 dB signal attenuation (a loss)

                                                            +

               The antenna has 24 dBi gain (an improvement)

                                                            =

               21 dB (the overall improvement)

How much improvement is that? Outdoors, in perfect conditions where there are no obstructions an extra 6 dB will double the transmission distance. 12 dB will double it, twice over (I.e., multiply it times 4). So, for example, an Access Point, which can reach 120 meter under optimal conditions, might now be able to reach 1346 meter.

The 3 dB attenuation of the antenna cable means that, half of the output power of the radio will be lost in the cable and vice versa, half of the power coming from the antenna to the receiver will be lost. In a system the loss of the antenna cable will directly increase the noise figure of the receive path.

So, it is recommended to keep the length(loss) of the antenna cable as short as possible. Our outdoor amplifiers can be shipped with N-female antenna connector, which attachable to the N-male connector of the antenna without cabling. If this option needed please, email us at support@gemmicrowave.com.

In an amplificated system the loss of the coax cable between the amplifier and the radio will not worsen significantly the noise figure further, and the loss of the cable will be compensated effectively by the bi-directional amplifier.

In the above example, the Access Point might now be able to reach 1902 meter without the loss of cabling between antenna and radio/amplifier.

Inside of a building, there are many other factors that reduce wireless range. For hints about optimizing your existing antennas and wireless equipment, see Improving Wireless Range.