Extending antenna cables

While it's possible to extend the cables on antennae using additional cable, you have to weigh the increase in signal that is obtained by repositioning the antenna against the increased signal loss caused by more cable. Depending on the application, it's possible that the net signal strength will be worse with the longer cable.

Because of this, the most important specification is that the cable be low loss. Cable loss is specified in dB per 100 feet, at a test frequency. For cellular applications, the applicable test frequency is 1 GHz (cellular is at roughly 800-900 MHz).

For example, using RG58C/U cable (same as the standard factory cable on the antenna), the loss is specified at -20 dB per 100 feet at 1 GHz. A 10 meter cable is 1/3 that length, so about 1/3 the loss, or -7 dB. So, if you get 7 dB of improvement in signal by moving the antenna and adding 10 m of cable, that is just break-even at the logger - there is no benefit. Before adding the extension, be sure to note the signal strength using the antenna test so you can tell if you've made an improvement by repositioning the antenna. Following are the specifications for the cable and connectors used on the iPack:

Cable is coaxial cable, 50 Ohm impedance. We use type RG-58 A/U. RG-8A/U is much lower loss, but is physically huge (about 10 mm diameter!). Connectors are type SMA. The antenna is male, the Symphonie logger is female. NRG sells no standard cable extensions, but they are readily available from electronics supply stores.