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jabbadabbadahat
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RBM33G antena amplifying

Wed Feb 01, 2023 1:16 pm

Hello I have RBM33G + ME909s-120p + MPGSM6 and i wonder is there any way to amplify antena singal.
When I connect the antena to my lte modem the WATTAGE doesnt seem to change much even with spreadsheet info about 20W maxpower
 
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mkx
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Re: RBM33G antena amplifying

Wed Feb 01, 2023 7:31 pm

Per standard, LTE mobile devices are expected to transmit at around 23dBm. Which is 200mW. Even if we assume 50% efficiency of Tx power amplifier, that's around 0.5W when transmitting at its fullest. Add a Watt or so for DSP consumption (both Tx and Rx) and it's still less than 2 Watts. Ancient devices were much less power optimized and consumed a few Watts, making them unable to run off single USB 2.0 port power capabilities (0.5A at 5V equals 2.5W). I guess that modern DSPs can deal with single LTE carrier (200/50Mbps) while consuming far less than one Watt.

The specification says board consumption is 5W (max), those 24W is max with attachments included (miniPCIe slots ocupied, m.2 slot ocupied, USB ports fully loaded etc.).
 
r00t
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Re: RBM33G antena amplifying

Wed Feb 01, 2023 9:56 pm

Remember, good antenna is your best amplifier. Unless you have mobile setup, using omni antenna is just a waste of power. Patch, yagis or directional dish antenna with proper gain would give you much better results...
 
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mkx
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Re: RBM33G antena amplifying

Thu Feb 02, 2023 2:34 pm

The nice thing about directional antennae, used in mobile networks, is that using it doesn't limit Tx power from transmitter.[*] So unlike in WiFi (where EIRP is limited pretty low and using high-gain antenna doesn't end up with stronger signal, but rather greater sensitivity of receiver) using directional antenna for LTE connection actually helps. Specially so as eNodeB (base station) has already far greater Tx power than any of mobile clients and already has much better Rx sensitivity. And adding some gain on client side actually helps with making link more symmetrical in terms of link budget (symmetrical between Tx and Rx).

[*] I don't know if in professional mobile networks (where operator pays expensive license for using portion of frequency spectrum) there are EIRP limits per cell, but even if there are some they are very high, definitely above 50dBm = 100W. There are some limits per transmission site and they are quite high, can be upwards of 1kW depending on country. And there are some safety margins, which may limit allowed radiated power to lower values if general public can get into the space with stronger EM field, because this general limit is geared towards public health and safety. Those margins are generally frequency dependent. Partially because effects on human body vary with frequency and partially (I suspect) due to lobbying of existing transmitters operators not to be forced to reduce transmitter power due to new regulations.

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