Question

Hi,

I am going to buy a dual-sim/gsm router like RUTX14 and will use it inside my caravan during travels. I need as best quality (latency, speed) internet as reasonably possible (I will use it for video meetings and tracking live market data etc while being outside of cities).

I have issues deciding which antenna(s) to use.

First of all - I guess that bundled default antennas are not the best for my case - i think i need to place antenna(s) on the roof instead of inside because a) my caravan (especially roof) has metal structures and b) roof mounting would be higher.

That means I need extension cables for the antennas. But isn't some signal lost in the extension cables themselves? Is there any significant loss comparing no extension cables, 1meter, 2meters, 3meters, 5meters?

Placement. My first guess was that most optimal way is to place the antennas as far as possible, like if we need to mount 4 antennas (sim1/sim2 x main/aux) best would be to place them on the different corners of the caravan. But I found antennas like this which have everything in one package:
* Teltonika PR1KCO28 tinklo antena 28 dBi https://www.senetic.lt/product/PR1KCO28
* QuWireless QuSpot for Teltonika RUTX12/RUTX14 (QUSPOT_RUTX12) https://www.katalita.lt/prods/details/quwireless-quspot-for-teltonika-rutx12-quspot_rutx12.html?utm_source=kaina24.lt&utm_medium=referral
questions:
do they not interfere each other? are they not getting the same signal making AUX antennas redundant/useless?

thanks.

Answer 1

Hello,

But isn't some signal lost in the extension cables themselves?

That is correct, the longer the cable, the higher the loss, however, how much of the signal is attenuated also depends on the characteristics of the cable itself, as each has a different loss over distance value. You can also find online loss calculators such as this for evaluation. As a general rule of thumb it is suggested not to exceed cable lengths of 10m, but you should always try keep it as short as possible.

Do they not interfere each other? Are they not getting the same signal making AUX antennas redundant/useless?

In general one of the AUX inputs of EG12(RUTX14) modem is diversity input, used for reception only. The necessity for this AUX antenna comes from assumption that if a signal experiences a null at a certain spot due to destructive multipath interference, it will still be possible to receive that signal at some other spot of the area as it is unlikely to be a null at some other place. However, situations like these are mostly experienced at cell coverage edges or spots, where signals struggle to penetrate. There are various recommendations of antenna spacing, ranging from fractions of a wavelength to several wavelengths, but I lack expertise to state specific numbers, however, as you have suggested, it can be considered redundant to use AUX antenna under good coverage conditions. 

A thing to note though, is that RUTX14's modem has support for 4x4 MIMO, and having all of the antennas attached should provide increased throughput due to the device being able to establish connection over several downlink data streams.

As for the antennas you have listed, I would suggest to simply concentrate on their performance characteristics, and whether they apply to your application requirements.

Best regards,