Antennas

Antenna selection is extremely important and will greatly affect the performance of your streamer.

4G uses different bands depending on the location and provider. In those bands, different ranges are used for up/downlink.

You need to understand the topology of the area you are intending to use v3xctrl in.

If you are in an urban area, the PCB/Flex antennas will probably do the job, but in any other case a good omni-directional antenna will make a big difference.

Use cellmapper to find out more about your region. First set your location, then select your carrier and 4G - LTE as network. In the Band dropdown, you can already see the bands your provide is using in your selected area.

E.g.: Location set to "Vienna", Provider set to "A1 Telekom Austria - Austria - 2321", Network set to "4G - LTE". Bands Dropdown shows B1, B3, B7 and B20 - so those are the bands you will be interested in. But you can check in with finer granularity: Select the specific bands and see hom many nodes are still left on the map. In this case, B1 only shows a single tower which has not been seen for a significant amount of time, so we can exclude it. B3 and B7 are the most widely used in this area, but B20 also has a fair amount of nodes. So when looking for an antenna for this region, I would make sure that it performs well on those 3 bands.

LTE Band	DL (MHz)	Center	UL (MHz)	Center	Notes
B7	2620–2690	2655	2500–2570	2535	High-capacity urban (2600 MHz)
B3	1805–1880	1842	1710–1785	1747	Most common in cities (1800 MHz)
B20	791–821	806	832–862	847	Primary rural coverage, very common

You can see, that those bands have different bandwidths for up and downlink. When selecting Antennas, I would compare SWR at all those center frequencies. The best match would then be the one with the lowest SWR at all those frequencies.

Testing Antennas¶

This part is unfortunately not possible without dedicated equipment. You will need a VNA. A low cost option is the LiteVNA64. You will then save the s1p file and run the script to generate the graphs.

We run two separate measurements: 1. 600-1000MHz 2. 1500-1800MHz

Save two separate s1p files and join them manually. This is just so we have more samples per range.