Panel antenna for GSM-R band.
The modernization of České dráhy includes the coverage of the corridor and other tracks with a GSM-R signal. DCom developed and supplied antennas for this project as well. This created competition for the well-known manufacturer of GSM antennas Kathrein. However, ZZ900MHZG2x18.5D30 is directly designed for GSM-R and thus shows better gain parameters and directional diagram.
There are not many differences between classic GSM and GSM-R and most of them concern security and reliability. The basic principle and features of the system remain the same. One of the big differences lies in the way the area is covered. Unlike conventional GSM, GSM-R base stations try to cover only a limited area in the immediate vicinity of the line, as consistently as possible without dead spots. Due to this, GSM-R cells are characterized by large mutual overlaps reaching up to half of the cell area, which would be inefficient with conventional area GSM. This is so that the mobile station is served really reliably and in any place. Of course, the coverage also includes tunnels, bridges and often complicated sections of the track between hills and rocks.
Due to the fact that the density of GSM-R users will not be so high, the cells can be quite large, more precisely long and narrow. Therefore, directional antennas are used on very high masts. The method of coverage is also related to modifications of the GSM system for higher speeds of mobile stations. The GSM-R system also handles speeds over 350 km / h, while classic GSM is designed up to 250 km / h.
Other differences are in the offer of services. The GSM-R system allows setting the priority levels of established connections for the purposes of dispatching, which means that some types of calls are more important than others and take precedence over less important ones. Another service is group connections, where it is possible to connect to a whole predefined group of users. These are features taken from mass radio systems such as TETRA.
And last but not least, the GSM-R also has a difference in the frequencies used. Bands below the intervals for classic GSM are reserved for railway GSM, namely 876 – 880 MHz for uplink and 921 – 925 MHz for downlink. Channel width and other features are the same as GSM.
Electrical and mechanical parameters:
Frequency band (MHz): 880-960
Gain (dBi): 2×18.5
Beam angle in the H plane (°): 30
Radiation angle in the E – plane (°): 15
Unwanted emission suppression (dB): better than 30
Standing wave voltage factor: less than 1.5
Nominal impedance (Ω): 50
Input (connector): 2x 7-16 female (from below)
Polarization: + 45 °, -45 °
Maximum power (W): 500
Dimensions (height x width x depth mm): 1300x560x120
Weight (kg): 23
