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Cellular Systems

GSM/3G Repeaters

FAQ - GSM, DCS, 3G repeaters

Mobile phone conversations in buildings are often difficult to carry on, if not impossible. This is due to the signal attenuation through walls, window panes, ceilings (underground). The problems occur in stores, tunnels, underground car parks, petrol stations, airport halls, hotels. A similar situation can be found in buildings located on the border range of base stations (recreational areas, mountains etc).
The solution to such problems is application of GSM, DCS, 3G repeaters - two-way amplifiers of cellular signals, which significantly improve the quality of data transmission.
In Poland, we organize courses for installers of such repeaters. After passing final exam, each successful candidate gets a special certificate.
Below we have collected frequently asked questions on installation of cellular signal repeaters and answers to the questions.
  • What is the principle of GSM, DCS, 3G repeater operation?
    • Repeaters are used to amplify signals of GSM, DCS or 3G and to distribute them inside buildings. Any repeater has to be connected to an outdoor antenna directed toward the base station of the particular network, and to indoor antenna/s distributing the amplified downlink signals and receiving uplink signals from the terminals (phones or modems).
GSM Amplifier/Repeater SIGNAL GSM-305
GSM Amplifier/Repeater SIGNAL GSM-505
GSM Amplifier/Repeater SIGNAL GSM-1205
GSM Amplifier/Repeater SIGNAL GSM-305 A6765
GSM Amplifier/Repeater SIGNAL GSM-505 A6775
GSM Amplifier/Repeater SIGNAL GSM-1205 A6785
DCS Repeater Signal DCS-500
3G Repeater Signal 3G-505
DCS Amplifier/Repeater
Signal DCS-500 A67120
3G Amplifier/Repeater
Signal 3G-505 A67105
  • How to choose a suitable repeater?
    • The basic information that one should know before purchasing a repeater is the kind of cellular service which will be used:
      • GSM, EGSM - used mainly outside cities, but also in many metropolitan areas; the bands ensure voice connections and low/medium speed Internet connectivity.
      • DCS - used mainly in cities (due to higher capacity of a single base station).
      • WCDMA (3G) - used in cities, ensures high-speed data transmission (HSDPA), video calls and other 3G services.
    • Another important information is how much area is to be covered with the amplified signal:
      • In the case of GSM/EGSM systems:
        • < 300m2 - the suitable device is Signal GSM-305 A6765,
        • > 300m2 but < 800m2 - the suitable device is Signal GSM-505 A6775 with several indoor antennas A741001,
        • > 800m2 up to 1200m2 - the suitable device is Signal GSM-1205 A6785,
        • > 1200m2 - the suitable device is also the repeater Signal GSM-1205 A6785, cooperating with several indoor antennas A741001.
      • In the case of DCS systems (Signal DCS-500 A67120) and 3G systems (Signal 3G-505 A67105), the repeaters can cover areas up to 500 m2 using single indoor antennas.
  • How to choose a suitable outdoor antenna and where to place it?
    • Suitable antenna type depends on the kind of service (frequency band) and distance from the base station.

    • It is very important not to use an antenna with too large gain which would dramatically increase the probability of overdriving the repeater and even pose a risk of parasitic oscillation, causing the device to be inoperative and interfering nearby base stations. One should observe the rule that higher gain of the outdoor antenna requires greater separation from the indoor antenna/s.

      • GSM systems:
        • The repeaters Signal GSM-305, GSM-505, and GSM-1205 require to use an antenna with minimized side lobes. The ideal choices are A741030 and A741020 (panel antenna).
      • DCS systems:
        • An ideal antenna in terms of looks and gain (DCS systems are used in metropolitan areas) is A741020.
      • 3G systems:
        • When the repeater Signal 3G-505 A67105 is located somewhere in a city center, the optimum antenna is A741020 (wide radiation angle); for installations outside the downtown, at distances over 5 km from the base station, the suitable device is the antenna supplied with the repeater (high gain and directivity, small side lobs).
GSM/DCS/UMTS Antenna: TRANS-DATA KYZ8.2/9.5
GSM/DCS/UMTS Antenna: TRANS-DATA KPV7.5/10
TRANS-DATA GSM/DCS/UMTS
KYZ8.2/9.5 A741030
TRANS-DATA GSM/DCS/UMTS
KPV7.5/10 A741020
  • How to choose and place indoor antennas?
    • When deploying indoor antennas, one should pay attention to the number of rooms that are to be covered by the amplified signals and the total area. During installation, it is important to keep large distance between the outdoor and indoor antennas. The installation should be started from the lowest level since it is often possible to cover two floors with antenna/s located on one floor. We offer three antennas from TRANS-DATA series, specially designed for cellular amplifiers: A741001, A741002 and A741020.
GSM/DCS/UMTS Antenna: TRANS-DATA DW3-A
GSM/DCS/UMTS Antenna: TRANS-DATA DW3-B
GSM/DCS/UMTS Antenna: TRANS-DATA KPV7.5/10
TRANS-DATA GSM/DCS/UMTS
DW3-A A741001
TRANS-DATA GSM/DCS/UMTS
DW3-B A741002
TRANS-DATA GSM/DCS/UMTS
KPV7.5/10 A741020
GSM/DCS/UMTS Antenna: TRANS-DATA KYZ8.2/9.5Two-way GSM SplitterTwo-way GSM SplitterTwo-way GSM SplitterGSM/DCS/UMTS Antenna: TRANS-DATA DW3-AGSM/DCS/UMTS Antenna: TRANS-DATA DW3-AGSM/DCS/UMTS Antenna: TRANS-DATA DW3-AGSM/DCS/UMTS Antenna: TRANS-DATA KPV7.5/10GSM Amplifier/Repeater SIGNAL GSM-305
An example of placing indoor antennas

Three-way GSM SplitterGSM/DCS/UMTS Antenna: TRANS-DATA DW3-AGSM/DCS/UMTS Antenna: TRANS-DATA DW3-AGSM/DCS/UMTS Antenna: TRANS-DATA DW3-BGSM/DCS/UMTS Antenna: TRANS-DATA KYZ8.2/9.5GSM Amplifier/Repeater SIGNAL GSM-305
Another example of placing indoor antennas

  • What are the proper cables and connectors?
    • GSM, DCS, 3G systems require high quality components: connectors - N-male E84130, N-female E84135, SMA RP male E84150, SMA RP female E84130 - designed for Tri-Lan 240 and Belden H-155 cables. The connectors can be used in installations up 6 GHz, so they ensure a wide margin of performance. They are characterized by low loss, high return loss and screening efficiency. Good impedance matching and screening efficiency of the cables and connectors are vital for the performance and stability of the system, limiting to a minimum incoming and outgoing interference.
SMA/RP female
E84155
SMA/RP male
E84150
N-male
E84130
N-female
E84135
      For GSM systems the suitable cable is Tri-Lan 240 E1171 or Tri-Lan 400 E1173, 3G or DCS installations require to use Tri-Lan 400 E1173.
Coaxial Cable 50 ohm: Tri-Lan 240 [1m]
Coaxial Cable (50 ohm): Tri-Lan 400 WLL [1m]
50 ohm coax
Tri-Lan 240 E1171
50 ohm coax
Tri-Lan 400 WLL E1173

  • How many users can simultaneously use the GSM, DCS or 3G repeater?
    • The maximum number of users depends only on the capacity of the base station of the particular cellular service.
  • Does the equipment simultaneously amplify signals of different operators?
    • It is possible - the repeater amplifies all signals of cellular operators which are correctly received by the outdoor antenna.
  • After installing a repeater, cellular connections are still being interrupted. What is the remedy?
    • Usually, the solution to this problem is to find a better location for the outdoor antenna, sometimes also for the indoor antenna/s.