FAQ - LTE, 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 or LTE 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, LTE repeater operation?

Repeaters are used to amplify signals of GSM, DCS, 3G or LTE 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 A6765	GSM Amplifier/Repeater SIGNAL GSM-505 A6775	GSM Amplifier/Repeater SIGNAL GSM-1205 A6785

GSM Amplifier/Repeater: Signal GDW-505 (EGSM, GSM, DCS, WCDMA, LTE) (without PSU)

GSM Amplifier/Repeater: Signal GDW-505 (EGSM, GSM, DCS, WCDMA, LTE) A6777

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 GSM, DSC, 3G, LTE systems (Signal GDW-505 A6777) 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).

GSM, DCS, 3G, LTE systems:

When the repeater Signal GDW-505 A6777 is located somewhere in a city center, the optimum antenna is A741021; for installations outside the downtown, at distances over 5 km from the base station, the suitable antenna would be A741031 (high gain and directivity, small side lobs).


TRANS-DATA LTE KYZ 7,5/8/10 A741031	TRANS-DATA LTE KPV 7/10

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 A741021.


TRANS-DATA GSM/DCS/UMTS DW3-A A741001	TRANS-DATA GSM/DCS/UMTS DW3-B A741002	TRANS-DATA LTE KPV 7/10 A741021

An example of placing indoor antennas

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.