There are two different functional designs:
These surge suppressors act like narrow bandpass filters. Only a narrow bandwidth is allowed to pass; other frequencies are shorted and discharged to ground. The design of these surge suppressors involves a direct and solid short-circuit between the centre and outer conductor of the coaxial device.
This short-circuit path, in the form of a coaxial line and of a precisely defined length, is designed to have an electrical length equivalent to one quarter wavelength (λ/4) of the signal frequency to be transmitted. As an alternating voltage of the correct frequency passes along the quarterwavelength shorting stub it experiences a 90° phase angle rotation, is then reflected totally at the short (180° phase angle rotation) and finally travels back along the quarter wavelength stub (= a futher phase angle rotation of 90°).
This represents a total phase angle rotation of 360°. The reflected signal and the incident signal are in phase and the operating signal does not see the short.
It is, therefore, not affected by it. However, if an alternating voltage of a different frequency is present, then these special factors are not given and the energy is short-circuited (= discharged to ground).
The method of operation of this device can be likened in principle to an electrical switch which, when a certain
voltage (d.c. sparkover voltage) is reached, switches the inner conductor to ground.
The design of this device consists of a Gas Discharge Tube installed directly between the inner and outer conductors of a coaxial line. When a higher voltage than the impulse sparkover voltage (=overvoltage)
appears on the line, the Gas Discharge Tube will fire and, depending on the prevalent energy, a glow discharge of between 75-90 V (current in milliampere range) or ionisation with an arc voltage of 10-20 V (currents ranging from amps to kiloamps) takes place. When the energy subsides (= is converted to heat), the discharge extinguishes itself automatically. After a cooling-down period of 30 secs., the Gas Discharge Tube is fully operational again. After several very high discharge currents occurring within a few seconds of each other, the functionality of the device may be impaired. It is recommended, therefore, that the gas capsules are replaced at certain intervals.
λ/4 stub protectors are used particularly in transmission paths between antenna and base station, as well as where transmit and receive signals use a common cable, involving high power signal levels.
In principle, the use of λ/4 shorting stubs in the receive path can also be recommended. In the event of a preamplifier being used at the Rx end, then it would be necessary to use the new special λ/4 shorting stub
protector with DC pass.
Fixing Kit (Order no. H06000A0024)
Return Loss Tri-Band-Type (J01125A0024)
1: 810 MHz = -27,3 dB
2: 960 MHz = -25,6 dB
3: 1710 MHz = -35,4 dB
4: 2200 MHz = -33,9 dB
Among the GDT Surge Surpressors there are 2 product lines available:
For frequencies up to 2.7 GHz and a maximum power of 300 W. The maximum discharge current is 40 KA (8/20 μs). The Gas Discharge Tube can be replaced.
For frequencies up to 6 GHz and a maximum power of 25 W. The maximum discharge current is 10 kA (8/20 μs).
The main usage of the surge suppressor with gas discharge tube is between the antenna and the base station. For high power signal transmission lines, λ/4 surge arrestors are recommended, as the non-linear characteristics of the gas cartridge can produce intermodulation products.
Generally speaking, the spark-over voltage of the discharge tube should be kept as low as possible. However, in order to avoid an unintentional ignition of the tube, the spark-over voltage should be at least twice the peak
voltage occuring under normal working conditions.
Other metal parts
Ohter metal parts
|Coupling torque Series N
Coupling torque Series 7-16
Durability (mating cycles)
|Thermal and Climatic Characteristics|
|Series N||Series 7-16|
|Category to DIN IEC 68 Part 1||40/155/21||55/155/56|
|Protection class to DIN 60529||IP68||IP68|
|Series N||Series 7-16|
|Max. frequency||2.7 GHz||2.7 GHz|
|VSWR||< 1.2 (2.7 GHz)|
|Insertion loss||< 0.2 dB||< 0.1 dB|
|Impulse Discharge Current||2500 x 10 A (10/1000 μs)
1000 x 500 A (10/1000 μs)
5 x 20000 A (8/20 μs)
1 x 40000 A (8/20 μs)