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ABDA 2.4 Antenna bidirectional Ethernet amplifier


An antenna bidirectional Ethernet amplifier is used together with radio modems of a 2,4 GHz range (IEEE 802.11b, g) operating in a semi-duplex mode and is intended for increasing of operation distance.
A built-in band pass filter enables operation in the conditions of strong noises.

Product Specifications
Common features Operating frequency range 2.4 - 2.5 GHz
Operation mode semi-duplex
Switchover time 0.5 μs
Operating temperature range -30...+50
Voltage supply 12 V
Current consumption 0.8 A
Breaking capacity (threshold) 0.5 mW
Weigh of amplifier 0,5 kg
Transmission amplifier Gain 27 dB
Output power 0.5 W, 1 W, 1.5 W
Maximum input power 50 mW
Output power automatic control available
Receiving amplifier Gain 27 dB
Noise ratio 4 dB
Output saturation power 10mW
Adaptable amplification no

Amplitude frequency characteristic of receiving amplifier in narrow and broad band

abda-1.jpg          abda-2.jpg
Amplitude frequency characteristic in narrow band                          Amplitude frequency characteristic in broad band



The Installation Order

Make sure that a possible voltage gip on the central cable core does not exceed 2,5 V before you start the installation. Measure the resistance of your drop cable with an ohmmeter - Rk (Ohm) having short-circuited the central core on the one end with a display. (fig. 4).


     Calculate the maximum voltage dip in the drop cable:
     Udip()=Rcable(Ohm)*Igain(), where the amplifier current Igain=0,8.
     If fulfilment of conditions is not possible a power supply with a higher voltage can be used, but not higher than +15V.
      Before N-type connector mating it is necessary that mating sizes should be checked. Use of connectors mounted on cables with discrepancy of mating sizes from the norm leads to mechanical damage of connector centre conductors, to RF parameter degradation of a coupler, it results in system nonoperability. Check the size given below on the mounted cable plugs (for example with a slide gage). It should be within a 5,2:5,6mm limit (fig.5). Plugs with a size of less than 5,2 mm should not be used.


     The centre conductor of the plug with the supernormal specified size cripples.

abda-6.jpg abda-7.jpg

There is no ground contact


Right connection


There is a ground contact but the centre conductor is deformed

     All the RF and power adapter connectors have RF sockets of N-type (7/3).
     1. Fasten the amplifier in the immediate proximity of the antenna. Connect ground to the amplifier.
     2. Connect an antenna cable to the amplifier connector "TO ANTENNA"/" ".
     3. Connect the drop cable to the connector "TO MODEM"/" " of the amplifier.
     4. Attention! To prevent ingress of moisture into the contact place both of the microwave junctions should be covered with a sealing material (SILIKON 100 or analogous).
     5. A connector "DC BIAS" of the power adapter should be connected to the drop cable.
     6. Make sure that the modem is de-energized.
     7. Connect the connector "RADIO MODEM" of the power adapter with the modem output IEEE802.11.
     8. Connect the power supply "AC power adapter" with a supply adapter "DF/PS-1A".
     9. Connect the power adapter to a 220V mains.
     10. The amplifier is turned on!
     Attention! The maximum output power from a modem port of the amplifier should not exceed the value of 50 mW.
     The amplifier power supply should be installed in a dry room.
     Remember that the energizing of the amplifier from the power supply device is effected over a central conductor of a coaxial cable. That is why the cable connecting the amplifier and the power adapter should be protected from ingress of moisture.

     Note (Radio Ethernet Recommendations are written up in the IEEE 802.11 standard):
     The standard IEE 802.11 presupposed initially a possibility of data transmission over a radio channel at a 1Mbit/s rate and at a 2 Mbit/s rate optionally. In the first case each bit (message symbol) is transmitted with the help of 11 chips of a V-code. The inverted and the forward sequence are used to transmit a unit message symbol and a zero message symbol correspondently (correlation reception is effected at the receiving end). Phase modulation is used at a 2 Mbit/s to save the symbol rate of 11Mbit/s (and the signal spectrum width of 22 MHz ~2/T, where T is a chip time) In addition to the IEE 802.11 standard there are the rates of 1 and 2 Mbit/s in the IEE 802.11b standard, besides the data rate of 5,5 and 11 Mbit/s is mandatory.
     While having a 11 Mbit/s data rate coding of 8 bytes with 8-bit complementary sequences is effected by the law 2+6, where 2 bits are transferred over a Q-channel and 6 bits define one of 64 sequences each of which is an 8-byte sequence. This 8-byte sequence is modulating over the I channel. Thus, the symbol rate is equal to the data rate, i.e. 11Mbit/s. While having a 5,5 Mbit/s stream (data rate is 5,5 Mbit), every 4 bits are represented as an 8-byte complementary sequence, i.e. symbol rate is 11 Mbit/s. Thus the IEE802.11b standard operates at the rate of 1Mbit/s, 2Mbit/ and 5.5 Mbit/s. A further rate increase led to occurrence of the EEE 802.11g standard which can support the rates of the "b" standard and operate on the frequencies of 6Mbit/s, 9 Mbit/s, 12 Mbit/s, 18Mbit/s, 24Mbit/s, 36Mbit/s, 48Mbit/s and 54mbit/s. The emission frequency range of ~20MHz is saved, modulation kind at great rates is from QAM to COFDM. Overloading of the range of 2,4...2,483 GHz caused the occurrence of the "a" standard which supports the rates of 6Mbit/s, 9Mbit/s, 12Mbit/s, 18Mbit/s, 24Mbit/s, 36/, 48Mbit/s and 54mbit/s in the frequency range of 5,15...5,35 GHz and 5,75...5,85 GHz. Restricted broadcasting powers of the range of 5,15...5,25 GHz ~50mW, 5,25...5,35 GHz ~250mW, 5,75...5,85 GHz ~1W. An approximate receiver sensitivity of a generalized modem IEEE 802.11 when 2 Mbit/s rate is -90 dBm, when 11 Mbit/s - -68dBm, when 22Mbit/s - -80dBm, when 54Mbit/s - -70dBm. An approximate transmitter power of the "generalized" modem IEEE 802.11 is 10...50mW. As far as the two modems connected directly via a cable are operable the dynamic range of the receiver is quite high.
     The network structure (MAC level - Medium Access Control) can be spot-spot - an IBSS mode (Independent Basic Service Set), BSS - all the stations link via a hotspot (there are 64 spots into a network), ESS (Extended Service Set) - an extended mode - several BSS networks, the hotspots interact, it enables traffic transfer from one BSS to another one. Unlike the "wire" Ethernet the radio Ethernet uses a technology of collision avoidance instead of collision detection.