Print version

6. Installation

6.1. Line of sight test

Before you install the device to a mast tube, verify visually that the view in the direction of the remote unit is unobstructed.

Line of sight considerations:

  • Free Fresnel zones. Signal needs space wider than the diameter of the antenna.

  • Trees at the lower end of the Fresnel zone. They will be taller in a few years.

  • Possible building development.

  • Objects in the close proximity of the antenna such as edges of other antennas, their mounting racks, edges of the roof.

6.2. Antenna mounting

6.2.1. Mounting methods

  • Mounting on the mast tube can be achieved by:

    • right-side mounting or

    • left-side mounting

  • Mounting the FOD unit for antenna polarization can be achieved using:

    • horizontal RX polarization mounting or

    • vertical RX polarization mounting

       In both cases mount the unit with the connectors facing downwards at an angle.

Horizontal RX polarization – see the arrow sign

Fig. 6.1: Horizontal RX polarization
– see the arrow sign

Vertical RX polarization – see the arrow sign

Fig. 6.2: Vertical RX polarization
– see the arrow sign

Left-side mounting – horizontal RX polarization

Fig. 6.3: Left-side mounting
– horizontal RX polarization

Right-side mounting – vertical RX polarization

Fig. 6.4: Right-side mounting
– vertical RX polarization

Right-side mounting – horizontal RX polarization

Fig. 6.5: Right-side mounting – horizontal RX polarization

Changing the mounting method

An antenna bracket is supplied as standard partly assembled, and ready for right-side mounting.

On changing the Jirous antenna bracket for left-side mounting the adjustment bolt (part No. 11) and swivel bolt (part No. 6) need to be unscrewed, then shift the bracket body (part No.5) to the other side of clamp plate (part No. 4), (do not turn upside down) and then insert bolt (part No. 6) into the second hole on the mounting plate holder and through the same hole on the clamp plate and secure in place with the nuts. The adjustment bolt (item No. 11) and nuts are switched to the other side of the clamp plate (part No. 4). It is also necessary to switch the hanging bolt (part No. 7) on the antenna mounting plate to the second hole so that after switching sides with the antenna it is on the top again.

In the case of the antenna when changing the method of mounting from right-side to left-side it is only necessary to rotate the plastic cover of the antenna. This is not only important from an aesthetic point of view, so that the RACOM logo is not upside down, but also because there is a discharge channel on the lower edge of the dish (except for ø380 mm dishes).

Changing the mounting method

Fig. 6.6: Changing the mounting method

When changing the polarization from horizontal to vertical only the FOD unit needs to be turned through 90° around the central antenna pin by unscrewing the four bolts on the dish using a No. 6 Allen key.


The RAy2-17 and RAy2-24 links are equipped with a polarization duplexer and work in both polarizations simultaneously, see Cross polarization. One side of the link must therefore be installed in vertical polarization and the other in the horizontal polarization.

6.2.2. Mounting the FOD unit on the antenna

RAy2 microwave bridge equipment is generally supplied as several component parts packaged separately in a box.

  • Two parabolic antennas with assembled mounting plates. There are also 4 screws in a small plastic bag in the box.

  • Two brackets for mounting the antenna to the mast.

  • Two FOD stations, each separate in a box, in a single package.

  • Other accessories based on the order placed (for more detailed information see chapter Chapter 4, Accessories)

A No. 17 spanner and a No. 6 Allen key are required for mounting the mechanical parts of the antenna. Spanner No. 17 serves for precisely setting the direction of the antenna. Both spanner and key can be found in the RAy Tool set for installing RAy2 microwave bridges.
It is advisable to lightly lubricate the retaining screws eg. by the supplied grease.

Close up image of the mounted bracket showing numbered parts

Fig. 6.7: Close up image of the mounted bracket showing numbered parts

  1. Prepare the antenna bracket based on the diameter of the mast tube. For smaller diameters face the bent part of the saddle plate (part No. 3) inwards. For larger diameters it should face outwards. Screw the bolts (part No. 1) into the clamp plate (part No. 4) so that they protrude approx. 1 cm through the clamp plate. Clamp the saddle plate to the mast by tightening the nuts (part No. 2) on the bolts.

    Position of the saddle plate for ø 40–80 mm

    Fig. 6.8: Position of the saddle plate for
    ø 40–80 mm

    Position of the saddle plate for ø 65–115 mm

    Fig. 6.9: Position of the saddle plate for
    ø 65–115 mm

  2. Slide the antenna bracket onto the mast tube and clamp to the mast by tightening the nuts.
    Recommendation: Keep the gap between the two saddle plates (part No. 3) as wide as possible, so the horizontal angle adjustement screw can fit in this gap. The range of horizontal adjustement is consequently wider. This has a bigger effect when the mast diameter is smaller.

    Attaching the bracket to the mast tube

    Fig. 6.10: Attaching the bracket to the mast tube

    Bracket on the mast tube

    Fig. 6.11: Bracket on the mast tube

  3. Screw the hanging bolt (part No. 7) into the upper hole of the mounting plate so that the antenna can be hung on the mounting plate holder. Hang the antenna on it and tighten the lower bolt. (part No. 8)

    Hanging the bolt on the holder

    Fig. 6.12: Hanging the bolt on the holder

    Correct position of the mounting plate

    Fig. 6.13: Correct position of the mounting plate

  4. Tighten both bolts to the plate before continuing with installation to prevent any unnecessary movements of the equipment. Before precisely adjusting the vertical direction of the antenna upon completing installation it will be necessary to unscrew them again as the lower bolt (part No. 8) passes through the adjustment block and the upper one (part No. 7) serves as the axis of rotation.

    Tightening the upper bolt to the mounting plate

    Fig. 6.14: Tightening the upper bolt to
    the mounting plate

    Tightening the lower bolt to the mounting plate

    Fig. 6.15: Tightening the lower bolt to
    the mounting plate

  5. Before installing the FOD unit on the antenna first unscrew the 4 bolts on the back of the antenna enough so that the unit can be slid on to them. Then check whether the “O” ring is correctly fitted on the antenna pin, and make sure it is not damaged and has been lubricated with grease – see Section 6.2.3, “Lubrication and preservation of the antenna pivot”. Then remove the protective plastic cover from the central pin of the antenna and fit the FOD unit to it carefully so as not to damage the “O” ring. Secure it in place with the four bolts. Carefully ensure the correct polarization of the antenna – see Section 6.2.1, “Mounting methods”. Finally tighten the bolts with a No. 6 Allen key.

    Dish before installing the FOD unit

    Fig. 6.16: Dish before installing the FOD unit

    Tightening bolts on the FOD unit

    Fig. 6.17: Tightening bolts on the FOD unit

  6. The precise horizontal direction the antenna is pointing in can be adjusted using the bolt with two nuts (part No. 10 and 12). Once the direction has been set the antenna is fixed in place by tightening the nuts against the bracket to prevent further movement of the antenna. The vertical direction the antenna is pointing in can be adjusted by turning the fine adjustment bolt (part No. 9) by the bracket mounting plate. After selecting the correct direction the position is secured by tightening the bolt – see point d. (part No. 7 and 8). The correct position in both directions is found by monitoring RSS, see Section 6.5.2, “Directing antennas”.

    Horizontal adjustment of the antenna direction

    Fig. 6.18: Horizontal adjustment of the
    antenna direction

    Vertical adjustment of the antenna direction

    Fig. 6.19: Vertical adjustment of the
    antenna direction

  7. After pointing the antenna in the right direction tighten the bolts on the bracket on the axes of rotation (part No. 6 and 11). Then check again that all other bolts have been sufficiently tightened. We can now proceed to connect the FOD unit to the user network.

    Tightening the axis at the fine adjustment bolt

    Fig. 6.20: Tightening the axis at the fine
    adjustment bolt

    Tightening the axis at the bracket

    Fig. 6.21: Tightening the axis at the bracket

6.2.3. Lubrication and preservation of the antenna pivot

Before fitting the FOD unit bush onto the antenna pivot ensure that the “O” ring (part No. 1) is in the correct position. It is also essential to prevent moisture getting in between these two parts. This moisture could cause oxidation which would complicate disassembly of this mechanical coupling in the future. For this reason we need to treat these surfaces with the grease which is supplied in the box marked “SILIKONOVE MAZIVO”. If you use a different grease for lubrication then it should be a Teflon or a silicon grease.

Grease points on the antenna pivot and FOD unit bush

Fig. 6.22: Grease points on the antenna pivot and FOD unit bush

Grease both the internal area of the bush on the FOD unit (2) and the “O” ring (1) with a thin even layer that allows the pin to slide easily into the bush without damaging the “O” ring. The layer has to be really thin and even to ensure no lubrication is pushed in to the waveguide. A little bit more lubrication could be applied only in the area (3) beyond the “O” ring on the antenna pin to optimally fill the small gap (max. 0.1 mm) between the pin and the bush to prevent leakage of moisture and water inside the unit. Installation should be carried out according to the antenna installation description – see point f of this description.
The tub with grease is supplied with the RAy2 units.

6.2.4. Flexible waveguide

Any type of antenna may be connected to the RAy2 unit using a flexible waveguide. Flexible waveguide mounting kit can be ordered as an accessory part.

Flexible waveguide assembly

Fig. 6.23: Flexible waveguide assembly

6.3. Connectors assembly

The FOD communication unit can be connected to the user network by metallic or fibre Ethernet cable.

The unit is equipped with those connectors:

  • ETH1+POE – Gigabit metallic Ethernet port. This port can power the unit with any Power over Ethernet power source working according to IEEE 802.3at standard.

  • ETH2 – Slot for user exchangeable SFP module. A wide range of optical modules is available. Both single or dual mode transceivers can be used. The SFP module with metallic RJ45 interface can be used as well. Please see the Important notice.
    The SFP status LED is located just next to the slot.

  • P – DC power connector.
    HW button for service purposes.

  • S – USB service connector.
    RSS voltage output connectors.

FOD communication unit connectors

Fig. 6.24: FOD communication unit connectors


Before connecting the FOD communication unit to the supply (to the user network) the FOD unit must be grounded according to Section 6.4, “Grounding”.

Assembly procedure:

Bushing and connector assembly

Fig. 6.25: Bushing and connector assembly

Bushing incl. lengthening and connector assembly

Fig. 6.26: Bushing incl. lengthening and connector assembly

  • Put on the cable: the nut No.1, rubber sealing No.2, bushing No.3 and O-ring No.4.

  • Attach the appropriate connector No.5 to the cable.

  • Plug the connector No.5 into the RAy2 unit.

  • Screw the bushing No.3 with the sealing O-ring into the RAy2 unit.

  • Move the rubber sealing (2) along the cable to fit in the bushing. Screw the nut (1) on bushing (3).

  • (If you use extension ring No. 6 lubricate its thread with grease.)

Disassembly procedure:

  • Release the nut No.1

  • Remove the rubber sealing No.2

  • Unscrew the bushing No.3 with O-ring No.4 (and extension No.6 with O-ring No.7).

  • Remove the connector.

  •     Warning:
    Should the rubber sealing No.2 become fastened to the cable the rubber sealing must be detached from the cable prior to unscrewing the bushing No.3. Failure to do so could cause the Ethernet connector inside the RAy unit to be damaged by cable rotation. We suggest you use a flat screw driver to release the rubber sealing No.2 from the cable.
    It is always better to optionally damage the bushing rather than damage components in the RAy unit.

Bushing including long lengthening

Fig. 6.27: Bushing including long lengthening

All necessary parts are delivered as an accessory SET-RAY2-CON-B. If the lengthening is needed use the extension SET-RAY2-EXT35 containing the parts No.6 and No.7 or use the longer extension SET-RAY2- EXT-F50.

The rubber sealing is delivered with three different internal diameters to fit different cable diameters. The rubber is diagonally cut to enable sealing of cables with pre­installed connectors.

  • All bushings and plugs (including the original plugs in the ports) must be fitted with O-rings and carefully tightened. Failure to do so may result in moisture accessing the internal workings. In such a situation the functionality cannot be guaranteed.

  • Before screwing extension ring (part No.6) into the RAy2 housing, lubricate its thread with grease.

  • When using other bushing or connector than the delivered there is a danger of bad seal or damaging the connector. Interior space can be small.

6.4. Grounding

The lightning and overvoltage protection system example, designed in accordance with regulation CSN EN 62305.

  1. Where possible the antenna should be located in an LPZ 0B protection zone with the use of a local or artificial air termination device for protection against direct lightning strikes.

  2. When meeting conditions for ensuring electrical insulation (distance from the lightning conductor) in accordance with article 6.3, it is not recommended to ground the load-bearing structure and antenna to the external air termination network. Grounding should be attached to the protective system of the internal LV wiring or grounded internal structures using a CYA 6 mm2 bonding conductor , see Fig. 6.28, “Grounding installation 1”

Grounding installation 1

Fig. 6.28: Grounding installation 1

Grounding installation 2

Fig. 6.29: Grounding installation 2

  1. If it is not possible to set up conditions of electrical insulation in accordance with article 6.3 we recommend connecting the load-bearing structure at roof level to the external air termination network via an 8mm diameter FeZn conductor and shielding the data cable before entry to the building with a grounding kit and CYA 6 mm2 conductor to the bonding bus, and if not already set up then also to the external air termination network, see Fig. 6.29, “Grounding installation 2”

  2. If there is not an external LPS on the building we recommend routing lightning current through an 8mm FeZn conductor to a common grounding system, or to a separate grounding electrode with a ground resistance up to 10 Ω.

  3. For limiting the overvoltage transferred over the data cable and into the building we recommend fitting surge protection at the interface between zones LPZ 0 and LPZ 1 connected via a CYA 4 mm2 conductor to the same grounding point as the antenna or the antenna mast.

  4. We recommend protecting the PoE power supply from overvoltage on the LV side with suitable class D surge protection.

The RAy2 unit is grounded to the flange at the fixing screws using an M8 screw. An insulated copper cable with a minimum cross-section of 6 mm2 terminated with a terminal lug is used as a protective conductor. The conductor should have a green/yellow plastic cover along its whole length. For grounding a RAy grounding kit can be ordered as an accessory (see Chapter 4, Accessories) containing a grounding terminal ZSA16, 40 cm grounding strip 15 mm wide, and 100 cm of cable with grounding lugs. For instructions on installing terminals see the datasheet RAy grounding kit. A qualified person must install the antenna.

Racom supplies surge protection for installation on Ethernet cables entering buildings. For more details see Surge protection.

Additional safety recommendations

  • Only qualified personnel with authorisation to work at heights are entitled to install antennas on masts, roofs and walls of buildings.

  • Do not install the antenna in the vicinity of electrical wiring. The antenna and bracket should not come into contact with electrical wiring at any time.

  • The antenna and cables are electrical conductors. During installation electrostatic charges may build up which may lead to injury. During installation or repair work to parts of the antenna lead, bare metal parts must be temporarily grounded.

  • The antenna and antenna cable must be grounded at all times. See Section 6.4, “Grounding”.

  • Do not mount the antenna in windy or rainy conditions or during a storm, or if the area is covered with snow or ice.

  • Do not touch the antenna, antenna brackets or conductors during a storm.

Grounding kit for S/FTP 4+2 cable

Fig. 6.30: Grounding kit for S/FTP 4+2 cable

Grounding kit detail

Fig. 6.31: Grounding kit detail

Protective conductor at the FOD unit

Fig. 6.32: Protective conductor at the FOD unit

Grounding the FOD unit

Fig. 6.33: Grounding the FOD unit

Protective conductor at the mast on a ZSA16 terminal

Fig. 6.34: Protective conductor at the mast
on a ZSA16 terminal

RAy grounding kit

Fig. 6.35: RAy grounding kit

Separated lightning conductor

Fig. 6.36: Separated lightning conductor

Note – It is always better not to install the microwave unit directly under the lightning conductor holders. There is lower probability of unit being polluted by birds.

It is necessary to install the Ethernet lead so that there is no excessive mechanical stress applied on the connector bushing:

Example of a correct lead installation.

Fig. 6.37: Example of a correct lead installation.

6.5. Start up

Connect a power supply to the installed FOD unit. Connect the device to be used for configuration via WiFi or ethernet cable. Access the configuration menu using browser or Alignment tool.

6.5.1. Noise on the site

This is particularly true for installation of links working in free bands, where the user has no secured frequency.

Analyse the level of noise in the individual channels using the spectrum analyzer under Tools – Live data – Frequency spectrum analyzer. If necessary adjust the choice of working channel on the basis of the results.

While doing so respect the rule that in one location all units emit a signal in the Upper part of the range and receive it in the Lower part of the range, or the other way round. A transmitter must not be installed in the part of the spectrum where other units function as receivers.

6.5.2. Directing antennas

  • For first antenna alignment, use a narrow channel, low modulation and high power where possible.

  • ATPC and ACM functions should be switched off (prevents Tx power fluctuations during alignment).

  • Where possible adjust both ends of link simultaneously to speed up the process.

  • Alternate adjustments at both ends of link in small increments both horizontally and vertically to establish position with strongest signal whilst looking for maximum main signal (see paragraph on main & side lobes).

  • RSS measurement chapter provides overview for available methods to measure RSS.

RSS measurement

To align antennas accurately connect a PC, tablet or mobile and use the diagnostic and measurement capabilities built in to the RAy unit. There are 4 tools available to support measurement of the 2 basic parameters for optimum antenna alignment: RSS (Radio Signal Strength) and SNR (Signal to Noise Ratio):

  1. Voltmeter – indicates local RSS

  2. RAy Tools smartphone application – indicates RSS, SNR – Local & Peer

  3. Antenna Alignment Tool web page – indicates RSS, SNR – Local & Peer

  4. Bar graph on Live Data page inside web manag. – indicates RSS, SNR, BER – Local & Peer

Before antenna alignment starts it is recommended to find out RSS and SNR values from the link design for the installed link or calculate these values yourself. There are 4 methods available with increasing levels of accuracy:


 RAy units support traditional antenna alignment using a voltmeter measurement representing RSS in dBm (only for a local unit). Connect a voltmeter with the range 2V DC via connectors to the operational unit and adjust antennas to the lowest indicated voltage. Voltage is calibrated according to signal strength. E.g.:
RSS -65 dBm corresponds to voltage 0.65 V,
RSS -80 dBm corresponds to voltage 0.80 V etc.
RAy Tools – smartphone application

RAy Tools is an application described in detail in Chapter 9, RAy Tools app for Mobile devices. Module Alignment displays RSS and SNR for both local and peer RAy unit. All key functionality in this module performs an identical function to Antenna Alignment Tool described in Section 7.6.2, “Live data”.

More about RAy Tools in Chapter 9, RAy Tools app for Mobile devices.

Antenna Alignment Tool – html page within unit management

Antenna Alignment Tool is optimized for devices with smaller displays. All values are refreshed ten times per second to enable smooth operation. The Antenna Alignment Tool is described in Section 7.6.2, “Live data”. The Tool is available on http://<ip>/tk, (e.g. for standard Ethernet ports, alternatively on in the case of connection through USB/WiFi or USB/Eth).

The Tool is accessible without any username or password.

Bar graph in web management

Within user management Tools / Live data / Bar indicators shows bar graphs of RSS, SNR and BER (Bit Error Rate) values for local and peer units. Values are refreshed every second or manually. See Section 7.6.2, “Live data” for detailed information.

NOTE: The BER value should be close to zero after antenna alignment.

Main and side lobes

Directional antennas have a specific angle within which radio waves can be transmitted or received (Angle of Tx/Rx).

The strongest signal is emitted in a forward direction; the main lobe is a graphical representation of its direction of travel and strength.

However signals are also emitted and received from unwanted directions through side lobes. In receiving antennas this is a highly significant factor contributing to the level of interference in a radio network (See Fig. 6.38, “Antenna lobe diagram”).

Fig. 6.39, “Signal strength graph” provides an indication of comparative signal strength from different beams emitted from a directional antenna.

Antenna lobe diagram

Fig. 6.38: Antenna lobe diagram

Signal strength graph

Fig. 6.39: Signal strength graph

Placing the antennas to the correct antenna alignment is very important to ensure the strongest signal is received:

Correct alignment diagram

Fig. 6.40: Correct alignment diagram


Radiation diagrams

Fig. 6.41: Radiation diagrams

Both antennas should be oriented towards each other using the peaks of the radiation diagram. Adjust the antenna alternately in the horizontal and vertical axes and monitor the resulting signal strength. Use the calculation of the expected RSS with the precision of several dBm as guidance. Side lobes transmit a signal ca 20 dBm weaker, see the Microwave link Calculation.

Radiation diagram – incorrect adjustment

Fig. 6.42: Radiation diagram – incorrect adjustment

The resulting RSS helps distinguish between the states A-A and C-C which appear similar. It also helps in situations where simple search for a maximum doesn’t work as shown in the illustration “incorrect adjustment”.

Real radiation diagrams are more complex, especially in that they run differently in horizontal and vertical axes. The basic steps for determining the main radiation lobe however stay valid. For example:

3D example of more complicated Radiation Pattern

Fig. 6.43: 3D example of more complicated Radiation Pattern

6.5.3. Link test

Basic parameters of the link are shown in the  menu Status – Brief, its quality is characterized by RSS and SNR. Values on Status screens can be refreshed manually by pressing the Refresh button or in real time with a period of several seconds after activating the Start button. Press the Stop button to terminate the periodic refresh of values.

The RSS, SNR and BER values can also be viewed on the screen Tools – Live data – Bar indicators. After pressing the Start button, values will be refreshed with a period of one second.

After installation, it is good to reset the statistics using the Clear stats button in menu Status – Detailed. This allows easier diagnostics of the link’s reliability over time.

6.5.4.  Parameters setup

After both antennas have been aligned, setup operation parameters for the link. In the case of links operating in the free band, setup the parameters based on survey results from the tool Tools – Live data – Frequency analyser. In the case of links operating on a licensed band, setup the parameters based on the assigned license:

  • Bandwidth

  • Channel Selection (TX / RX channel)

  • Modulation (TX modulation) – ACM is recommended. When selecting fixed modulation it is necessary to account for the fade margin. If fixed modulation is setup close to a possible maximum, then a deterioration in RSS could endanger the link both for data transfer as well as service access.

  • Transmit power (TX power), or ATPC

  • Verify and record IP addresses

  • Define access channels – https / telnet / ssh / ssh with password

  • Check the users password settings.

Restart both units by interrupting their power supply and verify the status of the link. This verifies that all parameters have been stored correctly in the memory.

Select Tools – Maintenance – Backup – Settings (Local & Peer) – Download and save the configuration to backup file “cnf_backup.tgz”.

This completes the installation. Further configuration can be performed remotely.