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Antenna Installation Guide

Antenna Installation Guide

 

 

Revision History

Revision

Date

Details

1.0

11-May-2015

Initial draft

1.1

19-Jan-2018

Updated with ZCG CM Series Antenna

Scope

This document provides guidelines for electrical contractors installing the receiver antenna for Taggle Systems LPWA receivers.

 

Equipment Description

Taggle Systems has developed a proprietary Low Power Wide Area (LPWA) radio system for use in a variety of telemetry and location applications including Automatic Meter Reading (AMR), environmental monitoring, asset location and security monitoring.

The system is a one-way Wireless Wide Area Network (WWAN) which operates in the 900MHz Low Interference Potential Device (LIPD) class licence band (915-928MHz), sometimes also referred to as the 900MHz ISM band.  Battery powered transmit devices send short low power data packets at regular intervals (typically hourly) which are picked up by the receive antenna connected to a Taggle LPWA receiver.  The receive antenna is a critical system component and careful consideration must be given to the location and type of antenna to maximise system performance.

A well-installed antenna should provide at least 2km outdoor receive range from standard low power (30mW) Taggle transmitters in typical urban environments and at least 5km outdoor range in less dense rural environments.  Reliable outdoor receive ranges of over 20km are achievable in rural areas for antennas installed on very high sites which provide near Line Of Sight (LOS) paths to most transmitters.

Antenna Types

Taggle Systems uses a variety of antennas depending on the exact receiver location requirements. The four most common antennas used are described below.

CMG1600AM

 

 

The ZCG CMG1600AM is a commercial-grade 8dBi gain Omni-directional collinear dipole antenna. This antenna is a single band (890-960MHz) and has an integrated N-type connector. It is an effective solution for most applications and is also easy to install due to its light weight (700g) and low wind loading.  

The specifications for the ZCG CMG1600AM are shown in Figure 1 below.

 

COL2199

 

The RFI COL2199 is a commercial-grade 9dBi gain Omni-directional collinear dipole antenna. As of January 2018, the COL2199 has been discontinued and superseded by the multi-band COL8199, which is a less suitable choice as the multiple reception bands will increase potential interference to the receiver. Therefore it is recommended to use the CMG1600AMG for all new installations.


The specifications for the COL2199 are shown in Figure 2 below.

QB900-11V

 

The NH Microwave QB900-11V is a carrier-grade 11dBi gain Omni-directional collinear dipole. It is used in applications requiring maximum coverage area, but requires a more substantial mounting structure than the COL2199 due to the increased weight and wind loading. Specifications are shown in Figure 3 on the left

PB900-12-180V

 

 

 

The NH Microwave PB900-12-180V is a carrier grade 12dBi gain directional panel antenna with a 1800 beamwidth. It is generally used in pairs for high density locations where two receivers are deployed in 1800 opposing segments. Specifications are shown in Figure 4 on the left

Radio Survey

Prior to antenna installation, it is recommended that a radio survey is undertaken using a portable spectrum analyser to identify any potential sources of RF interference.

The Taggle LPWA receiver has a high sensitivity RF input stage, which is susceptible to both in-band and out-of-band (OOB) interference. The receiver employs proprietary Active Interference Cancellation (AIC) technology to minimise in-band interference caused by other radios operating in the 900MHz LIPD band, in particular Frequency Hopping Spread Spectrum (FHSS) data radios. However, AIC is only effective for distant sources of interference. Additionally, the receiver has provision for installation of an optional cavity filter before the RF input stage to minimise interference from very strong OOB interferers. However, the cavity filter is relatively costly and the insertion loss from the filter will reduce the receiver sensitivity by 1-2dB; therefore it should only be used if required.

The following criteria should be considered when selecting potential receive antenna sites based on the radio survey:

  1. Co-location on sites with existing 900MHz LIPD class licence transmitters is not permitted.

  1. Sites with in-band interference levels from FHSS radios exceeding -70dBm/MHz should be avoided.

  1. Sites with continuous wideband interference in the 900MHz LIPD band greater than

-100dBm/MHz, i.e. from another LIPD class licence Direct Sequence Spread Spectrum (DSSS) or OFDM data radios, should be avoided if possible.

  1. Any OOB interferer from 20MHz to 2.5GHz exceeding -20dBm/MHz will require a cavity filter.

  1. The cavity filter will not adequately attenuate adjacent channel OOB interferers operating from 928MHz to 930MHz (these are typically narrowband fixed data radio links), so avoid deploying the receive antenna directly near this type of equipment.

 

Site Selection

The following physical criteria should be considered when selecting potential receive antenna sites:

  1. Geographical height is the most important criteria – the higher the antenna relative to its surroundings the better.

  1. The antenna should clear surrounding clutter such as trees, nearby buildings, and other equipment on the mounting structure, to provide an uninterrupted view of the desired reception area.

  1. Sites with direct access via stairs or ladders are preferable to sites requiring costly access via boom lifts or cranes.

  1. Whilst the antenna is receive only and presents no inherent RF hazard, it generally should not be deployed in publicly accessible areas to prevent tampering or damage from vandalism.

 

Antenna Mounting

The exact mounting method for the antenna will depend on specific site conditions, however some general guidelines for common deployment scenarios are provided here.

For CMG1600AM, COL2199 and QB900 antennas the recommended mast type is 32mm Nominal Bore (NB) medium duty galvanised steel water pipe, which has an outside diameter of 42.4mm.

For PB900 series antennas the recommended mast type is 50mm NB medium duty galvanised steel water pipe, which has an outside diameter of 60.3mm.

Note that the dipole antennas have narrow vertical beamwidths (8-90) hence it is essential that the mast and antenna be absolutely vertical.

 

Guard Railing

Antennas are commonly mounted on water reservoirs, and the reservoir railing (if available) is often the most convenient mounting point.

The mast should be secured to a railing stanchion using two heavy duty galvanised parallel clamps (RFI type UC-1 or equivalent). One clamp should be used at the base of the stanchion and the second just below the top railing.

The maximum recommended mast length assuming 800-900mm spacing between the 2 clamps is shown in Table 1 below.

A typical railing mounted antenna is shown in Figure 5 below.

For installations requiring more height the mast length can be increased to 6.5m (the maximum length generally available for a single tube section), however the mast should be strengthened with at least one (and preferably two) diagonal stays attached approximately 2m from the top of the mast.


Guyed Masts

Receivers are occasionally deployed on assets such as pump stations or treatment plants where no adjacent high structure such as a reservoir or telemetry tower is available. In these cases a 4.5m guyed mast installed on the roof is a possible solution. Due to the limited weight and wind loading ratings of these masts they should only be used with CMG1600AM or COL2199 antennas.

A 4.5m guyed mast installation is shown in Figure 6 below.

Equipment part numbers and installation details can be found at http://www.rfiwireless.com.au/media/downloads/pdfs/mounting_accessories.pdf

 

Lattice Tower

Installation on lattice towers should be as high on the tower as safely possible. If the antenna is mounted below the top it should be mounted on a separate cross boom at least 1.5m from the tower itself. For CMG1600AM or COL2199 antennas a 32mm NB boom should be used, attached to the lattice tower with two heavy-duty clamps (RFI type UC-1 or similar). The antenna should be attached to the boom using a single right angle clamp (RFI type UNV or similar).

The antenna should not be mounted directly in the bore sight of other antennas on the tower to minimise interference.

An example lattice tower installation is shown in Figure 7 below.

 

Facia Mount

If access to the highest point of a building is possible CMG1600AM or COL2199 antennas can be mounted using a 1.8m facia bracket (RFI type HS72 or similar) as shown in the photo below.

Coaxial Cable Installation

The connection between the antenna and receiver should be made using LMR400 or CNT400 coaxial cable. This cable has a loss of 1.3dB/10m @900MHz and a minimum bend radius of 25mm, making it a cost effective and relatively easy to install solution that provides acceptable loss for intermediate cable run lengths.

The antenna cable length should be kept as short as possible to minimise insertion loss between the antenna and receiver. Try to keep the cable length below 15m if possible, and do not exceed 25m unless absolutely necessary, bearing in mind that any extra geographical height will generally provide more benefit to system performance than reduced cable loss from a lower height.

It is recommended that the coaxial cable be enclosed in 25mm flexible conduit in outdoor areas to provide additional weather resistance. Reinforced flexible conduit (Flexicon, Anaconda, or similar) should be used in areas susceptible to damage from birds.

The cable should be securely attached to masts using superior quality professional grade UV resistant nylon cable ties or stainless steel straps.

The coaxial cable should be terminated using N-type plugs designed for LMR/CNT400 coaxial cable. The recommended plug is an RFI type N-201, which is a solder-less crimp connector with a push-in spring finger centre pin. The coaxial cable should be stripped as shown in Figure 9 below.

The recommended stripping tool is an HT322S.

The crimping tool requires a 0.429” (10.9mm) crimp. A ratchet type crimping tool such as an
HT-336D2 is recommended.

Note the centre conductor should be chamfered and must be completely straight when pushing the coaxial cable into the N-201 connector centre pin. Alternatively, the centre pin can be removed from the N-201 connector by carefully pushing it out towards the back of the connector with a small screwdriver, and placing it onto the coaxial cable centre conductor prior to pushing the cable into the connector body.

After both ends of the coaxial cable have been terminated it should be measured with a cable tester if possible, prior to connection of the antenna and receiver. The cable loss should be in the range
(L/10 *1.3 + 0.5)dB +/- 1.0 dB, where L is the cable length in metres.

 

Connection to the Antenna

CMG1600AM, PB900 and QB900 antennas have integrated N-type sockets on the base of the antenna. The coaxial cable should be connected directly to the antenna with no loops. The connection should be sealed with silicone tape extending past the bottom of the N-type plug, and to the start of the flexible conduit if used. The end of the flexible conduit should be sealed with silicone adhesive to prevent water from running down the inside of the conduit.

COL2199 antennas have a 20cm RG-58 tail with an N-type cable socket. The coaxial cable should be connected then sealed with silicon tape and PVC tape. The RG-58 tail should be securely attached to the mast to prevent it carrying the weight of the CNT/LMR400 coaxial cable. If the coaxial cable is enclosed in flexible conduit a loop can be placed at the top of the mast to prevent water ingress, as shown in Figure 5 above.

 

Connection to the Receiver

The antenna connections to the receiver are housed in the cable management box on the bottom of receiver as shown in Figure 10 below. To access the cable management box remove the two hex bolts in the bottom of the main receiver enclosure and slide the front cover down then outwards.

Secure the antenna coaxial cable into the left-hand hole in the base of the box using a 25mm cable gland or conduit gland as required. The coaxial cable should be connected to the input of the Gas Discharge Tube (GDT) lightning suppressor.

Note: the 25mm gland must be fitted on the coaxial cable BEFORE the N-Type plug, as the plug will only fit through the gland nut, not the gland itself.