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Glomex RA111AIS

Aerial designed and tuned specifically for use on the AIS frequencies at 162mHz .  A flexible and pliable stubby type just 5 cm long, this fantastic little aerial can be mounted low down e.g. on a stern rail and  won’t end up getting bent as a result of being leant over whilst deploying ropes etc. Mounting Low down is acceptable for AIS as there is no real need to see and be seen to the horizon – AIS being a close up collision warning system. It is interesting to see other vessels 20+ miles away but a vessel 20+ miles off will not be a collision hazard developing. We discuss this in greater detail in our aerials Blog which you can access by clicking the button below.

To buy, from the options: choose cable length and whether you would like 1 or both PL259 connectors fitted to the cable. If you choose 1 then the other will be in the kit but not fitted (the cable will be prepared and ready for the PL259).
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The importance of using the right cable

RG8X extra quality low loss cable

We don’t supply RG58, the cable normally supplied with these aerials, as it has significant losses over length. We use RG8X which is a good compromise between RG58 and RG213 cables. Whilst RG58 is suitable for short runs of co-axial cable, at 30 metres the losses may be noticeable. This is inevitable as all cables exhibit loss over length so ideally a cable should be chosen with the least losses but here there is a trade off as less loss will mean a cable with a thicker inner core, a thicker dielectric insulation and a more dense outer braid. This all adds up to a cable that becomes very expensive and also unwieldy and inflexible. RG213 is a good example – this is the cable that Radio Hams use – it has significantly lower loss over distance but it is expensive and when installing it is very hard to get around corners and into tight recesses as the cable is so inflexible.  RG8X (or mini8 as it is also known) is a good compromise, a much better cable than RG58, it has a thicker inner core, a thicker dielectric insulate and a much denser outer braid (see image) yet it is very flexible and is only 1.5mm thicker than RG58 (RG58 is 5mm, RG8X 7mm).  If you want the best low loss cable then go for RG213 or other similar specification cables but your installation is going to be very difficult and expensive – it all comes down to being a sensible compromise.

To make your installation easier if running cable through a bulkhead etc:

If you would like one end left prepared but unterminated for ease of cable installation through a bulkhead, choose your cable length and 1 PL259 connector fitted from the options list below. We will prepare your cable with the PL259 connected and prepare the other end of the cable for fitting. All you need to do after installing the cable is to screw on the 2nd PL259 and solder the tip (very important that it is soldered) – a length of low melting point solder is included in the aerial kit for this purpose. By the way, RG8X needs a 7mm hole.

If you don’t need this option select 2 PL259 connectors fitted from the list.

 

Glomex RA111AIS TECHNICAL SPECIFICATIONS

FREQUENCY RANGE 161,975 – 162,025 MHz
GAIN AVERAGE 1 dB
IMPEDANCE 50 ohms
POLARIZATION Vertical
SWR ≤ 1,2 at 162 MHz
MAX INPUT POWER 50 W
DC GROUND No
ANTENNA LENGHT 140mm/5”
ANTENNA WEIGHT 220g/7,76oz
TERMINATION SO239 for PL259 male connector

Just a note regarding gain of an aerial. An aerial cannot amplify the RF signal in the same way that an audio amplifier will make a small sound much larger. Gain in an aerial refers to how directional it is. An aerial can be made to be more or less directional and if you know where your signal is coming from then a very high gain aerial pointed in that direction will be the best choice but it will be very much less efficient in other directions. Where a signal may come from any direction it follows that low gain aerial (less directional) aerial will be better. As an example of how this works in reality: your TV aerial will be very high  gain as it points to a specific TV transmitter that doesn’t move whereas your mobile phone aerial must receive signals from all directions so will be low gain.

There are lots of explanations for aerial/antenna gain on the internet and some get very complicated but the link below has quite a good explanation for anyone interested.

Click this link     (antenna-theory.com)

 

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