Antenna Review (GPS-RRAD-45)
Please Note: OFCOM have ruled that re-radiating antennas are illegal and so these can no longer be purchased nor used in the UK.
One of the must have GPS Accessories for anyone
looking to use a GPS Receiver in-car is a re-radiating antenna. A
re-radiating antenna re-radiates the GPS signal from outside the car
to inside the car. If you have a vehicle which has a coated windscreen to
keep the heat or sun out, or a windscreen with a heater element coil in it
allowing you to defrost the windscreen quicker in those winter months, then this
may reek havoc with the GPS signals trying to come through the windscreen to
your GPS receiver.
Re-radiating antennas aren't that expensive.
They start at around £45, and although they don't look much, they do the job
well. All re-radiating antennas need to be powered, so most will come with
a cigarette/accessory plug. All you simply do is plug this into your
cigarette/accessory socket, place the GPS style mouse somewhere external on the
car, eg roof, bonnet, somewhere it will get maximum exposure (eg not a side wing
of a car), and then you just feed the cable inside the car, attach the sticky
back square somewhere in the car about 45cm away from your GPS receiver (the
sticky back square has Velcro on one side), and then fix
the antenna which has a Velcro square to this. Simple installation, better
signal, no drilling of a dash board, perfect!
Re-Radiating antenna with Velcro square
Re-Radiating antenna receiver
Re-Radiating antenna power plug
I think I have a coated windscreen, do I need a
Re-Radiating antenna ?
a question we are receiving a lot of. People with 4 or 5 sat signals on
average knowing there are a maximum of 12 satellites they can pick up think they
may be having problems. The easiest way to test this is, acquire a fix
in-car like you normally would do, then move the GPS receiver out of the car
onto the roof. Now see if your GPS signal increases by 2-5 satellites.
If it does, then you may be better off having a re-radiating antenna in-car.
Are re-radiating antenna's any good for in-car use
One of our readers Tim Buxton, decided after receiving poor
signals on his Navman GPS 3000 that he would do something about it, and
purchased a re-radiating antenna.
first decided to install this in his Fiat Scudo van which doesn't have a coated
heat resistant windscreen, or a heater coil installed.
decided to take some screenshots of the GPS Status screens from both TomTom
Navigator and Navman SmartST Pro. The screenshots in fig 1 and
fig 2 are from Tim's Fiat Scudo Van.
can see, these satellite locks are between 4 and 6, which is what you would
expect from a GPS receiver in a standard vehicle.
then took some screenshots with his newly purchased re-radiating antenna which
he purchased from GPS Warehouse, and the screenshots are show in fig 3
and fig 4.
can see, there's a vast improvement on signal. The signal locks have now
gone from 6 locks to 9 under TomTom Navigator and from 4 to 9 on Navman's
really does demonstrate how the re-radiating antennas operate, and how much
signal can be gained from purchasing one of these and installing them in your
then decided to install the re-radiating antenna into his Renault Scenic which
does have a reflective screen, and again the signals have increased.
satellite lock has now gone from 2 on TomTom Navigator and 3 on Navman SmartST
Pro, to 7 on TomTom navigator and 6 on SmartST Pro.
admit I was amazed at the signal strength difference. Personally with my
Navman I'll receive around a 5 on an average day, to around 9 on a good day.
re-radiating antenna that Tim purchased from GPS Warehouse is the
GPS-RRAD-45 which costs £44.99 inc VAT.
Please note, even if you are
receiving a 4-5 satellite 3D lock, you may not experience any greater
signals. First test by moving your GPS receiver out of the car
to see if your signal increases. If it doesn't, then purchasing
a re-radiating antenna will probably not do much for your signal.
If you are looking for a cableless setup and would
prefer a battery operated re-radiating antenna, then check out the
Battery Re-Radiating Antenna Review.