I never noticed that on either of mine but just walked out to the garage and sure enough - they have it. Of course neither of mine have the factory nav option. My company was nice enough to get me the HP GPS unit for my PDA and I throw the receiver right up on the dash. It's a POS too but every now and then I need to find an address and it sooner or later gets me there. It actually has the same Navteq software in it.

 

For the FM Its in the same place... In front of the passenger door... non telescopic.

 

It could be.... I don't remember my electromagnetics well but I believe the antenna length has to be related to the wavelength of the signal.... since the frequencies are so different... the antennas will be as well.

Most GPS antennas I've seen are "patch" types (ie they are basically a flat rectangle with the antenna etched like a circuit board). They are usually powered with an amplifier on the antenna. I've seen one GPS antenna that looked sort of like a cell phone stub. When we tore it apart the actual antenna was a tight helix of metal coiled around the stub.

In short (since I seem to have babbled) the physical configurations of GPS and FM/AM antennas are pretty different and it would probably be very difficult to integrate them and get good reception.

 

OK, I figured it out.

As you know, GPS signals are weak and can be blocked easily. Whenever we drive into our basement garage, the heading indicator turns red indicating the loss of GPS reception.

First, I tested a metal clipboard by holding it over our handheld GPS unit. It blocked all overhead reception.

I put the metal clipboard over the square on the dashboard. The square does look like a patch antenna. It is not. GPS reception stayed green.

Next I tested aluminum foil by wrapping a single layer around our handheld GPS. It blocked all reception.

I wrapped the AM/FM radio antenna with 3+ layers of aluminum foil. The antenna does have an unusual spiral, but it is not the GPS antenna. GPS reception stayed green.

Then I put a single layer of foil over the top of the windshield. Some cars do have antennas embedded in their windshields, but I guess this is just a defroster. GPS reception stayed green.

I was stumped and was just playing around with foil on top of the dash when I noticed the heading indicator occasionally turning yellow. When I put a single layer of foil over the unit (but leaving the little square uncovered) and used another single layer of foil to form a hood over the LCD display, GPS reception immediately turned yellow and then went red. The GPS antenna is either in or on top off the Visteon Navigation Radio.

This isn't a great place for the antenna because the roof blocks a good portion of the sky. However, it does seem to do a decent job and it can apparently receive at angles you might not expect (like through the side windows). If the reception isn't good enough, the obvious solution would be to get a GPS reradiating antenna and put the external antenna on the roof and the reradiator on the dash on top of the navigation radio.

Now I better put the big ball of foil in the recycling bin before my wife sees how much aluminum foil I used in my experiments...

Lloyd

 

So, if one wants good GPS reception, one really needs the sunroof option too?

 

My handheld uses a reradiating (Bluetooth) antenna. It's about 3"x2"x1" thick. I usually throw it up on the dash but on winding roads it slides all over the place and eventually ends up on the floor (too lazy to add velcro). Quite often I'll just drop it into a cup holder and surprisingly it holds the signal as well as when it is on the dash.

A roll of Reynolds wrap sacrificed for a good cause.

For a full wavelength antenna at such high frequencies, the antenna would only need to be 6-7" in length so a very short piece of wire is all that is needed. Coil it up and there is nothing to it.

Some of the GPS antennas are a double dipole antenna - two inverted vees at 90° angle to each other. Gotta pull out my radio school books to see what the benefit of that would be - maybe allow more omnidirectional reception.

 

The GPS antenna on my 2006 FEH with the NAV setup is simply underneath the dash behind the head unit. The dashboard appears to be semi-transparent to GPS signals. I also have placed a second GPS antenna underneath the dash in the same location for use in APRS operation.

Hope this helps!

 

Thanks, that is consistent with the results of my experiments.

GaryG also said it was behind the unit, but I thought he meant it was the little square.

I guess I'll pull the unit myself and take a look at it one of these days. I'm planning to install one of those switches so the passenger can enter destinations while moving.

Lloyd

 

It is the little square that is attached to the piece of angle iron behind the head unit. Seperate from the large head unit itself.

 

When people were talking about a little square in this thread, they were talking about a little recessed square on the dashboard next to the windshield. I don't know what it is, but it's not the antenna.

Just to make sure no one is confused, you must be talking about a different little square, which is the real GPS antenna that is mounted out of sight underneath the dash behind the unit. Sounds like a patch antenna.

Lloyd