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GPS Antenna

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brodin

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I just got a GPS module (superstar). The annoying thing about it is the antenna. What is so special about a GPS antenna?

It has about 5cm of wire(too shoort). The guy who gave it to me said that it couldn't be longer without being amplified.

Can i make my own antenna for a GPS receiver that is more suitable for my project?
 
GPS is a high frequency operation. the higher the frequency, the shorter the antenna. the antenna is ther for a reason.

wut the guy probably meant by "amplifying" was to match the impedances. you may be right, that you could get better reception w/ a longer antenna (im not sure of the frequency of GPS, and therefore how long an ideal antenna would be) but it would be pretty hard for you to re-match the impedances.

BTW, wut is your project?
 
What is so special about a GPS antenna?

It is a patch type antenna made from double sided pcb, but with a high dielectric constant to enable the reduction in physical size of the antenna.

It has about 5cm of wire(too shoort). The guy who gave it to me said that it couldn't be longer without being amplified.

The signal level received from a GPS satellite is around -126dBm at 1575 MHz for a good signal. Many GPS antenna's will have a pre-amp in it to amplify the signal before more noise gets picked up in the cable from the antenna to the receiver.

Can i make my own antenna for a GPS receiver that is more suitable for my project?

You can try. **broken link removed**
Notice that the size is already much bigger than the commercial units using ceramic for the dielectric. This person attempted to get a smaller size by using air as a insulator between the two layers. The connection point of the coax is also very critical to get the correct impedance match.
 
I don't really need to get the antenna smaller. But the problem with it is that it requires quite much "free sight" to the sky. I don't know, maybe all GPS are the same. It does not work indoors. Not even inside(beside) the window. I have to be outside to use it. Is this common for all GPS receivers. Would it be possible to change this whith a better antenna?

As you can see, i am very new to GPS receivers :wink:
 
And by the way. How many sats is recomended to get a rather acurate result? I had 5-6 when i tested it today in the car with the antenna by the front window.
 
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