Re: [Paparazzi-devel] LEA-4T

[address@hidden]

This is a very strange question but I'll try to help.  The receiver uses a very 
tight SAW bandpass filter centered on 1575.42 MHz, meaning the 3dB pass range 
is very narrow, on the order of a few MHz.  From your very narrow 3MHz 
bandwidth, it sounds like you are trying to use a very small antenna, maybe 
8x8cm?

It's important to note that the center frequency of the antenna is effectively 
reduced by a larger ground plane or heavier radome.  So if your antenna is 
designed for a center frequency of 1580MHz on a 30cm ground plane, which it 
probably is, you must use some combination of increased ground plane size and 
radome material to lower the frequency to 1575MHz.  Furthermore, a small 
antenna will be much more sensitive to detuning by nearby objects.

If you are looking for the smallest/lightest possible antenna that will still 
have a wide bandwidth and good resistance to detuning from nearby objects and 
ground plane issues consider the Sarantel helical antennas.  Anything smaller 
such as the little microchip antennas are really only suitable for approximate 
positioning of very slow moving objects and will not produce enough accuracy or 
reliability for autonomous activity.


-- address@hidden wrote:

Dear Paparazzi
I am working on formation flyin project at university of Southampton, UK. I
am using LEA-4T GPS receiverss as navigation sensors. I have stuck at a
point.
The bandwidth of my GPS receiver's antenna is 3MHz around L1 frequency, what
is the input frequency bandwidth for LEA-4T receivers. Is it same as 3MHz.
Your help in this regard will be a great hel at this stage.

Looking forward

Riaz Ahmed
PhD Student
Tizard Building
University of Southampton
So17 1BJ
UK










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