QUESTION

Question

Hi,

We were using the antenna SR4G053 (with the eval board) in horizontal position and things were looked good. The reference ground plane is parallel to earth's surface and donut is actually vertical.

When we tried to use the antenna in a vertical position, the performance was very bad (relative to a dipole). Basically the donut is now horizontal with the null pointed towards the sky (similar to a dipole antenna pattern). Can you please help us in case we are missing anything? Since the eval. board's ground plane is now perpendicular to earth's reference plane, does it impact anything negatively?

Thanks very much!

-Pradeep

Answer 1

Hello Pradeep,

What you are seeing is typical for GPS antennas with a dipole radiation pattern. Since the SR4G053 will only receive the satellites at the horizon when the evaluation board is placed vertically there will be more interference of the signal from the satellites due to many things that exist along the horizon with some being vegetation, buildings and refraction due to the atmosphere. When the antenna is placed parallel to the earth it is able to receive the signals from the satellites directly above it so there as significantly less interference between the satellite and our SR4G053 antenna.
Please also be aware of what you are setting the evaluation board on because if you are using something that will make the ground plane look longer you will shift the frequency of the antenna and it will not perform as desired. Plastic and Styrofoam are two good mediums to use two place the antenna on or hold it up vertically without loading the ground plane to make if look longer to the antenna and therefore shifting the antenna's resonant frequency.
Best regards,

Geoff S.