Comparing GPS Antennas

I have tried several models, the original Trimble Bullet, the HP 58532A and several pucks, including a nice Trimble mag-mount unit. Two of the pucks are designed for marine use, with a decent waterproof case and mounting, but they are in an all plastic case. There have no part number that I could see, I need to look closer to see if there is a manufacturer's mark. They were obtained on eBay from a long forgotten vendor…

I am not sure how Trimble rates the mag-mount antenna, but it probably was not designed for permanent outdoor installation, even though it is heavy and looks very well made.

They were compared by plugging them into my main Thunderbolt receiver and checking the time to complete self-survey. Because of the constantly changing constellation, it is difficult to compare antennas otherwise over a short time. I felt the self-survey was a useful indicator even though I am perfectly aware it is just that. Self survey takes several hours (2 to 8 in my experience, depending on the combination of antenna and receiver).

It seems my main Thunderbolt receiver (original OEM design with built-in supply) is more sensitive than the two Group-buy Thunderbolts I also have, as it does complete self-survey faster and seems to report more satellites, even though I have not yet attempted to log that information over a period of time to give an objective result. Another project for the winter…. That could also be due to a different internal configuration of the receivers, even though I have not seen any difference in look-up angle settings and such.

All antennas were compared while inside the house, in the upstairs ham shack/office/lab, so pretty close under the shingles covered roof and facing south.

The Bullet I have is less sensitive than the others. I receive fewer satellites with it and it takes much longer for the self-survey to complete, I do not use it. I got it with my main Thunderbolt receiver and it was not new when I got it. All other antennas were bought new.

The HP and the pucks seems to give about the same signal strength and take about as long to complete the self survey. The HP will go outside when I have a chance to install it, it's still way too hot over here to do anything outside that you don't HAVE to do…

I bought the HP on eBay, new, for $50 with shipping, compared to about $25 each for the pucks, including shipping costs. Unless you are satisfied with an indoor antenna (in which case I would say: “What are you doing on time-nuts?”), I can't justify saving $25 by using a puck compared to the wonderful piece of design and technology that the HP 58532A is. By the pound, you get much more with the HP

Didier KO4BB

PS: Bugs have antennae, receivers and transmitters have antennas: http://en.wikipedia.org/wiki/Antenna