Active vs passive gain of a Symmetricom 58532A GPS antenna

[tverbeure]

I have a Symmetricom 58532A GPS antenna. The data sheet says the following:

Total gain: >30 dBi (38 dBi typical @ elevation angle 90°)

dBi is the gain compared to an isotropic passive antenna that radiates or received uniform from all directions. Since the 58532A is a disc shaped, active antenna, I assume that the 30 dBi has an active and a passive component?

There are multiple PCB variants of this antenna. One of them has an NE3508, an LNA with a gain of 14dB. There are also two 2SC5508 LNAs with a typical gain of 16dB each. When I add up everything, I get a total of 46dB, but since there's a narrow pass band filter, I assume that the passive components around these LNAs reduces the total gain? Any idea by how much?

I'm also trying to figure out the typical gain of a flat disc shaped antenna (the PCB), but I can't find any pointers for that either.

PCB image source: https://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20190314/7d9a0aa1/attachment.pdf