Ok, I have a question for an antenna expert. I'm a UCF student
designing a UHF RFID system for a new kind of robot positioning system,
and I have two choices to make:

1. Circular vs. Linear polarized antenna for the RFID reader
2. Halfwave dipole vs. Fullwave loop antenna for the tags

The reader antenna transmits a signal that electrically couples the tag
antenna, inducing a current that the tag uses to transmit its ID number
back to the reader. It's a long range application, so it's important
that I maximize the power transfer to the tag. Here's my current
understanding of the matter, let me know if I'm wrong:

A L-pol reader antenna with a dipole tag antenna will get great power
transfer, but there will be lots of null zones if the tag is oriented
improperly.

A C-pol reader antenna with a dipole tag antenna will get great
orientation indifference, but power transfer to the tag will suffer.

A L-pol reader antenna with a loop tag antenna will also get great
orientation indifference, but sub-optimal power transfer.

A C-pol reader antenna with a loop tag antenna will get both great
orientation indifference and maximum power transfer.

So I believe I want to do the last one, but I wanted to get some input
from people with antenna experience, in case I have no idea what I'm
doing, which is entirely plausible.
Thanks!
Nathaniel