  An alternating gradient electric guide provides a way to transport a wide
variety of polar molecules, including those in high-field seeking states. We
investigate the motion of polar molecules in such a guide by measuring the
transmission of CaF molecules in their high-field seeking ground state, with
the guide operating at a variety of switching frequencies and voltages. We
model the guide using analytical and numerical techniques and compare the
predictions of these models to the experimental results and to one another. The
analytical results are approximate, but provide simple and useful estimates for
the maximum phase-space acceptance of the guide and for the switching frequency
required. The numerical methods provide more accurate results over the full
range of switching frequencies. Our investigation shows that, even when the
fields are static, some high-field seeking molecules are able to pass through
the guide on metastable trajectories. We show that the maximum possible
transmission requires accurate alignment within the guide and between the guide
and detector.
