Spiral antennas are the flat cousin of helical antennas.  These antennas are usually constructed for use in wideband applications, such as UWB radars and communication links.  Being planar, these antennas are suitable for low profile applications and are readily manufactured using standard PCB techniques.    We have produced antennas of this type up to Ku band.   Let us work with you on your custom low profile, wideband antenna design.