  This paper proposes a dual-band frequency scanning meandering microstrip
leaky-wave antenna with linear polarization in the Ku-band and circular
polarization in the K-band. This is achieved by making use of two spatial
harmonics for radiation. The unit cell of the periodic microstrip antenna
contains three meanders with mitred corners. To ensure circular polarization, a
theoretical formulation is developed taking into account the delay caused by
microstrip length intervals. It defines the unit cell geometry by determining
the length of the meanders to ensure that axial ratio remains below 3 dB
throughout the operational band. Moreover, the meanders are used to provide
better control over scanning rate (the ratio of change of angle of maximum
radiation with frequency) and reduce spurious radiation of harmonics by
ensuring single harmonic operation within the operational band. To guarantee
continuous scanning through broadside direction, open stopband is suppressed
using mitered angles. The antenna is designed on a 0.254-mm substrate making it
suitable for conformal applications. The fabricated antenna shows a backward to
forward beam steering range of 72 deg (-42 deg to 30 deg) in the K-band
(19.4-27.5 GHz) with circular polarization and of 75 deg (-15 deg to 60 deg) in
the Ku-band (11-15.5 GHz) with linear polarization.
