Circularly Polarized High Gain Coaxial Line Leaky Wave Antenna With Backfire Radiation

This communication presents a leaky wave antenna based on a standard rigid coaxial cable showing circular polarization (CP) in the backfire direction. Here, CP is achieved by using a sequential rotation scheme. Periodic slots are cut on the outer conductor of the cable leading to radiation from the n = -1th fast space harmonic. The circular geometry of the coaxial limbic allows to easily obtain space quadrature by rotating the successive slots by 90 degrees about the cable axis. The required time quadrature for CP is obtained by slot-to-slot separation along the propagation direction. The antenna is designed and fabricated for X-band applications using a low-cost coaxial cable and is excited using a standard SMA connector. The measured gain is 20.26 dBic with 3 dB beamwidth of 14 degrees at 10.26 GHz. The measured axial ratio of the left-handed CP antenna is below 1.8 dB in the backfire direction.

Automated summary

This paper presents a leaky wave antenna based on a standard rigid coaxial cable, which exhibits circular polarization in the backfire direction. The antenna achieves circular polarization by using a sequential rotation scheme and periodic slots cut on the outer conductor of the cable. Both space and time quadrature required for circular polarization are obtained through rotation and separation of the slots along the propagation direction.