A low-profile and broadband slot antenna with artificial magnetic conductor (AMC) surface is designed for X and Ku communications. Loaded with evolved C-shaped branches, the proposed coplanar waveguide (CPW)-fed slot antenna, which consists of two radiating slots, exhibits wide impedance frequency band performance. The presented AMC, the unit cell of which is made up of two central hexagonal circles with six rectangle branches, operates in a wide in-phase reflection frequency band ranging from 6.0 to 13.94 GHz (79.64%) at the reference plane 4 mm above the AMC surface. An AMC surface composed of 8×10 AMC unit cells is located under the slot antenna with a distance of approximately 0.107λ (λ denotes the free-space wavelength at 8.0 GHz), which improves the radiation and impedance match properties of the broadband slot antenna while maintaining low profile. A prototype of the proposed slot antenna with AMC surface is fabricated and measured. Measured results show that the composite antenna achieves a wide impedance bandwidth from 7.64 to 14.58 GHz (62.47%). The measured peak gain is up to 10.26 dBi, and the maximum cross-polarization level is -17.5 dB for both E and H planes. Good agreements between the measured and simulated results validate good performance of the presented slot antenna within the desired frequency band.
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