This paper presents the introduction of a miniaturised and enhanced horn antenna that is loaded with a linear or triangular planar array of Circular Spiral-Line Structures (CSLS). A CSLS array was placed inside the horn aperture in order to reduce the size of the suggested horn antenna.The antenna's resonance frequency when loaded with CSLS array is 6.3 GHz, and when it is not loaded, it is 8 GHz.The dimensions of the antenna aperture and axial length would be 150×138×103 mm3 if it were intended for 6.3 GHz.However, by loading the CSLS array, the 8 GHz antenna's dimensions are reduced to 90×57×130 mm3, and a shift in resonance frequency from 8 GHz to 6.3 GHz results in a 68.7% miniaturisation in size.With the CSLS array put into the suggested antenna, the antenna's Bandwidth Improvement percentage (BWI) increases to 8.7%, the Enhanced Return Loss Ratio (ERLR) increases to 26.2 , maximum power intenisity Umax= 1.8 W/Str., directivity D= 25.8 dB, gain G=24.6 dB, radiated power Pr=0.92 for one watt input power Pin and radition efficiency e0 reaches to 95% for the proposed horn loaded with CSLS arrays compared with the horn without arrays .The SLSM linear array was designed and manufactured with a Rogers of εr=10.2 and thickness of 0.635 mm.An introduction and analysis are given to the laboratory test and measurement for the CSLS linear array loaded in the WR90 rectangular waveguide.Finite Element Method (FEM) based, HFSS, is used for the design and analysis of the proposed structures.