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<span>This article presents an analysis of reflection loss and reflection phase behavior of a novel microstrip reflectarray antenna, embedded on paper substrate material. Two different paper substrates were first analyzed for dielectric material properties. A detailed analysis of scattering parameters of rectangular patch element with variable substrate heights has been carried out. Rectangular patch elements fabricated using adhesive copper tape over the paper substrate, show that a wide bandwidth is achieved compared to available conventional substrate materials. Fabricated patch elements over paper substrate material show a broadband frequency response of 340 and 290 MHz. It has also been demonstrated that the measured reflection phase ranges for both the substrate cover 310º and 294º at low phase gradients of 0.12 and 0.24 º/MHz respectively.</span>

Significant improvements in terms of bandwidth of reflectarray antennas have been achieved by introduction of innovative paper substrate dielectric materials. Three differently custom composed organic dielectric substrates have been characterized for dielectric properties using a broadband technique based on open ended coax cable method. The substrates show low dielectric permittivities of 1.81, 1.63 and 1.84 along with a loss tangent of 0.053, 0.047 and 0.057. Validation of using the proposed substrates for reflectarray antenna was done by modelling and fabricating reflectarray unit elements on the three substrates. Scattering parameter analysis of unit reflectarray elements show encouraging results with a broadband frequency response of 340 MHz at a phase gradient of 0.14º/MHz. Thus the proposed substrate could serve exceptionally to address the narrow bandwidth problem in reflectarray antennas.

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Abstract. This paper deals with the design, fabrication and performance evaluation of a dual C slot compact reflectarray element. It has been demonstrated that the progressive phase distribution of array elements can be achieved by minor variation of C slot widths, without changing the entire patch dimensions. A comparison between measured and simulated results confirms wider phase range coverage of 340 o and a 10% bandwidth of 70 MHz have been achieved. A good comparison between simulated and measured results has been exhibited by comparing three different slot widths of the proposed design. IntroductionReflectarray antennas are a moderate choice between the bulky parabolic dish reflectors and expensive phased array antennas. They have proved their significance as effective antennas in radar systems and long range communications. Reflectarrays were introduced in 1963 as a bulky waveguide structure, fed by a distant spatial source [1]. The potential of reflectarray was not gauged well at that time but the with the advent of printed circuit board (PCB) technology, new design schemes have been presented combining the prime features of parabolic dish reflectors and phased array antennas. Today's reflectarray antenna consists of a planar surface with printed array of radiating elements, illuminated by a feed source. The phases of elements are controlled in such a way to form a planar wavefront at far field distance from array [2]. Different design schemes for the reflectarray unit cells have been presented in the literature to control the phase distribution of individual elements on the periodic reflectarray antenna. Recent techniques for phase distribution include stub loaded microstrip elements, elements of variable sizes and embedded slot configuration in rectangular patches [3][4][5]. It has also been demonstrated that different ring shaped elements such as the circular spit ring, concentric split ring square and split ring with variable rotation can also be used to control the phase behavior of the reflectarray elements [6][7][8]. However the phase range of the split ring element is observed to be compromised. Moreover the introduction of a gap in the structure greatly decreases the gradient of the phase curve and reducing the linear phase region of the phase curve. Thus, it is leading to phase errors in a periodic array.This work presents a novel X-band dual C slot reflectarray antenna. The proposed slot configuration offers a wider phase range coverage and bandwidth performance over the X-band frequency range. The phases of individual elements can be easily controlled by changing the width of embedded slot configuration, without any changes in the entire element size. The design was fabricated over Rogers Duroid 5880 substrate of 0.508 mm thickness. Waveguide simulator technique