Figure 6c,g show the effects of r1. Decreasing r1 gives decreasing values for both the magnitude and phase. The minimum value of r1 has been restricted to 1 mm for ease of fabrication. The resonance frequency of the unit cell is essentially determined by r1. Smaller values of r1 lead to smaller elements with correspondingly higher resonance frequencies, creating a wider separation between the frequency band of interest and the element resonance frequency. The result from this wide separation is a smaller transmission phase variation with respect to the scan angle. The inter-element coupling is controlled by the values of r1.