study, rather we use the true baseline distribution as obtained from the antenna positions. The minimum and maximum baseline for the SKA1-low at redshift 15 turn out to be $\sim 8.5$ and $\sim 19500$ respectively.

The primary field of view (FOV), which depends on the diameter of the individual antenna and observing frequency, is $\sim 5.5^{\circ}$ for the SKA1-low at redshift $z=15$. The maximum angular size ($\theta_{\rm max}$) that can be sampled in the image depends on the minimum baseline considered for the analysis, although the image can be made over the full primary beam. For example, if the minimum baseline $U_{\rm min} \sim 8.5$, then the maximum angular scale $\theta_{\rm max}$ that can be sampled is $6.7^{\circ}$ (which corresponds to a length scale of $1230$ comoving Mpc at redshift $15$). On the other hand, the angular resolution ($\Delta \theta$) of the image depends on the longest baseline considered for the analysis. For example, the SKA1-low should be able to produce images with highest resolution $0.175$as its longest baseline is around $U_{\rm max} \sim 19500$  at redshift 15. However, the system noise will be much stronger compared to [H [i ]{}]{} 21-cm signal if the image is made at this 