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Demian Arancibia edited untitled.tex
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\section{Design Variables}
This section aims to include all relevant design parameters that might influence the selected performance objectives.
\subsection{Antenna Aspects}
\subsubsection{Antenna Effective Collecting \subsubsection{Collecting Area}
\subsubsection{Antenna Temperature}
\subsubsection{Antenna Pointing Accuracy} \subsubsection{Temperature}
\subsubsection{Efficiency}
\subsection{Pad Aspects}
\subsubsection{Quantity}
\subsubsection{Position}
\subsection{Receiver Aspects}
\subsubsection{Bandwidth}
\subsubsection{Reciever Temperature}
\subsubsection{Calibration Cost} \subsubsection{Temperature}
\subsubsection{Efficiency}
\subsection{Correlator Aspects}
\subsubsection{Position}
\subsubsection{Efficiency}
\section{Performance Objectives}
This section aims to include
all the array performance objectives that might be influenced by design choices.
\subsection{Minimize Brightness Sensitivity Limit}
It is often instructive to express the system temperature in terms of the System Equivalent Flux Density, $SEFD$, defined as the flux density of a source that would deliver the same amount of power (see \cite{sensitivity2}):
\begin{equation}\label{eq:system_equivalent_flux_density}
...
\end{equation}
where $T_{sys}$ is the system temperature including contributions from receiver noise, feed losses, spillover, atmospheric emission, galactic background and cosmic background, $k_B = 1.380 \times 10^{-23}$ Joule $K^{-1}$ is the Boltzmann constant, $A$ is the antenna collecting area (thus we could also write $\pi \cdot D^2$), and $\eta_a$ is the antenna efficiency with $\eta_a = \eta_{\text{surface efficiency}} \cdot \eta_{\text{aperture blockage}} \cdot \eta_{\text{feed spillover efficiency}} \cdot \eta_{\text{illumination taper efficiency}}$ (see \cite{antenna}).
If we assume
each aperture has N apertures with the same $SEFD$,
observes obserbing the same bandwidth $\Delta\nu$, during the same correlator accumulation time $\tau_{acc}$, then the weak-source limit in the sensitivity of a synthesis image of a single polarization is
\begin{equation}\label{eq:sens}
\Delta I_m = {\frac{1}{\eta_s
}}{\frac{SEFD}{\sqrt{2 }}{\frac{SEFD}{\sqrt{(N(N-1) \Delta \nu \tau_{acc}}}}
\end{equation}
in units of Janskys per synthesized beam area.
with $\eta_s$ most important factor being correlator efficiency $\eta_c = \frac{\text{correlator sensitivity}}{\text{sesitivity of a perfect analog correlator having the same } \tau_{acc}}$ (see \cite{sensitivity}).
Hence the
Thus if we are using
x, vector $x = {\text{antenna diameter}, \text{antenna efficiency}, \}$, the antenna diameter, as the optimization variable the problem we would like to solve is:
\begin{equation*}
\begin{aligned}
& \underset{x}{\text{minimize}}
...