...feed.¹

The generic IF-channel labels $\sf p$ and $\sf q$ are known as X and Y for WSRT and ATCA, and R and L for the VLA. They should not be confused with the two receptors $\sf a$ and $\sf b$, since the signal in an IF-channel may be a linear combination of the receptor signals.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... product'²

Also called the outer matrix product, or tensor product, or Kronecker product. See [2].

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... write:³

In one influential book [12], the factor 0.5 is omitted from $\sf S^{\odot}_{}$. This is clearly incorrect, since a single receptor can never measure more than one half of the total flux of an unpolarised source.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

...with⁴

One might argue that a more consistent form of $\cal {H}$ would be an expression in terms of the $\pm$$\pi$/4 ellipticities that are intrinsic to a circular receptor:

$$\cal {H} \sf Ell \pi \pi {\frac{1}{\sqrt{2}}} \left(\vphantom{\begin{array}{cc}1 & i\\ i & 1 \end{array}}\right. \begin{array}{cc}1 & i\\ i & 1 \end{array} \left.\vphantom{\begin{array}{cc}1 & i\\ i & 1 \end{array}}\right) \left(\vphantom{\begin{array}{cc}1 & 0\\ 0 & i \end{array}}\right. \begin{array}{cc}1 & 0\\ 0 & i \end{array} \left.\vphantom{\begin{array}{cc}1 & 0\\ 0 & i \end{array}}\right) \cal {H}$$ (17)

However, a choice for a different $\cal {H}$ should not be made lightly, since it would affect the deeply entrenched form of the Stokes matrices.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.