Square flat "dishes" are very much high-tech and in vogue actually. They are manufactured and sold for normal satellite reception. See here for example: http://www.satalogue.com/section4/page0.htm
I'm not sure though what kind of (built-in) LNB and polarisor your particular squarial has. That may be a restricting factor. Is it a BSB squarial? The original BSB DMAC broadcasts were right-hand circularly polarised, so the squarials' LNBs presumably incorporated a dielectric depolarisor. See http://www.staddiscombe.freeserve.co.uk/bsb.html
I guess to convert it to work as a normal univeral LNB you'd need to remove that and "twist" the dish by 45 degrees so the H/V probes are aligned with the incoming non-depolarised H/V signals.
The real limiting factor will inevitably be the extremely small size of the dish. And although voltage-switching is used for H/V selection (a la universal LN
it probably isn't capable of receiving over the extended frequency range (switching hi/lo using the 22khz signals)
But I'm guessing and expect to be corrected...
2old