Big Dish or Small Dish
18 or 24 inch dishes originally used for DBS are not useful for FTA reception. Too small and the LNBFs are for a completely different non-compatible system. The larger elliptical dishes for multiple DBS satellite reception are also not useful, because while larger left and right, they still only provide the effective gain of an 18 inch dish on any one satellite. At the very minimum you should consider a 75 cm/30 inch Ku-band antenna with linear Ku-band LNBF. The added gain and bad weather performance of an 85 to 90 cm dish is well worth the added cost.
Those interested in larger quantities of network feeds and international channels, especially with HD transmission, should consider C-band. It has many rewards with the sheer quantity of channels that make it worth investing in. If you have the budget as well as the space, think about it.
C-band is a different creature. Despite the claims of some hobbyists that have received a C-band signal using a 90 cm dish, the reality is that very few channels are strong enough to reliably receive them on antennas that small. A six-foot minimum dish is suggested for C-band, and only on the stronger signals of some satellites. Motorized operation should consider at least the 7.5 foot solid Paraclipse Hydro antenna, or the new 8.5 foot Patriot mesh antenna. C/Ku band is best done with solid antennas such as our Hydro line (available in 6 and 7.5 foot sizes), while full satellite arc reception should consider nothing smaller than the 8.5 foot mesh, but preferably the 10 foot model, to have a chance at reliably getting weaker signals in the MPEG-4, DVB- S2 format. The weakest of the weak may actually require the 12 foot model, but that will require the space and the added costs associated with a larger antenna installation. Those on a budget, or facing aesthetic concerns might consider the following scenario: get a medium sized C band antenna and one or more Ku-band antennas, and connect them together with DiSEqC switches.
Those considering the 7.5 foot Paraclipse Hydro will find that it rivals the 8.5 foot mesh antenna in C-band performance, and has the bonus of extremely reliable Ku-band reception. A C/Ku band feedhorn and LNBs can be considered. C/Ku band LNBFs are marginal on a dish of this size due to performance issues, but can be considered as a way to save money if you accept their limitations.
This author prefers a separate 8.5 or 10 foot mesh antenna on C-band, which gives the ability to hand pick a high stability LNB with an appropriate feed system, or use one of the better C-band LNBFs for seamless operation with a V-Box to move the dish, and interfaced with an MPEG-4 HD receiver such as the Manhattan RS-1933. Separate Ku-band dishes with LNBFs can easily be connected to this system via a 4 input DiSEqC switch.
Commercial installations and quality conscious consumers should consider solid antennas for higher performance over a long term basis, especially when new weaker MPEG-4 signals are part of the picture. Hand picked electronic components such as PLL or high stability LNBs will enhance your ability to have a trouble-free installation.