Hi Eric,
Quote "As we all know the round ones are slightly better than useless. Why do caravan manufacturers still keep installing them is beyond me."
Because it ticks one box for the new owner - does this make of caravan have a TV aerial?
The UK caravan market is driven by cosmetic features, such as: easily discernible new model graphics (I have the 2008 model one-upmanship) - colour of interior - carpets - curved foam seating that doesn't make a great bed - and so on.
Just take a look through a series of brochures - and notice the new "features" for each model year - and now apply your experience as a caravanner to these features.
This is a standard technique in professional selling - giving people a long list of things to tick off to help them make the purchase decision, and these must be things that either look good in the showroom or are a "this van has that too" feature so the van is not excluded.
This approach sells vans in the UK market, rather than any hidden improvements to quality - like improved build quality, sensible nose-weights, improved stability. But that's probably only something you look for after a few "unhappy" purchases.
To be fair, the mushrooms do work in strong signal areas where there is little multi-path distortion too - so yes you do have a functioning aerial. And them you can buy the real one as an accessory purchase later on.
Robert