Realizing that this is an OLD POST, maybe some won't see it, but we'll give it a whirl anyway.
I'm full-timing it in a 36' Monaco diesel pusher and have been pursing antenna alternatives to use with the Icom series of transceivers, like the 756PRO and the 706MKIIG.
The Shakespeare 28' antenna (Model 5300) looks to be SUPERIOR to all of those short coil-loaded antennas, where the RF gathers... but doesn't really escape/couple to the ionosphere.
I recently bought a NOS-NIB Hustler 4BTV from Craigslist and have thought about placing it on the roof of the coach with a foldover arrangement. BUT, since I also have an Icom AH-4 Antenna Tuner... this 28' Shakespeare might just be the ticket, or its shorter cousin, the 23' Shakespeare Model 393.
The Icom AH-4 tuner requires at least a 23' antenna, so the Shakespeare Model 393 just barely makes the grade. The Model 5300 betters the grade.
The 28' Shakespeare Model 5300 is available for $371, which is about the same you'd pay for one of those shorty, RF loaded Screwdriver type antennas, that surly won't deliver the performance that the Shakespeare will, provided the proper grounding *(counterpoise) is provided. On a motorhome coach, if the shielded side of the coax is grounded to the motorhome's frame, plus a ground rod, near the rear bumper of the coach, one should be in business, since the framing of the coach will serve as an excellent counterpose. And I've seen the 23' Shakespeare antennas advertised on eBay for around $175 bucks... so that's STILL BETTER than those RF attenuated, coil-loaded "SHORTY'S".
So, before you sell the Shakespeare "short" for one of those RF attenuated SHORT screwdriver antennas, think again!
We'll let you know how this all turns out!