depends on where your permanent site is located relative to the available OTA TV transmit sites. in an urban environment just about any antenna should produce good results. farther out in the boonies you're gonna want something up as high as you can get it. TV is line of sight and since the switch to digital it's even more critical. and if there is anything between your antenna and the transmit point....a forest, mountains, tall buildings...you're gonna need the height. since your permanent why not get a residential style antenna, mount it on a piece of PVC and clamp it to whatever is handy?
but before I did any of that I'd replace the coax between your current antenna and the roof connector...probably a 3'-5' length. coax wears out over the years due to UV rays. it's a quick and cheap experiment. if that doesn't do the job I'd check to be sure the amp is doing it's job before I spent $ on a new antenna.
and btw, there is no such thing as a 'digital' or 'HD' antenna. ANY antenna engineered for TV reception will receive digital AND analog signals. the receiver in the TV set processes those signals and displays them accordingly. what is different these days is many-to-most of the OTA stations are now broadcasting in the UHF portion of the TV band. adding the Winegard Wingman to your existing antenna will help boost UHF signals to your TV. do some research on that.
good luck.