How do you replace the radio antenna?

Hi all.... Back in Spring I had the frame in my 2003 Tacoma replaced by the dealer. All in all, the dealer did a great job and I've been quite happy with the results. The only gripe I have is during the frame replacement process something happened to my radio antenna. The reception in my radio is horrible now. I've checked and made sure the connection is secure behind the radio, so my hunch is the issue is at the antenna base. Does anyone have instructions (how to) remove the antenna? I know the only way to get to it is to go up through the back of the fender area, but how do you loosen the antenna from the fender? Do I need a special tool to loosen the antenna at the mast? Any recommendations on a better, more sensitive antenna to replace the factory one? I need something for better reception and maybe more sturdy to run through car washes.
I appreciate if anyone can help with this.

 

Not sure if the antennas have changed, my 98 had a "nut" at the base of the antenna, the Haynes manual suggests using snap ring pliers to remove this nut, mine was stuck/rusted/corroded and broke off, so I destroyed my friggin base trying to remove it... Next time i'll try soaking it in WD40 first