[KaBar67]

Does anyone know if the Sirius radio antenna can be used for CB or HAM radio in a car? It's just sitting there pointed up.....

 

[mongo]

In a word, no.

Satellite radio is in the gigahertz range, far above CB and ham frequencies.
http://www.tech-faq.com/satellite-radio.shtml

 

[vegasrandall]

for ham/cb antenna check the amateur radio supply catalog.
the length of a antenna is inversly proportional to the frequency.higher the freq.the shorter the antenna

 

[KF4LNE]

With a lot of modification the Sirius antenna can be used for the 2.4GHz amateur band and maybe even the 1.2 GHz band. To get this to work you must first remove all of the active components from the antenna. Your best use for an unused satellite radio antenna is for GPS reception since it is very close to the frequency range used by GPS. If you are looking for a low profile antenna consider looking for a railroad locomotive antenna or one of the PCTEL low profile antennas. They can be found for the VHF-HI, UHF and 800/900MHz bands.
http://www.maxrad.com/catalog_group_detail.cgi?id_num=22