If this is a 72Mhz radio then another great option is a smiley antenna. I've used these antenna's for years and have never, ever had an issue. The best price I've found is at Dymond Modelsport. It's on page 10 of their catalog:
http://rc-dymond.com/DymondCatalog.pdf
Their website is here:
http://www.rc-dymond.com/
Curtis
Montana