Welcome to the RR forums If you're monitoring Cook Co. Simulcast (ARMER) & the stock antenna isn't bringing you good results then you're likely experiencing simulcast distortion due to being within monitoring range of two or more simulcast cells. An antenna upgrade will most likely make the issue worse. There are a number of multipath mitigation methods in the wiki I linked but they work in very few cases. Ultimately you'd be much better off with an SDS100 or SDS200 to monitor simulcast systems