high resonance reduction for broadband patch antenna

recently i'm busy with a patch antenna working at around 2.3GHz. A slot on the patch is used to provide two adjacent resonant frequencies to enhance the bandwidth and a L probe feeding technique is applied to ensure good impedance matching.
However, i found one of two resonances is so strong that could hardly be of any use in bandwidth enhancement and the other is alway keeping a fairly smooth shape. Pls see below:

could someone kindly give me some advice on how to lower the resonance, equivalently lower the Q value, while the 3 dimensional volume of the antenna cannot afford to be further expanded any more.
Thank you for your concern and any comment is welcome![/img]

wt is u r er value & height?