Riyadh Khlf  Ahmed, 
    Study on Dual-Mode Microstrip Slotted Patch Filter Using Perturbation Element,
    Journal of Engineering and Applied Sciences,
    Volume 14,Issue 3,
    2019,
    Pages 744-749,
    ISSN 1816-949x,
    jeasci.2019.744.749,
    (https://makhillpublications.co/view-article.php?doi=jeasci.2019.744.749)
    Abstract: In this research article, an investigation on dual-mode microstrip bandpass filter has been given. It
discusses the effect of various dual-mode resonators used in the literature with diverse kinds of perturbation
elements on frequency response of microstrip filter. A new compacted microstrip bandpass filter using new
slotted dual-mode resonator has been simulated and analyzed. This filter hassimulated at 5.7 GHz with return
loss and insertion loss values of 1.69 and 10.31 dB. Also, this designed filter has perceptibly narrow fractional
bandwidth of 2.22% (127 MHz from its center frequency). Consequently, the modeled microstrip filter can be
practical and integrated within many communication schemes and devices.
    Keywords: Microstrip filter;slotted patch resonator;dual-mode principle;compactness;bandpass;frequency