Microwave components which exhibit these attributes play a crucial role in such modern systems. These specification requirements include low insertion loss (IL), sharp filter response, also known as high roll-off rate (ROR), compact size, high selectivity, high isolation between output ports, wide stopband response, high suppression factor (SF), simple structure and affordable manufacturing processes. In particular, passive microstrip devices such as filters and power dividers have critical specification requirements. In recent years, modern wireless communication systems have become increasingly important, and the demand for high-performance active and passive RF/Microwave components such as antennas 1, 2, 3, filters 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, power dividers 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, mixers 33 and multiplexers 34, 35, 36, 37, 38 has grown substantially. The WPD has been fabricated and tested and shows good agreement between simulated and measured results and the proposed design has desirable characteristics for LTE and GSM applications. The proposed WPD has a small size of 33.8 mm × 27 mm (0.42 λg × 0.33 λg), where λg is the guided wavelength at the operating frequency of 1.8 GHz. The proposed modified WPD has a wide 20 dB stopband (from 2.54 GHz to 13.48 GHz) and filters the second to seventh harmonics with attenuation levels of greater than 20 dB. According to the obtained results, the input return loss (| S 11|), output return loss (| S 22|), output insertion loss (| S 21|) and isolation (| S 32|) are better than 34.2 dB, 26.2 dB, 3.52 dB and 31.2 dB, respectively. A lowpass filter (LPF) structure is utilized in both branches of the power divider to provide harmonic suppression. In order to improve on the current state of the art, a modified microstrip WPD is proposed that exhibits a substantially improved stopband and high isolation. However, these WPDs can also exhibit poor out-of-band performance while requiring a large footprint. Conventional Wilkinson power dividers (WPDs) can provide acceptable performance close to the nominal center frequency.
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