CPW-Fed Circular Disc Monopole Antenna with Defected Waveguide Structures

This paper presented a parametric study on coplanar waveguide-fed (CPW-fed) circular disc monopole antenna with defected waveguide structure (DWS). The CPWfed circular disc monopole antenna was designed to cover wideband frequencies. Afterward, the monopole antenna was attached to a waveguide with a uniplanar compact defected waveguide structure (UC DWS). The simulation design and parametric studies were done by using the CST Microwave studio software. Initially, the CPW-fed circular disc monopole antenna was designed to achieve return loss of -10dB from 2.36GHz to 10GHz. The directivity has improved significantly when the monopole antenna was attached to a waveguide where the highest directivity was 9.83dBi at 8.5GHz. However, narrower bandwidth and lower efficiency were achieved. It achieved a bandwidth of 0.49GHz and highest efficiency of -1.76dB at 8.5GHz. The UC DWS was then designed on the inner surface of the waveguide with smaller dimension with 6.25 x 6.25mm 2 and a small gap of 0.3mm. The directivity and gain have been improved. The highest directivity and gain were 7.10dBi at 8.5GHz and 5.42dB at 6.5GHz respectively. The bandwidth was 3.66GHz where it covered from 6.34GHz to 10GHz

Microstrip-Fed Circular Disc Monopole Antenna with Defected Waveguide Structure

This paper presented the microstrip-fed circular disc monopole antenna with defected waveguide structure. First, the microstrip-fed circular disc monopole antenna was designed. Next, the monopole antenna was designed with waveguide and lastly followed by the defected waveguide structure where the uniplanar compact (UC) structure was used. CST Microwave studio software was used for simulation and parametric studies process. Initially, the microstrip-fed circular disc monopole antenna was designed to achieve return loss less than -10dB for wideband frequencies. Then, the gain and directivity was improved with the integration of waveguide. The highest directivity of 11.38dBi found at 13.5GHz. However, low efficiency and narrower bandwidth were obtained. Next, uniplanar compact defected waveguide structure (UC DWS) was designed at inner surface of waveguide. The bandwidth achieved 3.09GHz where it covered from 10.91GHz to 14GHz. Meanwhile, the directivity maintained higher than the monopole antenna with highest directivity of 8.84dBi at 10GHz. The gain was also improved from 11GHz to 14GHz with highest gain of 6.38dB occurred at 13.5GHz