Microstrip patch antenna with defected ground structure for biomedical application

An operating center frequency of 2.45 GHz rectangular inset fed microstrip patch antenna with defected ground structures for ISM band applications has been presented in this paper. The return loss of the proposed antenna is -29.726 dB with impedance bandwidth for S11<; -10 dB is 2.441 to 2.462 GHz, that covers IEEE 802.11 g/n OFDM 20 MHz channel width. The antenna has a directional far-field pattern at the boresight direction of O' with a good total antenna efficiency of -1.39 dB. The proposed antenna is light weighted, easy to fabricate and achieved good directivity gain of 7.04 dBi and VSWR of 1.06 at the resonant frequency that makes it suitable for WLAN applications.

The physical flexibility has a significant impact on microstrip antenna design for wireless body area network (WBAN) application and designing such an antenna on a flexible substrate has many challenges. This paper presents an inset-fed microstrip patch antenna designed on a rubber substrate with defected ground structure (DGS). DGS is used to further enhance the antenna performances. The designed antenna is expected to operate at 2.45 GHz within the ISM band range and the return loss is −37.33dB with wide −10dB bandwidth of 101MHz. In addition, the VSWR value is 1.03 at the resonant frequency with an increase of 7.5% in the realized gain compares to the antenna without DGS. The accumulated surface current is 174 A/m on the radiating patch with a maximum realized gain of 3.42 dB and the maximum radiation efficiency of more than 60%. The antenna design, simulation, and performance analysis have been conducted using Computer Simulation Technology (CST) software. This paper focuses on the improvement in the return loss and antenna operating bandwidth of the flexible antenna to make it suitable for WBAN application.

This article presents a planar monopole antenna on flexible substrate for middle band 5G (3.5 GHz) application in Malaysia. The antenna has been designed and optimized for its gain and efficiency with an improved performance in contrast of flexible substrate-based other antennas. The antenna resonates at 3.53 GHz and it has a -10dB bandwidth of 545 MHz. The bending effects of this antenna on the S-parameter and gain have also been investigated. The antenna is able to suppress all the other frequency bands until 20 GHz. The designed antenna has been utilized with a newly designed rectifier to act as an rectenna at 3.5 GHz for RF energy harvesting applications. A reasonable amount of DC output voltage of 930 mV, and a Power Conversion Efficiency of 43.5% have been obtained while 0 dBm RF input power is delivered to the rectifier input terminal. Apart from the utilization as an energy harvester being connected with the proposed rectifier, the designed antenna on flexible substrate can also be employed to biomedical and sensor applications.

Recently lower frequency band 4.5−5.5 GHz is proposed by the ASEAN countries for 5G cellular application and therefore, it is essential of designing an ultra-wideband (UWB) antenna for the particular band-notched characteristics. In this article, a compact tuning fork shape ultra-wideband (UWB) patch antenna with a variable band-notched characteristic has been proposed for 5G cellular application. The UWB antenna has been achieved by using a tuning fork shape with a simple partial ground plane. A pair of ring shape slits (RSS) on the ground plane has been added to achieve the band-notched characteristic. The proposed antenna has achieved a large −10 dB bandwidth of 7.8 GHz (2.9−11 GHz) and the VSWR value is less than 2 for the entire bandwidth excepted for notched frequency bands of lower 5G bands (4.5−5.5 GHz). Moreover, the antenna has a peak radiation efficiency of more than 87% for UWB and less than 27% for the notched frequency band. The notched-band is shifted with the change in the position of RSS’s within the vertical axis and thus, the variable band-notched characteristics have been achieved. Besides, the proposed antenna is compact with the dimension of 45×34 mm2 that makes it suitable for the lower band of 5G application.