A very compact Multiple-Input-Multiple-Output (MIMO) radiator providing dual notches is presented in this paper. It comprises circular ring monopoles fed by a microstrip line embedded with a slot of inverted U-shape. By etching a crescent slot, a split ring resonator slot, a circular slot in the circular monopole, a reversed U-shaped slot inserted along the feeding line, two notches are attained. It operates from 3.5 GHz to 12 GHz that overcomes interference from the Wireless Local Area Network (WLAN) (5.15-5.85 GHz) and X-band (7-8.1 GHz). MIMO antenna has a very compacted dimension of 44 mm × 44 mm × 1.6 mm at the lowest operating frequency and hence is suitable for portable devices. It has dimensions of 0.51λ × 0.51λ × 0.018λ where λ is the wavelength of the lowest operating frequency 3.5 GHz.

A dual-band operating patch antenna was designed and presented for C and X band applications at a resonated frequency of 5.9 GHz and 8.8 GHz by using Defected Ground Structures (DGS). The antenna is a modified quadrangular shaped patch that has 4 U-shaped slots and 1 I-shaped slot. It has H-shaped DGS. It gives 10 dB impedance bandwidth with 140 MHz operating in 5.85-6 GHz and 10 dB impedance bandwidth with 1.21 GHz operating in 7.87-9 GHz [1]. Rectangular patch antenna achieved dual-band operating at 6 and 9 GHz that find applications intended for satellite communication & radio navigation at small power levels and good bidirectional radiation pattern. It is appropriate for incorporation into portable devices [2]. A Novel printed monopole antenna consisting of the radiator of square shape with a couple of slots is fed by a coplanar waveguide (CPW). Intended to have double band operation, the slots are positioned lateral to the patch; added resonances are observed leading to a wider bandwidth. Also achieved radiation pattern with realistic at the operated bands [3]. A novel Gemini-shaped patch antenna with dual-band features was proposed for applications of C and X band at a resonated frequency of 6.53 GHz and 8.62 GHz. And also observed good impedance matching and high gain performance [4]. A wideband antenna operating in C & X bands that has impedance bandwidth of 400 MHz at 7.47 GHz, 790 MHz at 11.01 GHz. It is also observed as of small size, has high gain [5]. A simple single-layer antenna with a T-shaped radiator is designed to improve cross-polarization suppression of the antenna [6]. A novel antenna operating at multiple bands from 1.5 to 6 GHz is presented for IOT applications [7]. A key-shaped patch antenna exhibited a wide band that operates at frequencies intended for applications over C/X bands. It has a rectangular-shaped