A triple-band planar antenna with a compact radiator is proposed for 2.3/3.5/5.5 GHz WiMAX and 5.2/5.8 GHz WLAN applications simultaneously. The proposed antenna consists of an inverted-L (IL)-shaped radiating element and a parasitic element in the ground plane to generate three resonant modes for triple-band operations. Each of the three resonant bands can be tuned separately to cover other wireless applications also. Owing to the coupling of the IL-driven element and the parasitic element, a compact radiator of 10 × 17.3 mm 2 is realised for triple-band operations. Some key parameters affecting the antenna performance have been analysed using computer simulations. To validate the simulation results, the prototypes of the proposed antenna are fabricated on an inexpensive FR-4 substrate and tested. Good radiation characteristics of the proposed antenna have been obtained. The simulated and measured results are in good agreement.

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A compact, low-profile, coplanar waveguide (CPW)-fed quad-port multiple-input–multiple-output (MIMO)/diversity antenna with triple band-notched (Wi-MAX, WLAN, and X-band) characteristics is proposed for super-wideband (SWB) applications. The proposed design contains four similar truncated–semi-elliptical–self-complementary (TSESC) radiating patches, which are excited through tapered CPW feed lines. A complementary slot matching the radiating patch is introduced in the ground plane of the truncated semi-elliptical antenna element to obtain SWB. The designed MIMO/diversity antenna displays a bandwidth ratio of 31:1 and impedance bandwidth (|S11| ≤ − 10 dB) of 1.3–40 GHz. In addition, a complementary split-ring resonator (CSRR) is implanted in the resonating patch to eliminate WLAN (5.5 GHz) and X-band (8.5 GHz) signals from SWB. Further, an L-shaped slit is used to remove Wi-MAX (3.5 GHz) band interferences. The MIMO antenna prototype is fabricated, and a good agreement is achieved between the simulated and experimental outcomes.

A planar, microstrip line-fed, quad-port, multiple-input-multiple-output (MIMO) antenna with dual-band rejection features is proposed for ultra-wideband (UWB) applications. The proposed MIMO antenna design consists of four identical octagonal-shaped radiating elements, which are placed orthogonally to each other. The dual-band rejection property (3.5 GHz and 5.5 GHz corresponding to Wi-MAX and WLAN bands) was obtained by introducing a hexagonal-shaped complementary split-ring resonator (HCSRR) in the radiators of the designed antenna. The MIMO antenna was etched on low-cost FR-4 dielectric substrate of size 58 × 58 × 0.8 mm3. Isolation higher than 18 dB and envelope correlation coefficient (ECC) lesser than 0.07 was observed for the MIMO/diversity antenna in the operating range of 3–16 GHz. The presented four-port UWB MIMO antenna configuration was fabricated, and the experimental results validate the simulation outcomes.

This article presents a compact, planar, quad-port ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna with wide axial ratio bandwidth (ARBW). The proposed MIMO design consists of four identical square-shaped antenna elements, where each element is made up of a circular slotted ground plane and feed by a 50 Ω microstrip line. The circular polarization is achieved using a protruding hexagonal stub from the ground plane. The four elements of the MIMO antenna are placed orthogonally to each other to obtain high inter-element isolation. FR-4 dielectric substrate of size 45 × 45 × 1.6 mm3 is used for the antenna prototype, and a good agreement is noticed among the simulated and experimental results. The proposed MIMO antenna shows 3-dB ARBW of 52% (3.8–6.5 GHz) and impedance bandwidth (S11 ≤ −10 dB) of 144% (2.2–13.5 GHz).

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A novel design of a dual‐band dual‐sense circularly polarized square slot antenna with two rectangular shaped parasitic patches etched on a single substrate for 1.74/2.82 GHz applications is presented. A coplanar waveguide (CPW) fed line with two horizontal branches of different lengths is used, which produce two different frequencies bands. However, good circular polarization (CP) performance is achieved by adjusting the size of the parasitic patches. The two branches of feed line can excite dual‐band dual‐sense circular polarized wave. The antenna generates right hand circular polarization (RHCP) and left hand circular polarization (LHCP) radiation at 1.74 and 2.82 GHz, respectively. Lower band is obtained due to 90° phase difference between currents in the two orthogonal branches of the feed line. The lower band of CP is controlled by the size of parasitic patch/element (PE2) and the upper band of CP is controlled by length of right‐sided horizontal branch of feed line. The key parameters of the design are investigated to show how to obtain dual CP with impedance matching.