Mubarak Sani Ellis

A Novel Simple and Compact Microstrip-Fed Circularly Polarized Wide Slot Antenna With Wide Axial Ratio Bandwidth for C-Band Applications

This communication presents a design of a new compact circularly polarized (CP) slot antenna fed by a microstrip feedline. The 3-dB axial ratio band can be achieved by simply protruding a horizontal stub from the ground plane toward the center of the wide slot (WS) and then feeding the WS with a microstrip feedline positioned to the side of the WS, underneath the protruded stub. The feedline and metallic stub are perpendicular to each other, and they resemble a T shape when viewed from the top. The proposed antenna is fabricated with an area of 25 × 25 mm2. Measurement results show that the antenna attains an S11 ≤ -10 dB impedance matching bandwidth of 90.2%, from 3.5 to 9.25 GHz, and a broadband 3 dB-AR bandwidth of 40%, ranging from 4.6 to 6.9 GHz. A peak gain of 0.8-4.5 dBi is achieved within the AR band. The proposed antenna is suitable for circular polarization applications in C band.

A Printed Vivaldi Antenna with Improved Radiation Patterns by Using Two Pairs of Eye-Shaped Slots for UWB Applications

In this paper, a printed Vivaldi antenna with two pairs of eye-shaped slots is proposed for UWB applications. By using two pairs of eye-shaped slots, the side lobe levels of the radiation pattern are reduced, and the antenna gain is improved at low frequencies. To illustrate the efiectiveness of the proposed design, a prototype of the proposed antenna is fabricated and measured. Experimental results show that the proposed antenna presents a measured impedance bandwidth, deflned by jS11j < i10dB, from 3 to 12.8GHz with a compact size (36mm£36mm). Good unidirectional radiation characteristics with a front-to-back ratio better than 10dB are also achieved. The measured gain is better than 3.7dBi in the operating frequency band. In addition, the measured group delay of the proposed antenna is around 1.2ns with a variation less than §0:5ns.

A wideband single fed circularly polarized slot antenna for multi-band applications

In this paper, a single fed wideband circularly polarized slot antenna is proposed for multiband applications. The antenna consists of a rotated hexagonal slot with a parasitic patch placed in the slot which also has a thin slot in its center. The antenna has a feed-line offset which in addition to the parasitic stubs produce the two near degenerate orthogonal modes required for circular polarization. Simulation results have shown that the proposed antenna can achieve an operational bandwidth of 1.6-3.08 GHz for reflection coefficients below -10 dB representing a bandwidth of 60.4 % and an axial ratio below 3 dB between 2.04 GHz and 2.68 GHz. This represents an axial ratio bandwidth of 26.1 % with respect to the center frequency which was chosen as 2.45 GHz. The proposed antenna has a small size of 58 mm × 58 mm, a wide operational bandwidth and a wide 3 dB axial ratio bandwidth. This antenna can be used for wireless applications like RFID/UMTS/WLAN/WiMAX.

Dual-Band Dual-Sense Unidirectional Circularly Polarized Antenna with CPW-Fed for Wireless Applications

A novel dual-band unidirectional circularly polarized (CP) antenna fed by coplanar waveguide (CPW) for wireless applications is proposed. The antenna configuration consists of a ring- shaped ground, an F-shaped central strip and a spherical cap reflector. The longer and shorter branches of the F-shaped central strip help to produce radiations at lower and higher frequencies. The CP characteristics are achieved by adding two solid arcs and a grounded tuning stub. Both simulated and measured results are given and analyzed. Measurement results show a 10 dB return loss with a bandwidth of 56% (2.15 GHz-3.83 GHz) at 2.45 GHz (ISM), and a bandwidth of 42.6% (4.67 GHz- 7.2 GHz) at 5.8 GHz (HiperLAN), a 3 dB axial ratio bandwidth of 15.1% (2.25 GHz-2.62 GHz), 4.1% (5.67 GHz-5.91 GHz). The maximum gains within the two CP bands are 8.7 dBic and 10.2 dBic, respectively.

A Planar Monopole UWB Antenna with Improved Lower End Bandwidth Using an L-shaped Stub Extended on the Ground Plane

In this work, a planar monopole ultra-wideband (UWB) antenna with an L-shaped stub on the ground plane is proposed. The novel extended L-stub in conjunction with the UWB radiator achieves an ultra wideband impedance matching with a compact size. The proposed antenna is fabricated and measured showing an ultra wide operating frequency range from 2.3 to over 14GHz (VSWR < 2) with a unidirectional gain from 3{6.5dBi and e-ciency from 70{85% within the UWB band from 3.1{10.6GHz. The proposed antenna provides a new way to improve ultra wideband impedance matching other than the frequently used tapered microstrip feed line. It also provides a way to improve the lower frequency bandwidth of the antenna without increasing the antennas physical size, which is the most common method to use.

Miniature staircase profile printed monopole antenna for ultrawideband applications

A miniature planar monopole ultrawideband (UWB) antenna with a wide bandwidth is described. The radiator and ground plane are etched on 11mm×15 mm FR4 printed circuit board. Here, a staircase profile is made at the bottom and top parts of the radiator and ground plane respectively, to improve the impedance matching of the antenna. The proposed antenna has a useable fractional bandwidth of over 120% (7.5-30GHz for VSWR <; 2.5). The measured results show good far field radiation properties of the antenna.