Rao Shahid Aziz

Dual Polarized Dual Antennas for 1.7–2.1 GHz LTE Base Stations

A novel antenna with both horizontal and vertical polarizations is proposed for 1.7-2.1 GHz LTE band small cell base stations. Horizontal polarization is achieved by using the Vivaldi antennas at the main PCB board in azimuth plane, whereas the vertical polarization is obtained using the rectangular monopole with curved corners in proximity of the horizontal elements. A prototype antenna associated with 8-elements (four horizontal and four vertical) is fabricated on the FR4 substrate with the thickness of 0.2 cm and 0.12 cm for Vivaldi and monopole antennas, respectively. Experimental results have validated the design procedure of the antenna with a volume of 14 × 14 × 4.5 cm3 and indicated the realization of the requirements for the small cell base station applications.

Multiband Full-Metal-Rimmed Antenna Design for Smartphones

In this letter, a multiband full-metal-rimmed antenna covering 10 frequency bands for personal wireless communication terminals is presented. The design antenna is based on simple and effective techniques that are used for metal-rimmed smartphone applications. The proposed antenna with full metal rim is designed on RO4350B substrate within the volume of 130 × 70 × 5 mm3. We employed RO4350B substrate with inserted vias as metal rim with height of 5 mm, which surrounds the inner circuit board. The circuit board substrate has a ground plane, which is connected to the metal rim via extended substrate patch. This connection divides the rim into two metal rim strips. The combination of these two strips allows the design to operate on 10 bands. Performing perturbation on the ground plane further adds more operating bands and makes the design an excellent candidate for multiband operation. The designed antenna can be used to serve on GSM850/900, GPS, DCS, PCS, UMTS, WiBro at 2.35 GHz, Bluetooth, ISM, SDM-B at 2.65 GHz, WiMAX at 3.5 GHz, and C-band at 4 GHz wireless communication bands. A prototype antenna was fabricated and tested for input reflection coefficient, radiation performances, antenna gain, and efficiency. The measured and simulated results have been presented and discussed.

A Design of Multiband, Dual-Polarization, Beam-Switchable Dual-Antenna for Indoor Base Stations

A novel multiband, dual-polarization, beam-switched dual-antenna design, covering some LTE and WLAN bands, has been proposed for indoor base stations. The proposed design consists mainly of dual modifled monopole antennas. The horizontal antenna consists of four printed monopole elements, and the control circuit using p-i-n diodes has been implemented for feeding to each monopole element. The vertical monopole antenna beam patterns are controlled by reconflgurable frequency selective re∞ectors (RFSR) technique. The p-i-n diodes have been utilized for switching mechanism to feed the four RFSR. The measured and simulated results indicate that the antenna system possesses multiband and dual polarization. It has been observed from the simulated and measured re∞ection coe-cients jS11j that the presented dual antenna system supports both LTE (1.7{2.1GHz) and WLAN (2.5GHz and 5.8GHz) band frequencies. Moreover, the radiation characteristics show dual-polarization behaviors of the presented antenna system and beam switching states suitable for small cell indoor-base stations.

Design of Offset Dual-Reflector Antennas for Improving Isolation Level between Transmitter and Receiver Antennas

This paper presents the improved isolation property of the signals among transmitter and receiver antennas. The separation wall is laid at the center of the antennas to improve the isolation level between them. The introduced separation wall has serrated edges mounted on three sides, i.e., top, left and right sides. These mounted serrated edges are implemented to reduce the diffraction which may occur due to the linear edge of the wall. The Fresnel diffraction problem has been solved using analytical method in order to get the optimized structure of the serration. The Fresnel diffraction patterns due to different sizes of the serration are obtained, and their relative powers are compared to each other. The implemented antenna system with the serration wall is composed of corrugated feed horn, orthogonal mode transducer, and offset dual-reflector parabolic antennas. The effect of serration is well demonstrated by the measurement of isolation level of the antenna system. The measured results show that the serrated edges enhanced the isolation property among transmitter and receiver antennas.

Multi-band, dual polarization, dual antennas for beam reconfigurable antenna system for small cell base Station (Invited paper)

Multiband, dual polarization dual antennas for beam reconfigurable antenna system suitable for small cell indoor wireless base stations is proposed. The whole design consists of horizontal and vertical antennas on a PCB board. Both the antennas are printed monopole type. The antenna supports LTE (1.7-2.1 GHz) and WLAN (2.5 GHz and 5.75 GHz) band frequencies. The simulated reflection coefficients |S11| of the proposed antenna shows that at operating frequencies undergo sufficient bandwidth lower than -7dB. Additionally, radiation characteristic of the presented antenna shows dual polarization behavior and switching states of the beam.

Characterization of Rayleigh fading channel at 28 GHz using narrow and wide beamwidth antennas in reverberation chamber (Invited paper)

In this paper, channel characterization of Rayleigh fading channel at 28 GHz band is investigated. FMCW (Frequency-modulated continuous wave) radar is used as a channel sounder. The measurement is carried out inside the reverberation chamber with two different received antennas; one has 72.29° and the other has 2.40° of 3 dB beamwidth on azimuth plane. Different cases has examined with different arrangements of microwave absorbers. The obtained scattered plots and envelope distributions of Rayleigh fading channel has shown and discussed.

Rayleigh Fading Channel Characterization Using K-Band FMCW Radar in Reverberation Chamber

This paper investigates the channel characterization of Rayleigh fading channel using K- band frequency-modulated continuous wave (FMCW) radar system. An IF (intermediate frequency) signal of K-band FMCW radar can be treated as time and frequency domain signals due to a unique property of linear frequency modulation (LFM). First, channel sounder FMCW radar stability has been confirmed by measuring power flatness of transmitted radio frequency signal and estimated range in anechoic chamber before conducting the experiment for channel characterization of Rayleigh fading channel. Next, the measurement setup has been conducted in reverberation chamber which emulates multipath fading phenomena. In reverberation chamber, four different cases have been examined by changing the boundary conditions inside it with and without flat microwave absorbers. This investigation leads to obtained scattered plots, normalized propagation delay profiles (PDPs), mean excess delay, root-mean-square (RMS) delay spread and envelope distribution of Rayleigh fading channel at about 24.591 GHz.