Two new compact lens antenna configurations are presented and compared for data link communications with LEO satellites at 26 GHz These lenses match a secant type radiation pattern template in the elevation plane while having a mechanically scanned sector beam in azimuth to enhance gain as much as possible No rotary joints or multiple feeds are required and emphasis is put also on the compactness of the proposed solutions (< 6lambda0) Two alternative lens configurations are evaluated numerically and experimentally: one is based on modified axial-symmetric dome lens geometry, and the other one consists of a full 3-D double-shell lens antenna In contrast to current nearly omnidirectional antennas, the directivity of our lens prototypes is above 154 dBi Up to 42 dB loss obtained in the prototypes can be significantly reduced by using lower loss dielectrics and matching layers, without affecting the conclusions The numerical and experimental results are in good agreement with the radiation specifications given the compact size of the antennas

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Compact Ka-Band Lens Antennas for LEO Satellites

As the users call for the improvement of the datarate in GPRS system, so far an adaptive antenna implemented at base station is envisaged to be the solution. However, this concept introduces the problems of high expense and complexity. Alternatively, a switched beam antenna avoiding those impairments is worthwhile considering. Therefore, this paper investigates into the use of switched beam antenna compared with adaptive antenna in GPRS system. To achieve a fraction of expense, the implementation is considered at the mobile station instead. The simulation results reveal that employing the switched beam system provides higher performance in term of carrier-to-interference ratio and throughput, compared with adaptive antenna. The obtained results also confirm the advantages of switched beam antenna even though the system is situated in non-line-of-sight environment.

http://ieeexplore.ieee.org/iel5/4768556/4773649/04773730.pdf

Performance enhancement of GPRS transmission using switched beam antennas at Mobile Station

In this paper we present an optimum design procedure for pencil beam and spot beam arrays The procedure involves determination of optimum element size and number of elements that fulfill a desired gain of a scanned beam An illustrative example is presented to demonstrate the procedure It is found that such an optimum design could reduce 20% element counts while satisfying the gain requirement Three different types of radiating elements that are commonly used in phased arrays are examined from bandwidth and maximum scan angle point of views

Optimum design consideration for multiple spot beam array antennas

In last few years, a smart antenna has been envisaged to enhance the GPRS system implementing at Base Station. This results in the problem of complexity and expense. Alternatively, this paper considers employing switched beam antenna at Mobile Station, such as Laptop, instead. The simulation results reveal that utilizing switched beam antenna provides higher performance in term of C/I and throughput compared with using existing antenna. As being spaced by half-wavelength of the operational frequency, the array size is too large to build in Laptop. On the other hand, the reduction of array spacing affects the system throughput because of mutual coupling effect. Also, the decoupling techniques proposed in literatures are not practical for implementing in Mobile Station. Therefore, this paper also presents the trade off between throughput and array size. From the obtained results, we can reduce the array spacing according to the desired throughput. This is considerably useful for the GPRS designer.

Investigation into GPRS Transmission Employing Switched Beam Antenna at Mobile Station

Paratek Microwave, Inc. developed a multibeam phased array antenna system at 1.8 GHz, suitable for application as a smart GSM base station antenna. The antenna is also capable of handling GPRS and EDGE extensions to the basic GSM system. The antenna array elements are phased using phase shifters based on Parasca/spl trade/ voltage tunable materials. An antenna system overview and a description of the basic operation will be given, followed by system simulation and pattern measurement results.

Smart multibeam phased array antenna for GSM, GPRS and EDGE

The antenna presented uses vertical linear polarization and scans from -45/spl deg/ to +45/spl deg/ in the azimuth plane and has a fixed cosecant squared beam in the elevation plane This paper presents the performance and measurement results for a 1-D scanning phased array antenna with a 16/spl times/16 element configuration Gain is measured to be 225 dBi at 0/spl deg/ scan The measured radiation patterns, gains and active return loss for scans from -45/spl deg/ to +45/spl deg/ in 5/spl deg/ steps demonstrate consistent patterns with no grating lobes and blindness This performance is attributed to minimum mutual coupling effects of this microstrip patch array

E.P. Ekelman

Papers

Smart multibeam phased array antenna for GSM, GPRS and EDGE

Azimuth scanning, Ka-band phased array antenna