Electromagnetics and Antennas

GPS and Cellular Antennas

We provide several GPS antennas with improved performances. The improvements are achieved in terms of higher gain, superior VSWR, wider coverage, reduced multipath, compact size, and smaller weight. A novel choke-ring with extremely small footprint is offered.

The antennas are provided as L1 only elements, L1 and L2 antennas, and L1, L2, L5 antennas. Antennas suitable for M-code and Galileo are available. Multiband antennas integrated with cellular bands are developed. Several CRPA antennas are also available.

Compact Dual-Band GPS Antenna

Covering L1 and L2 band

CRS’s compact dual-band GPS antenna is capable of operating at two GPS bands (L1: 1,575.42 MHz and L2: 1,227.60 MHz) with improved performances in terms of bandwidth, axial ratio, cross-pol rejection, and multipath rejection. It occupies minimal footprint (40mm x 40mm x 2.54mm). This antenna mounts flush on any flat surface. Magnetic mount and screw mount housings are both available. CRS’s compact dual-band antenna is suitable for a wide variety of airborne and vehicle tracking applications. It performs well as an external antenna for most of the common hand-held receivers. High-grade polymer resin is used for environmental resistance. It is also suitable for test applications with GPS receivers. This model is available in active with LNA or passive. Passive element can be used in GPS re-radiation application.

Tri-Band GPS Antenna

Covering L1, L2 and L5 band

CRS’s tri-band GPS antenna is the world first tri-band GPS antenna to cover three GPS bands (L1, L2 and L5). It is compact in size and has excellent multipath rejection capabilities. This antenna eliminates both co- and cross-polarization signals coming below the horizon. Superior cross-polarization rejection (-20dB) is achieved in upper hemisphere. The antenna is equipped with a new type of vertical choke ring developed by CRS (U.S. Patent 6,940,457 Sept. 6, 2005). The ring has identical performances to conventional choke rings, but at a greatly reduced size (25 percent smaller). Unlike conventional choke rings, it is designed to be effective for all operating frequencies. Typically, the multipath signal is in both polarizations. For a good multipath resiliency, the antenna must have minimal reception from the back size of the antenna for both polarizations. CRS's tri-band antenna takes the best countermeasure for this requirement.

Controlled Radiation Pattern Antenna (CRPA)

CRS has developed Controlled Radiation Pattern Arrays for GPS applications with anti--jamming capability to be installed on vehicles or aircrafts. The key factor in the array's performance is the number of antenna elements. CRS CRPAs are 7-element active phased arrays capable of nulling 6 jammers. CRS's CPRA uses a full polarization scheme (RHCP/LHCP, vertical-horizontal, or a combination of both), which significantly increases its nulling effectiveness. It prepares for all types of jammers by providing all types of polarizations for each elements, i.e., linear (V/H), circular (RHCP/LHCP), and elliptical. Spatial correlation is a negative factor in CRPA; the array elements in a conventional array must be placed far enough (at least half a wavelength) apart. A CRS CRPA utilizes novel EBG (Electromagnetic Band Gap) substrates to mitigate the mutual coupling effects between the array elements. This allows a 7-element CRPA to have less than 200mm diameter (conventional CRPA occupies 360mm diameter). The smaller CRPA can replace current FRPAs in many DoD applications, which currently cannot provide A/J capabilities. This antenna is also well-suited for commercial applications where digital beamforming is needed.