MWA Active Crossed-Dipole Antenna (used in the Murchison Widefield Array)
If you are interested in ordering the MWA crossed-dipole antenna described below, click here.
The MWA active crossed-dipole antenna is a receive-only antenna with a design frequency range of 80 to 300 MHz. It complements the LWA active crossed-dipole antenna described here. Some of the original design documents for the MWA antenna system are available here.
The MWA antenna is a vertically oriented bow-tie design with elements that consist of triangular wings or blades as shown immediately below. The antenna central hub contains a dual low noise amplifier (LNA) assembly. Each LNA is powered through its coaxial cable by a bias-tee arrangement.
In the Murchison Widefield Array, "Tiles" consisting of sixteen crossed-dipole antennas are installed on a ground screen and connected to a beam forming assembly (shown in foreground below). With the beamformer, the antennas may be steered up to 30 degrees from vertical. We have a limited supply of the beamformer hardware but cannot supply and do not support the software for controlling it.
Transmission Line, Power and Protection Considerations
The dual low noise amplifier assembly in each crossed-dipole antenna is powered through individual bias-tees located at or near the receiver equipment. An MWA Power Controller, MWAPC, specifically designed for use with the MWA antenna that we sell, is under development. The MWAPC is a power coupler for one crossed-dipole assembly and is used in single installations (not tiles). When available, the MWAPC will be listed on the MWA ordering page. The MWAPC will be available with or without a quadrature coupler for discrimination of polarization (see Applications for Circular Polarization below).
A crossed-dipole antenna, such as the MWA antenna, can be setup to discriminate right-hand circular or left-hand circular polarization by combining the output of each dipole in a 90° hybrid coupler as shown below. For additional information, see Introduction to Radio Wave Polarization and Antenna Application for the Quadrature Coupler.
Our primary application for the active crossed-dipole antenna is reception of solar radio bursts, in which case we use the antenna with the CALLISTO instrument described here. When used with the CALLISTO instrument, the usable frequency range is 80 to 300 MHz.
If you are interested in ordering the MWA crossed-dipole antenna and associated active balun described above, click here.