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Research Projects >> Other >> Current Research Project >>
Analysis, Design, and Fabrication of VHF and UHF Circulators
The concept of the Broadband Antenna Comb Circulator CLIC/CLAC (BA-C4) was
conceived from the observation that standard frequency-hopping, frequency-scanning
wideband transmitters and receivers are inherently expensive and not necessarily
functionally robust. From the receiver point of view, hopping filters are required to track
the signal and to prevent unwanted jamming interference from saturating the receiver. In
addition to the expense of designing and fabricating these filters, there are additional
costs in system complexity and integration associated with synchronizing the receiver
with the hopped signal. For near-range communications, diode limiters present in the
front-end of the receiver often introduce undesirable mixing harmonics in the selected
channel. Technological issues aside, a communications vehicle, such as the USMC Vehicular Radio Room, carrying such wideband transmitters and receivers, oftentimes
has multiple transmit and receive antennas mounted on it that provide an unwanted visual
signature.
The research thrust of this effort is to develop techniques and topologies for
wideband, high isolation circulator operation in the UHF and VHF bands. The primary
technique to be considered is the lumped element circulator, as described in the previous
paragraph, as one of many components in a filter or matching network circuit consisting
of additional inductors and capacitors. That is, the design technique will consider any
number of inductors, capacitors and lumped element circulators to form a filter-circulator
network. By having more than one degree of freedom, as in the standard lumped-element
circulator design, we have in the proposed method multiple degrees of freedom to pursue
multiple design objectives, i.e. bandwidth, passband shaping, return loss, insertion loss
and isolation.
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