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1. INTRODUCTION
The patent pending CMM200 Massive MIMO Modular Passive Panel is the preferred testbed for
Massive MIMO research, allowing the radio researcher ease and flexibility in assembling an array
of variable size and shape which always has constant array spacing for minimization of grating
lobes.
The modules attach to each other and to ground plane extensions with a proprietary fastening
design that enables quick assembly without threaded fasteners. When attached, a module-module
or module-extension connection has excellent ground plane continuity due to a conductive
elastomeric gasket around the periphery that ensures optimal field pattern from each element.
Each module has 16 patch antenna elements, each having a dual polarization with very high cross
polarization isolation and low mutual coupling between adjacent elements.
Massive MIMO reciprocity calibration is accomplished easily with the modules, because each
module has a network of couplers that meanders through the antenna PCB, coupling energy off of
each of the 2x16 radiating elements, and connecting to a common RF calibration (CAL) port. There
is also an additional port in this calibration network for daisy chaining the calibration line to other
modules (CAL_DAISY) which can permit a single connection to the reference radio used for
calibration.
The radiating elements are high-efficiency patch antennas which are soldered to the antenna PCB
for the highest reliability and performance. These exhibit good return loss and field pattern over
a broad bandwidth, enabling freedom of choice in the research frequency used.
The modules have an integrated radome made of high-impact UV stabilized plastic. The radome
is sealed to the housing with an O-ring which supports IP55 immersion rating for outdoor
operation.
Each module has on the back side a set of 34 SMA connectors for the 32 antenna ports and two
reciprocity calibration ports. The modules can be delivered pre-assembled with cables for
increased ease of use.
DSP-17-08-005/A/JD
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