Defense Intelligence Reference Document High-Frequency Gravitational Wave Communications

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(2.8x10· 13)/(4xl0· 3) = 7x10- 11 wm- 2 . Thus A= 2x10· 33 . It is an extremely small
HFGW amplitude, but possibly a detectable signal.
2.1.2 Alternative Approaches
There are several alternative approaches to the laboratory generation of HFGWs
developed over the past 45 years as discussed in the preceding Section 2.1.1. They can
be categorized as EM-cavity generated, nuclear-energy generated, superconductor-
generated, laser-impact generated and energized microscopic & submicroscopic-particle
generated HFGWs. Of these categories the last category appears to be the most
promising for early deployment in HFGW communications systems. Furthermore, one
embodiment of that category: the Magnetron-energized FBARs generator, utilizing off-
the-shelf equipment, would seem the most useful for proof-of-concept tests. For a
practical, operational communications system HFGW generator (transmitter) the strong
dependence of HFGW generator's power on the number of radiating elements, N,
recommends a system utilizing molecular elements as suggested by Braginsky and
Rudenko (1978) or using Infrared (IR)-energized pentane molecules in a stack of
circular waveguides as proposed by Woods and Baker (2009). The Magnetron-energized
FBARs and the IR-energized pentane will be considered in the next-following sections.
2.1.3 Piezoelectric Approach
Let us consider the l.8x 10 8 cell-phone film bulk acoustic resonators or FBARs, 10,000
Microwave-Magnetron, proof-of-concept laboratory HFGW generator. Assuming a 10 μm
distance or margin between the 100 μm square conventional FBARs, the overall length
of the laboratory generator will be 110 x (lo- 6 m) x (1.8x10 8 elements)= 19.8 km. It
will have a total HFGW power of 0.066 Wand for a distance out from the last in-line, in-
phase FBAR element of one HFGW wavelength (6.1 cm) it will have a flux of 3.53 wm- 2,
yielding a HFGW amplitude there of A= 4.9x 10-28 m/m. By the way, the inline set of
FBAR elements also produces a more needlelike radiation pattern of HFGWs so that the
flux and resulting A may even be larger. Although the frequencies may be different
analyses (2003), one can extrapolate approximately from the results of Dehnen and
Romero-Borja's analyses in which the angle of the needle-like radiation pattern is
inversely proportional to the square root of the product of the distance between the
radiators (the width between FBAR bands or tracks) and N. The distance for the system
discussed here is 6.1 cm and for Dehnen's system 0.00001 m, for a factor of 6,100 and
N differs by (1.8x 108)/(Sx107 ) = 3.6 for a product of 2.2x 104 and the inverse of the
square root is 6.7x10-3 . Using the result from Dehnen's paper (Equation (4.51), page
12) of a needle half angle of 1.7 degrees we would extrapolate to 0.0115 degrees or
very approximately 2x 10-4 radians. Since there is no longer the constraint to the use of
rudimentary off-the-shelf components as there was for the proof-of-concept apparatus,
the specially designed submicroscopic elements can be manipulated. First, they will be
staggered into two bands or tracks of 100 rows each or 110 x 100 μm = 1.1 cm wide
bands of FBARs a wavelength or 6.1 cm apart. The rows will be staggered by displacing
adjacent rows in the bands by 1.1 μm. Thus the overall length will be reduced to 198
m. Second, the 100 μm length of each FBAR element can be sliced, along the direction
of travel of the HFGW build up, into one-hundred 1 μm wide slices (exhibiting 0.1 μm
margins). The staggered row displacements are now reduced to 11 nm. The overall
length will be reduced to about 198 cm. Concentrating the 10 MW power to each of
these 1.1 cm wide bands may prove to be difficult. Thus, as an example, the
continuous-wave Magnetrons will be replaced by a pulsed microwave source having
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