Wave action device for radio frequencies

A wave action device for beams of radio frequency waves operates as an electromagnetic lens at an electromagnetic wave relay station to redirect the electromagnetic beam in selective high concentration of the beam to one or more specific points. The device is positioned in the region of an electromagnetic wave link and intercepts the electromagnetic beam, barring that portion of the beam which forces the appearance of a null field at selected points of reception. The phase and the amplitude of the remaining portion of the intercepted electromagnetic beam are modified to redirect the remaining portion of the beam in a passive manner. The remaining portion of the beam is selectively concentrated and diverged with respect to the selected points of reception.

The present invention relates to a wave action device for radio 
frequencies. The device of the invention operates as an electromagnetic 
lens at relay stations of electromagnetic waves of any frequency in order 
to redirect the electromagnetic beam and provide an arbitrarily high 
concentration of such beam to one or more given points. 
SUMMARY OF THE INVENTION 
The principal object of the invention is to provide a wave action device 
for redirecting waves of any type and modifying the phase and amplitude of 
the waves. 
An object of the invention is to provide a wave action device which 
functions in accordance with Huyghen's theorem of wave propagation, as 
modified by Kirchhoff-Fresnel, to redirect and focus waves of any type. 
Another object of the invention is to provide a wave action device of 
practicable size, which is of simple structure and utilizes knife-edge 
diffraction to stabilize K factor variations in refractive conditions of 
the atmosphere. 
Still another object of the invention is to provide a wave action device 
which functions as a lens for waves of any type and stabilizes a beam of 
waves with respect to fluctuations in refractive index. 
Yet another object of the invention is to provide a wave action device 
which redirects waves of any type and provides them with real gain, as 
well as focussing them. 
Another object of the invention is to provide a wave action device of 
simple structure, which is inexpensive in manufacture and functions 
efficiently, effectively and reliably as a wave lens. 
Still another object of the invention is to provide a wave action device 
which functions efficiently, effectively and reliably as an 
electromagnetic lens at a location remote from the source of an 
electromagnetic beam. 
Yet another object of the invention is to provide a wave action device 
which redirects a microwave beam and provides it with super gain. 
Another object of the invention is to provide a wave action device which 
functions as an electromagnetic lens and may be made insensitive to K 
factor variations in refractive conditions of the atmosphere, so that it 
provides a total radiation pattern which always reaches the receiver and 
is always reached by the transmitter. 
In accordance with the invention, a wave action device for a wave beam 
emitted from a source, the wave action device operating as a lens at a 
relay station remote from the source of the beam to redirect the beam in 
selective high concentration of the beam to one or more specific points, 
the wave action device being positioned in the region of a wave link at 
the remote relay station, comprises a pair of spaced supports. An 
interceptor intercepts the beam to eliminate that portion of the beam 
which forces the appearance of a null field at selected points of 
reception. The interceptor comprises elongated spaced blades of 
predetermined dimensions positioned in a plane substantially transverse to 
the direction of propagation of the beam. The blades have spaces of 
predetermined dimensions between them. Each of the blades has a side 
knife-edge, spaced opposite ends and a longitudinal axis extending 
therebetween. Each of the blades has a width of a dimension determined by 
the operating characteristics of the device. The spaces have dimensions 
determined by the operating characteristics of the device. A modifier 
modifies the phase and the amplitude of the remaining portion of the 
intercepted beam to redirect the remaining portion of the beam in a 
passive manner. The modifier selectively concentrates and diverges the 
remaining portion of the beam with respect to the selected points of 
reception. The modifier comprises the spaces and the knife-edges of the 
blades for modifying the phase and the amplitude of the remaining portion 
of the beam. A mounting device mounts the blades at their ends on the 
supports in a manner whereby the blades lie substantially horizontally and 
are adjustably moveable relative to horizontal. 
The principle of the operation of the device of the invention is summed up 
as follows. In the space between two telecommunications relay stations 
there is electromagnetic energy in propagation. For a given instant of 
time, this wave energy is distributed in said space, with all possible 
phases. The corpuscular characteristics are not relevant. 
Accordingly, a device placed in said space which will either block or 
transform the phase of the electromagnetic energy distributed there, will 
necessarily cause a spatial rearrangement of all of the electromagnetic 
energy throughout the relevant space. If such blocking or phase 
transformation is carried out judiciously, two concomitant effects may 
result. One effect is the arbitrary redirection of the direction of 
propagation of the electromagnetic energy. The second effect is a 
measurable increase of the signal received by any of the relay stations at 
the terminals of the link served by the device. The signal may be even 
much stronger than that which an antenna could transmit to another on a 
direct line of sight. From these effects, it can be seen that the device 
has a convergent lens as its optical counterpart. 
The device may also be designed to operate as a divergent lens. One of its 
applications in this mode is to permit radio broadcasting in regions where 
a direct line of sight is not possible. In this case, redirection of the 
electromagnetic beam takes the form of a spreading or diffusion of said 
beam, and a measurable increase of the signal is obtained at points where 
there was no signal before or where its intensity was very weak. 
The device of the invention was conceived in accordance with the 
aforementioned principles of operation. The device of the invention 
basically comprises a plurality of metal screens, with mesh sized in 
accordance with the frequency and polarization of the electromagnetic 
energy in question, or metal blades. The metal blades are appropriately 
sized and supported at their ends on adequate pylons or brackets and are 
positioned so that there is a space between next-adjacent ones of said 
blades. The spaces between the blades are also appropriately sized and 
positioned. 
The metal blades or screens may also be replaced by blades of dielectric 
material having appropriate electric characteristics, size and 
positioning. The dielectric material may also occupy the spaces between 
the blades. 
The electromagnetic lens thus formed may be adapted to use by mounting the 
blades, screens or dielectric material so they may be displaced vertically 
and horizontally. This type of construction has the advantage of allowing 
sharper tuning of the lens. With such appropriate sizing and positioning, 
it is possible to obtain a suppression of most of the atmospheric effects, 
notably refraction, which in technical parlance is referred to as the K 
factor. The K factor defines the Earth radius equivalent and is K times 
the real radius of the Earth. The effects of interference are also 
considerably reduced, whether the interference be from reflections of the 
transmitted signal by the soil or in the atmosphere, or due to signals 
from other radio sources. 
In complete analogy to optical systems, it is also possible to form systems 
consisting of various lenses or several lenses with reflectors. The 
advantages of these systems are countless. The association of lenses 
allows original solutions to numberless problems in telecommunications, as 
hereinafter explained. 
As indicated by the foregoing, the device of the invention is passive. That 
is, it does not consume power, and requires no external source of power 
during operation. The device has two characteristic properties with regard 
to its action on a beam of electromagnetic waves of any frequency. First, 
the device is capable of directing an electromagnetic beam. Second, the 
device is capable of obtaining an arbitrarily high concentration of that 
beam to one or more given points. 
Thus, if a given point in space is not receiving the electromagnetic beam, 
one may, by using the device of the invention, force the magnetic beam to 
move through that point and, furthermore, force the beam to concentrate on 
that point. This results in a weak intensity electromagnetic signal at 
said point in space, having its intensity increased. The passive device of 
the invention therefore provides gain.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIGS. 1, 1a, 2 and 2a show an analogy between an embodiment of the device 
of the invention and a convergent lens. FIGS. 1 and 1a illustrate the 
action of a convergent lens L, or a segment S of the lens, on light rays. 
The image I to the object O is conjugated and F are the foci. FIG. 2 
illustrates the action of the passive device D of the invention on a beam 
of radio waves. The device D receives the radio beam from an antenna A, 
redirecting some of its rays to a receiving antenna A', on a direct line 
of sight with the transmitting antenna A. The beam is limited by rays 1 
and 4, while rays 2 and 3 correspond to the light rays of the diagram of 
FIG. 1. 
FIG. 2a illustrates the action of a segment Sd of the passive device on a 
beam of radio waves. In this case, the segment Sd of the device receives 
the divergent beam from the transmitting antenna A, redirecting the 
intercepted rays to concentrate them on the receiving antenna A', the 
direct line of sight between the antennae being blocked by a mountain. The 
segment Sd of the device acts on the intercepted rays in a manner 
analogous to that illustrated in FIG. 1a, for the segment of convergent 
lens S. 
FIGS. 3 and 3a show an analogy between another embodiment of the passive 
device and a divergent lens. In FIG. 3, showing a segment S1 of the 
divergent lens, the object O is real and the image I is virtual. In FIG. 
3a, the segment Sd1 of the passive device receives the divergent beam of 
electromagnetic waves transmitted by a transmitter T and redirects such 
beam to receivers R1, R2 and R3, which have their lines of sight to the 
transmitter blocked, by, for example, mountains. Transmission is 
undertaken as if the transmitter T were at I. It is obvious that such an 
arrangement has a great and important application in radio and TV 
broadcasting, since the passive device diverges the electromagnetic beam 
instead of concentrating it at a point. 
The passive device of the invention is fundamentally a pure wave device and 
functions with waves of any nature; mechanical such as, for example, 
sound, water, wind, or the like, electromagnetic, or other. 
The passive device of the invention may be basically built with metal 
elements or elements of dielectric material. The device may also be built 
with elements of a hybrid type made of metal and dielectric material. 
As shown in FIG. 4, the metal type passive device of the invention 
comprises a plurality of metal blades 11 of appropriate size and position. 
The blades 11 are mounted at their ends on supports 12, which may be of 
any suitable structural form. In the embodiment of FIG. 4, the supports 12 
take the shape of two vertical towers, standing a distance apart 
approximately equal to the length of the blades 11 and maintained erect by 
means of adequate guy wires 13. 
The metal blades 11 are mounted on, and extend between, the supports 12 in 
a manner whereby spaces 14 are formed between next-adjacent blades. As 
hereinbefore mentioned, both the width and length dimensions of each blade 
and the spaces 14 between them are provided specifically for each specific 
case. These dimensions define the activity of the device 10. 
In FIG. 4, the blades 11 are positioned parallel to each other. It should 
be understood, however, that parallel arrangement of the blades is not 
obligatory and the blades may occupy other relative positions, as shown in 
FIG. 5. The positions of the blades are specifically determined for the 
programmed operating characteristics of the wave action device of the 
invention. 
Due to its operating characteristics, the device of the invention requires 
accurate installation in order to provide the proper tuning of the 
transmitting and receiving stations. It is therefore essential that 
careful field measurements, including topographical data, among others, be 
taken, taking into consideration the relevant corrections such as optical, 
for instruments, atmospheric, etc. This enables the construction of the 
wave action device of the invention with the correct measurements and 
positioning and provides as perfect a tuning as possible. 
The wave device of the invention is built with its blades 11 rigidly 
affixed to the supports 12. Thus, if an error occurs in the positioning of 
the device after field assembly thereof, adjustment of the tuning requires 
specified adaptations to the stations at the ends of the link served by 
the device. On this account, this type of tuning adjustment is not 
discussed herein. In order to provide the wave action device of the 
invention with some versatility with regard to the required accuracy of 
its positioning, means may be provided to permit a tuning adjustment by 
moving the blades. One of the adjustment systems comprises the use of 
blades capable of rotating on their longitudinal axes, in order to offer a 
variable effective area to the receiving direction of the electromagnetic 
beams, more particularly, by varying the width of the spaces between the 
blades. In this embodiment, the blades may rotate together through the 
same angle or individually through different angles. 
Any suitable means may be utilized to mechanically affix and move the 
blades in relation to the supporting towers, including devices for manual 
or non-manual actuation. 
In the blade adjustment system shown in FIG. 6, a given group of blades 11 
is affixed at its ends to two rigid rods 16, only one of which rods is 
shown in FIG. 6. The rods 16 are displaceable along guide rails 17 affixed 
to each of the towers 12. The group of blades may thus be moved vertically 
via suitable means and/or devices such as, for example, cables and 
pulleys. Each mentioned group of blades 11 may include all the blades in 
the wave action device or only part of them. FIG. 6 illustrates, as an 
example, one of the numberless configurations of a blade adjustment 
system. 
Although it is not shown in the Figs., another blade adjustment system is 
obvious. Such a system includes both devices of the aforementioned two 
adjustment systems. Thus, in the third system, the blades 11 of one of the 
groups of blades may be displaced vertically and by rotation. 
FIG. 7 shows a fourth tuning or blade adjustment system comprising the 
assembly of a set of blades 11 between two opposite end rods 16 supported 
by towers or supports 12 via cables 18. Although complex in structure, 
this system provides great flexibility of positioning of the wave action 
device after it has been assembled in the field. The set of blades may be 
moved both vertically and horizontally and its inclination may be varied. 
A radical manner of retuning a considerably out-of-tune wave action device 
of the invention is by using a second wave action device to operate in 
conjunction with the first. In optics, the system corresponds to the use 
of various lenses in conjunction, in order to obtain specific purposes. 
Although the blades 11 have hereinbefore been described as metallic and 
integral, they may be formed of metal screens 11a of appropriate mesh and 
dimensions, as shown in FIG. 8. A blade 11a may be constructed from a 
metal screen in various ways. One of the possible constructions is the 
attachment of a screen 19 to a metal frame 20 provided with crossbars 21 
(FIG. 8). 
As hereinbefore noted in connection with the embodiment of the device 
constructed of metal blades, the spaces between the metal screens are 
sized for each specific case in which the device is provided for use. This 
sizing, of course, depends upon the distance between the antennae, the 
height of any obstruction interposed in the line of sight between the 
transmitter and receiver, and the wavelength of the electromagnetic beam. 
Several optimizations may be obtained by properly and suitably selecting 
the dimensions of the apertures and spaces, not keeping them constant, and 
also suitably positioning them. 
In one specific embodiment, the device was designed for a 39.5 km microwave 
link operating in the 7.5 GHz band. The link had an obstruction at 5.3 km 
from one of the ends. The relative positions of the antennae were such 
that the line of sight intersected the obstruction at 13.2 m below its 
top. A device was constructed comprising five metal screens horizontally 
extending between a pair of supports. In order to provide space for a 
potential obstruction, the lowest screen had a height of 2.67 m and had 
its lowermost edge located at a height of 14.71 m from the ground. The 
second screen had a height of 2.07 m and had its lowermost edge located at 
19.56 m from the ground. The third lowest screen had a height of 1.90 m 
and had its lowermost edge located 23.61 m from the ground. The fourth 
lowest screen had a height of 1.77 m and had its lowermost edge located 
27.34 m from the ground. The highest screen had a height of 1.66 m and had 
its lowermost edge located 30.83 m from the ground. The wavelength of the 
beam was 0.04 m. The device brought the signal at reception to its free 
space value of -38 dBm, that is, that value which it would attain if the 
transmission from one station to another were not impaired by an 
intervening obstruction. The transmitter power was +27 dBm and the total 
antenna gain was 89.4 dB. 
As hereinbefore mentioned, several optimum configurations may be obtained 
for a particular case and such configurations are easily arrived at by 
known mathematical calculations for each specific case. 
Both the metal plate blades 11 and the metal screen blades 11a may include 
structural reinforcements in them, as hereinafter described. These 
reinforcements prevent great deformation of the blades by the action of 
the winds. The metal type wave action device makes use of its blades 11 or 
11a to bar part of the electromagnetic beam, specifically that part which 
forces the appearance of a null field at the point of reception. The free 
space between the blades permits the convenient part of the beam to pass. 
Thus, all the dimensions and positions of all the components of the device 
of the invention are critical. 
As hereinbefore mentioned, the wave action device may have blades made of 
dielectric material. In FIGS. 9, 9a, 9b, 9c and 9d are shown different 
shapes for blades 11c of dielectric material. In this case, either the 
blades 11c occupy all the effective area of the device, thus eliminating 
the so-called "empty spaces", or said blades are spaced in the same manner 
as described for the metal blades, in which case blades 11d of dielectric 
material having a cross-section like that illustrated in FIG. 9d are used. 
Everything hereinbefore stated with regard to the wave action device of the 
invention having metal blades applies to the device having blades of 
dielectric material. An exception is that the device having blades of 
dielectric material operates to continuously modify the phase distribution 
in a plane, preferably, but not necessarily, transverse to, the 
propagation of the beam, whereas the device having metal blades modifies 
the phase distribution noncontinuously. This is due to the fact that the 
metal blade device, upon barring portions of the beam, introduces 
equivalent modifications of phases and amplitudes. 
It is apparent that devices with blades of dielectric material are much 
more efficient. In devices where the blades 11d (FIG. 9d) are mutually 
spaced, both the "empty spaces" and the blades themselves act to redirect 
the electromagnetic beam. In devices where the blades 11c (FIGS. 9, 9a, 9b 
and 9c) occupy all of the area of the device, the efficiency is even 
greater. The entire intercepted portion of the beam is redirected to the 
subsequent station. 
A dielectric or dielectric material is usually characterized by a parameter 
(E) called the dielectric parameter. In general, (E) is a complex number 
describing an ohmic or heat loss characteristic of the dielectric and a 
phase lag. As a rule, dielectrics can and should be selected with a 
negligible ohmic loss, which is characterized by (E)s have a small real 
value. 
Constancy of the value of the parameter (E) is a primary requirement in the 
manufacture of devices having blades of dielectric material. It is such 
constancy which expresses the degree of homogeneousness of the dielectric 
and make the operation of the system of the device successful or a 
failure. 
Another version of the wave action device of the invention utilizes blades 
made of artificial dielectric material which consists of a set of metal 
elements maintained in relative fixed positions by dielectric elements. 
The blades have an equivalent dielectric parameter (Eeq) which differs 
from the dielectric parameter (E) of the dielectric material used. Thus, 
the metal elements vary the dielectric parameter of a given dielectric 
material. 
Everything hereinbefore stated concerning devices with metal blades and 
with blades of dielectric material also holds for devices with hybrid 
blades of dielectric material and metal. The hybrid blade permits an even 
more varied geometry than either the metal or the dielectric material 
blade. It is possible to obtain elements corresponding to all optical 
counterparts. 
The wave action device of the invention has hereinbefore been approached, 
with respect to its method of operation, as being set up to operate 
continuously. Such devices may however be designed to operate 
intermittently, thereby assuring radio links in situations where such 
links are obstructed by changes in the normal atmospheric conditions of 
the region. A link served by low, and therefore cheaper, towers may be 
unobstructed for the normal conditions of the atmosphere of the region. 
However, it may happen, with a change of atmospheric conditions and, 
therefore, of the refraction index of the atmosphere, that the link will 
become obstructed, that is, that the radio waves which previously reached 
the receiver cease to do so, due to the redirection imposed by the changed 
atmospheric conditions. 
In the foregoing circumstances, a wave action device of the invention may 
be provided and installed in the region of the link, so that it operates 
only under normal atmospheric conditions. Accordingly, in normal 
circumstances, the "intermittent" device will operate little or not at 
all. With the change of atmospheric conditions, the radio waves which 
seldom or never reached the intermittent device, will start reaching said 
device and permit it to act to offset the losses incurred from the 
redirection of radio waves in consequence of the change in atmospheric 
conditions. In such application, the heights of the expensive towers of 
the terminal stations of a radio link may be substantially reduced if an 
auxiliary wave action device is provided at the link to operate 
intermittently. 
The wave action devices of the invention may be used in association with 
reflectors. The use of reflectors is well known in telecommunications. The 
reflecting parabola of the antennae used in microwaves is an example of 
such use. There are also large-dimensioned flat reflectors, some measuring 
as much as 10 m by 12 m, constructed at elevated locations in the general 
area of the link, whence they reflect the electromagnetic beam. FIG. 10 
illustrates the use of a reflector r operating as a mirror so as to 
reflect the waves transmitted from the transmitting station T to the 
receiving station R. The stations T and R are on a direct line of sight 
obstructed by a mountain M. One of the great advantages of the use of 
reflectors in conventional systems is the great distances they reach. 
FIG. 11 illustrates, by its optical counterpart, the effect of a wave 
action device operating as a convergent lens L on the electromagnetic beam 
to be picked by a reflector or mirror r. It is evident that if the 
convergent lens L device is removed, the reflector or mirror r will have 
to be much larger in order to catch the beam of waves. The economical 
advantages are great. The construction of a wave device is much simpler 
and cheaper than the construction and assembly of a large reflector. In 
addition, a small reflector is much cheaper in construction and 
installation. Being small-sized, the reflector offers a small area of 
resistance to the wind, requiring much more modest foundations and 
structures. 
Other configurations and applications of the wave action device of the 
invention are hereinafter described. 
A satisfactory and original configuration of the device with blades 11a 
formed by metal screens for certain circumstances consists of affixing the 
screen 19 between two cables 23 affixed to the supports or towers 12, as 
shown in FIG. 12. The method of affixing the screen 19 to the cables 23 is 
illustrated in FIG. 12a and comprises the use of two continuous clamps 24. 
Each of the clamps 24 lodges and holds one of the side edges of the screen 
19 between its continuous lugs 25. Each of the clamps 24 lodges one of the 
cables 23 in its tubular portion. Each clamp 24 has a longitudinal flange 
26 essentially diametrically opposite its two lugs 25. The flanges 26 
provide a "knife-edge" at the sides of the screen blade 11a. 
The wave action device of the invention having solid or screen-type metal 
blades takes the form, in given circumstances, of a metallized wall of 
brick, stone, or even a metallized wooden fence, properly dimensioned and 
positioned, and having edges properly trimmed. Such a wave action device 
is shown in FIG. 13. 
With regard to mechanical performance, the wave action devices hereinbefore 
described will endure a great load produced by the wind. In such 
circumstances, the metal blades should be fitted with structural 
reinforcing elements to prevent deformation due to great bending and 
twisting. FIG. 14 illustrates, by way of example, a metal blade 11 fitted 
with an angle plate 27 welded longitudinally to one of the faces of said 
blade. Guide rings 28 are welded to the angle plate 27, internally, at the 
vertex of said angle plate. A cable 29 passes through the guide rings 28. 
Metal cross bars 27a are also provided and welded to the blade 11 and the 
angle plate 27. The blade of FIG. 14 is mounted between the supports or 
towers and cable 29 is made taut and affixed to said towers. In such an 
arrangement, the cable 29 functions as a check to the bending moment to 
prevent the blade from bending. The cross bars 27a limit the deformation 
of the blade by torsion. 
The blades and supports may be ruggedly constructed, in various ways, to 
withstand the action of the wind. However, it is always advantageous to 
have a device which offers the least possible resistance to the wind. 
FIG. 15 illustrates a metal blade 30 made of four sheets or vanes angularly 
spaced 90.degree. from each other. The blade is assembled between the 
towers or supports by any suitable means which enables it to rotate about 
an axis defined by the intersection of the planes of the vanes. The number 
of sheets or vanes may be greater than 4 in number and said sheets may be 
constructed of metal screen. 
Rotation of the blade 30 does not significantly alter the electrodynamic 
performance of the wave action device, due to two features. The first 
feature is that the effective area, per blade, which prevents the passing 
of the electromagnetic waves does not vary much. When two coplanar vanes 
begin leaving the vertical position, two others begin to move into that 
position. The second feature is that there is normally a reasonable number 
of blades in a wave action device which will not rotate in synchronism, 
and an even smaller number of blades in synchronism. Thus, the fluctuation 
of the total effective area of the device tends to be minimal. 
As shown in FIG. 15, one of the vanes may support an end counterweight 31. 
The counterweight 31 guarantees the normal position of a pair of vanes 
when there is no wind. This system of rotating blades has the great 
advantage of permitting the use of lighter and flimsier supporting 
structures. 
The described devices require a strict location, permitting only a specific 
structural flexibility in the direction of propagation of the 
electromagnetic beam. The devices also have the capacity of deflecting the 
electronic beam sideways, so there is no need to locate a device on the 
line of sight of the terminal stations. 
As hereinbefore mentioned, the dimensions of the blades, their spacing and 
their positioning are critical. The technique for computing these 
parameters provides the resultant device with a performance which is 
practically independent of variations of the index of refraction of the 
atmosphere. 
The wave action device of the invention functions according to the 
principle of what is called in telecommunications parlance and in that of 
the theory of diffraction, a "knife-edge". An obstruction to the 
propagation of a beam of radio waves results in the introduction of a loss 
or an additional gain. The wave action device of the invention embodies 
the principle of the "knife-edge" curve. This principle was purely 
theoretical until the time of the present invention. The "knife-edge" 
curve does not have variations as sharp as those of the "round Earth" and 
"flat Earth" curves. The principle of the "knife-edge" curve is utilized 
to determined the ground clearance of the line of sight, as shown in FIGS. 
16a, 16b and 16c. The following abbreviations, having the following 
meanings, appear in FIGS. 16a, and 16b and 16c. 
T=transmitter 
R=receiver 
F=the ground clearance of the line of sight 
d.sub.1 and d.sub.2 =distances from transmitter and receiver to the 
"knife-edge" point 
h.sub.1 and h.sub.2 =heights of transmitter and receiver 
dB=decibel 
Fl=first Fresnel zone 
Gf="knife-edge" curve 
T.sub.e ="spherical Earth" curve 
T.sub.p ="plane Earth" or "flat Earth" curve 
n=(F/Fl).sup.2 
The ground clearance of the line of sight varies with atmospheric 
conditions, since such conditions refract the electromagnetic waves. This 
causes the waves to approach or move away from the surface of the ground. 
This is described by the so-called "K factor" which represents the 
phenomenon quantitatively. When the device of the invention is properly 
constructed, it simulates the "knife-edge" condition, making the link 
essentially indifferent to variation of the factor K. 
An important problem, as hereinbefore pointed out, which the device of the 
invention overcomes is the action of the wind. This may be translated into 
a several tons load, since the physical area of the device may be hundreds 
of square meters in magnitude in the worst cases. The mechanical 
configurations shown in FIGS. 6 to 15, although they are illustrative, are 
not optimal for wind loading. 
The embodiment of FIG. 12a is adequate within certain limits, for wind 
loading, since it utilizes a metal mesh having holes which permit an 
almost free flow of air. 
The embodiment of FIG. 14 is also suitable, if made of high tensile metal 
permitting flection and especially permitting torsion around its 
longitudinal axis. This permits an adaptation to the wind loading, due to 
the minimization of the wind resisting area by the torsion. In this case, 
the reinforcements 27a of the embodiment of FIG. 14 should not be 
utilized. 
The embodiment of FIG. 15 is also quite suitable to solve the wind loading 
problem. It can, however, be an expensive proposition. 
FIGS. 17a to 17e show another embodiment of the mechanical configuration of 
the blades. The embodiment of FIGS. 17a to 17e has the following 
advantages. It minimizes the wind action on the blades. It gives the 
blades very high resistance to both flection and torsion. It minimizes 
loads transmitted to the supporting towers or other structures of the 
device. It introduces a fail safe characteristic to the device. 
In the embodiment of FIGS. 17a to 17e, the blade 40 is formed by two 
similarly shaped blades 42 and 43 (FIG. 17a) in order to minimize wind 
loading. A saving of material is achieved by making the two blades 42 and 
43 of different widths. The blades 42 and 43 are joined by rivets 44 (FIG. 
17a). The basic blade of the wave action device is therefore hollow, as 
shown in FIGS. 17a and 17c. This maximizes its resistance both to 
flectional and torsional loads. 
The blades 40 are not rigidly affixed to the towers or other supporting 
structures. Instead, supporting structures 50 (FIG. 17c) are affixed to 
the towers via bolts, pressure washers and nuts. The supporting structures 
50 are so dimensioned that they fit snugly within the hollow blades 40 of 
the device (FIG. 17c). The supporting structures 50 are usually, but not 
necessarily, made of steel. The blades 40 may be made of aluminum. Since 
the contact of aluminum and steel is not recommended, Nylon washers 52 are 
mounted on the supporting structures, as shown in FIGS. 17d and 17e. The 
washers 52 may be of any suitable material other than Nylon. The washers 
52 are affixed to the supporting structure 50 by adhesive, rails, or 
screws 53 and nuts 54 and pressure washers 55, as shown in FIG. 17e. 
The Nylon washers 52 also decrease the friction between the blades 40 and 
blade-connecting members 51. 
The blade 40 of the embodiment of FIGS. 17a to 17e is essentially free from 
the towers, since it is able to slidably move over the Nylon washers 52. 
In this manner, the blade 40 adapts to stresses and strains. This 
minimizes all stresses and strains throughout the structure. 
If the wind loads are extreme, the blade 40 will snap off the supporting 
hand-like structures, but will be prevented from flying away by an 
internal cable 58 (FIG. 17b) acting as a failsafe device. The blade 40 
will thus be free to rotate, so that an exceptional wind load will never 
be transferred to the towers. 
The wave action device of the invention may be used to increase the gain of 
antennae of radio links. The antennae at the terminal stations in radio 
links may have their gains, or directivity of efficiency of radiation in a 
particular direction, substantially increased by simply installing the 
wave action device at a nearby distance, alongside the main direction of 
radiation. This distance is typically a few hundred meters long. Care must 
be taken that the wave action device is in a "distant field condition", 
which is a condition characterized by both the frequency of the radiation 
as well as the dimensions concerned. 
If the antennae are parabolic, such as those used in microwave 
transmission, the device is preferably constructed as several concentric 
rings. Each ring increases the power gain of the antenna by factor of 
four, at most, when the wave action device has screen type blades. The 
increase in power gain is even greater when the wave action device has 
blades of dielectric material. The concentric ring embodiment is 
illustrated in FIG. 18. 
For radio links subjected to strong attenuation of signals due to rain 
and/or fog, the concentric ring device, applied with one or more rings to 
either or both terminals of the radio link, very economically increases 
the signal intensity sufficiently to compensate for the rain and/or fog 
attenuation. In proper circumstances and care the concentric ring type 
device of the invention may also be used in the set antenna/passive 
reflector when the antenna and reflector are in a periscope type 
arrangement. In such an arrangement, the antenna is at the foot of a 
tower, the reflector is at the top of the tower and the device is 
inbetween the antenna and the reflector. 
The wave action device of the invention may also be used as a multifocal 
lens. The focussing property of the device depends upon the frequency of 
the signal being processed. In this manner, a single wave action device 
may be used to focus signals of different points in the same vertical 
plane, as illustrated in FIG. 19a. 
If no height clearance is available at the station tower, the wave action 
device of the invention may be built as a multi-foci lens, a bifocal being 
the simplest case. In this case, the wave action device is simply the 
consolidation of two or more wave action devices into a single structure, 
illustrated in FIG. 19b. 
The following example of the structure and operation of the wave action 
device of the invention utilizes electromagnetic waves for illustrative 
purposes only, due to the popular application of such waves in 
telecommunications. Accordingly, the basic theory of operation of the wave 
action device of the invention is confined to electromagnetic terms and 
circumstances. It is emphasized, however, that this is incidental. The 
device of the invention is a wave device. No basic electromagnetic 
phenomena is required to support its operation, except for the fact that a 
suitable wire mesh may bar a radio frequency or rf wave. Other, different, 
materials block other types of waves such as, for example, acoustical 
waves. Selective and appropriate blockage is all that is required. 
The basic theory of operation is just Huyghen's theorem of wave 
propagation, as modified by Kirchhoff-Fresnel, which applies to waves in 
general, its physical intrinsic nature not withstanding. A surface S is 
considered to be any imaginary surface immersed in the field of a wave in 
a manner whereby the field of the wave at each point of S has a specific 
magnitude F and phase .phi.. The field at a point P not belonging to the 
surface S, is defined as (FIG. 20) 
##EQU1## 
It is clear from Equation (1) that a suitable choice of S, and consequently 
of the values F(p) for a given original source of the beam, permits F(P) 
to assume a wide range of pre-assigned values. 
The wave action device of the invention is a materially feasible 
realization of the theorem of wave propagation, also taking into 
consideration other factors such as, for example, the K factor in the case 
of electromagnetic waves, occurring in nature. The device of the invention 
does not depend upon the specific nature of the wave. 
A typical telecommunication problem situation is the case of a link being 
greatly obstructed. The solution of this problem by the wave action device 
of the invention is described in the following specific example. The 
device of the invention in telecommunications may be treated as a limiting 
case of two back-to-back antennae. 
In the systems engineering of the basic wave action device, the ability to 
provide real gain and to redirect a microwave beam are the features of 
said basic wave action device which raise the most questions. These 
questions do not arise for reflectors, since mirrors are an everyday 
experience for everyone. The wave action device, on the other hand, is not 
commonplace at all, and there is no daily experience with it. 
The working principle of electromagnetic lenses, of which the wave action 
device of the invention is but one, albeit important, case, is as follows, 
using a system point of view. Basically, the wave action device may be 
thought of as a limiting case of two back-to-back antennae. The 
redirectioning of the beam from direction 1 to direction 2 is achieved by 
the device through controlled interference. This is illustrated in FIGS. 
21a and 21b. 
The back-to-back antenna system, as a whole, contributes a 2GdB gain to the 
link. The wave action device of the invention provides the same gain. The 
wave action device may thus be dimensioned in very much the same way as a 
back-to-back system. 
A worse condition is assumed in an example in which the wave action device 
of the invention is positioned at the mid-point of a 50 km link, with f=8 
GHz. TX power is 30 dBm. The receiver threshold is -75 dBm. The margin of 
fading should be at least 35 dB. The wave action device is at the top of a 
1000 m midlink obstruction. The specific wave action device required is 
determined as follows. 
If there were no obstruction, so that no wave action device would be 
required, six foot antennae could be used at the receivers. If 
miscellaneous losses of 6dB are assumed, the received signal would be at 
-38.1 dBm corresponding to a 36.9 dB margin of fading. This would satisfy 
the requirements. Since there is an obstruction, antennae with 10 foot 
diameters could be used, thereby accruing a 8.6 dB total advantage. This 
is a reasonable engineering move. In addition, it is possible to expect 
savings of at least 1.4 dB in waveguide losses by lowering the antennae, 
since the antennae do not have to be high up when the wave action device 
of the invention is used. This is a very conservative estimate. Such 
savings in waveguide loss could easily run as high as 7 dB. 
With these moves accomplished, what is needed is a wave action device 
having a 2 GdB gain, so that by functioning as a back-to-back antenna 
system it will guarantee the original -38.1 dBm signal. The power balance 
equation for this configuration is 
##EQU2## 
This results in 
EQU G.sub.D =61.25 dB (3) 
If actual parabolic antennae were used to implement the back-to-back 
configuration, they would require diameters larger than 60 feet. This is 
practically impossible. Wave action devices with this type of gain, 
however, are easily constructed. A great advantage of the wave action 
devices is that they bypass the mechanical impossibility posed by very 
large diameter parabolic antennae and are of practicable size. The wave 
action devices of the invention are thus also known as super gain 
antennae. 
The geometric area of the screen of the wave action device can be shown to 
be given by 
##EQU3## 
from which 
##EQU4## 
This is a perfectly viable device. It would consist of metal strips about 
22 m long, and with their mutual spaces and widths adding to about 23 m. 
The entire lens could be kept in place by three 39 m guyed towers, as 
illustrated in FIG. 22. 
The primary advantage of the aforedescribed procedure for dimensioning the 
wave action device is that it bears entirely on the well known and 
familiar back-to-back antenna system. A more direct method utilizes the 
expression. 
##EQU5## 
where the symbols are those of FIG. 23 and .alpha. is the attenuation, 
that is, the ratio of the desired received signal to the signal received 
under free space conditions, all other conditions remaining the same. 
Thus, in the example, the desired received signal is -38.1 dB whereas in 
free space conditions it would be -28.1 dB. Hence .alpha.=-10 dB or 
.alpha.=1/10. The expression for A.sub.geom will then be 
##EQU6## 
or, as before, 
EQU A.sub.geom .congruent.234 m.sup.2 (5) 
It is very revealing to extend the comparison between the back-to-back 
antenna systems and the wave action devices to economic areas. 
The wave action device of the invention performs the same function as a 
back-to-back antenna system. More specifically, it redirects the beam and 
furnishes gain to the signal. Hence, from a system point of view there is 
no basic difference between the device and the antenna system. The reason 
for the use of the wave action devices is simple and purely mechanical. 
Parabolic antennae hardly achieve gains much above 40 dB. Furthermore, at 
this level they are already enormous. For 7.5 GHz, a 15 foot parabola has 
a 48.5 dB gain. To increase this gain by just 3 dB, the parabola diameter 
has to be increased to 21 feet, and so on. As the diameter increases, the 
price of the antenna increases exponentially. 
If an actual back-to-back system were to be used, parabolic antennae having 
diameters greater than 60 feet would be required, since G=61.25 dB for f=8 
GHz. This assumes that a 55% efficiency can be maintained for all 
diameters, which is a difficult proposition. In addition, the supporting 
structure for complying with the rigidity requirements of such a system 
would be considerable. The same problems and hardships facing the 
back-to-back system would have to be faced by a reflector system of the 
billboard type. The reflector would have to be huge, to maintain its 
surface flatness, regardless of conditions, and would have to satisfy 
tremendous structure rigidity requirements. 
None of the aforedescribed difficulties would affect the wave action 
devices of the invention. Operating under interference principles, the 
wave action devices avoid all the mechanical problems which must be 
resolved by parabolic antennae and billboard reflectors. Furthermore, the 
wave action devices of the invention have two technical advantages over 
parabolic back-to-back antennae, billboard reflectors, and even active 
repeaters. The first advantage is that the wave action device of the 
invention provides virtual independence of the K factor for the link due 
to its multiple "knife-edge" nature. The second advantage is the 
non-rigidity requirements for the supporting structure of the wave action 
device. The device may be placed high up. A billboard reflector or large 
parabolic antennae cannot be placed high up. The wave action device thus 
offers a flexibility for the solution of link problems which the 
reflectors and parabolic antennae do not. 
The dimensioning and positioning of the blades and the K control feature of 
the wave action device must be determined. The Example is schematically 
shown in FIG. 24. The wave action device will have several blades. The 
vertical dimensions of the blades may be determined to a first 
approximation as follows, and as shown in FIG. 25. 
The set of blades defines a set of apertures. The first aperture is between 
the ground and the lower edge of the lowest blade. The last aperture is 
all of the space above the upper edge of the highest blade. The other 
apetures of the set are those between the upper edge of any one blade and 
the lower edge of the blade immediately above it. 
Since the transmitter T is sufficiently far away, the wave front will be 
essentially planar and the phase shift from one aperture to the next will 
be 
##EQU7## 
The wave action device will radiate into the semi-space Z&gt;0, at an angle 
.theta. with the y axis. As well known from the theory of linear antenna 
arrays, there will be a family of equal amplitude lobes defined by 
##EQU8## 
wherein K=0, .+-.1, .+-.2, . . . , d is the constant space separation 
between consecutive elements and .DELTA..phi. is the constant phase 
separation between consecutive elements. In the present case, d=2a and 
.DELTA..phi..about.(2.pi./.lambda.) 2a sin .theta..sub.1. The lobes will 
be duly modified by the radiation pattern of each single aperture, but it 
is possible to produce a very sizeable lobe directed towards R by 
judiciously selecting the parameter "a". In particular, by selecting 
##EQU9## 
it follows from Equation (9) that 
##EQU10## 
The lobe that will reach R is defined by K=-1. That is 
##EQU11## 
since Equation (11) then becomes 
##EQU12## 
This is the direction towards R as seen from the wave action device. 
All lobes may be intensified by simply increasing the number of apertures. 
This is due to the fact that the power supply to the array is just the 
incident wavefront originating from the transmitter T, so that the 
increase in the number of apertures will not decrease the magnitude of 
power supplied to each one of them. The increase is defined as 20 log N 
(powerwise). The lobe reaching R can therefore be as intense as desired. 
The wave action device redirects the beam and provides gain. 
The width of the blades and the spaces between them will thus be 
approximately 
##EQU13## 
With this data and the previous data results, the device may be easily 
constructed by anyone ordinarily skilled in the art. 
The influence of the variations in atmospheric refractivity, described in 
telecommunications as the K factor variation, is indicated by variations 
in the parameter b (FIG. 24), which is the measure of the Earth bulge. 
The dimension b in meters is determined by 
##EQU14## 
wherein b is in meters and d.sub.1 and d.sub.2 are in kilometers. It 
follows that 
##EQU15## 
These values directly influence the measure of the obstruction. In the 
Example, it is stated for what value of K the 1000 m obstruction occurs. 
It is assumed that it was for K=4/3. Hence for K=1/3 the obstruction will 
become 1000+36=1036 m. This is a 3.6% increase, and will hardly affect the 
dimensions of the wave action device. 
The situation is the basis for one of the techniques for the control of K 
by the wave action device. The wave action device of the invention should 
be installed at such an altitude as to make the b, and therefore the K, 
variations negligible. The local topography may not be suitable for this. 
In such case, there are several possible recourses. 
One solution is the use of high towers. If, for example, the topography 
were completely smooth, which would be the worst case, the following 
artifice would be used. The wave action device would be placed off the 
direct line interconnecting the stations by 1 km, for example. The blades 
of the wave action device would be positioned conveniently inclined so 
that the plane formed by the line interconnecting the transmitting and 
receiving stations T and R, respectively, and the signal waves to the 
device from these stations, which originally was vertical, is then 
inclined. The blades remain perpendicular to this plane in its new 
position and are therefore inclined. In this manner, the 1000 m 
obstruction is again simulated and the original situation may be 
recreated. However, care must be used in determining minimum tower 
heights. There are also other considerations pertinent exclusively to 
radio transmission engineering, as illustrated in FIGS. 26a and 26b. 
In the off-line of sight situation only the y component of the 1000 m 
obstruction would be influenced by K, and it would be very easy to select 
the point D' so that y&lt;&lt;1000 (FIG. 26a). Hence, in this sense, this is an 
even more favorable situation. 
There are still other ways to make the wave action device of the invention 
rather insensitive to the K factor. One method is to design a set of 
blades for a value of K, another set for another value of K, and so on. 
For a discrete set of Ks covering a given range such as, for example, 
K=4/3 to K=5/8 a total radiation pattern would be provided which would 
always reach the receiver R and always be reached by the transmitter T. 
The analogy to optics is found in the bifocal, trifocal, etc., lenses. 
The last technique may provide a wave action device which is too large. An 
alternate method is to use more than one antenna at the receiver R, the 
transmitter T, or both. Thus, the obstruction .DELTA.H remains the same 
for K.sub.1 and K.sub.2 if the proper pair of antennae is considered, as 
shown in FIG. 27. This technique may be generalized to use more than two 
antennae. It may also be combined with the aforedescribed techniques. 
In addition to the K control techniques, it is observed that if the wave 
action device is constructed of only one blade, conveniently long and 
properly shaped, it will act, in addition to the aforedescribed 
characteristics, as a "knife-edge". As a "knife-edge", the wave action 
device intrinsically renders the link essentially independent of 
variations in the K factor, as hereinafter described. 
The wave action device of the invention wil stabilize the beam with respect 
to fluctuations in the refractive index. It has been explained in the 
Example how insensitivity to K fluctuations could be achieved. 
Furthermore, the one blade configuration of the wave action device has an 
intrinsic K stabilizing feature due to its "knife-edge" nature, regardless 
of its length. This is hereinafter clarified. The operation of the wave 
action device of the invention may be supported by a generalization of the 
"knife-edge" theory. 
The K-stabilization of a microwave beam by use of a "knife-edge" shaped 
obstacle is most readily seen from the loss versus clearance curves shown 
in FIG. 28. The CCITT curves of FIG. 28 portray three types of obstacle 
geometry. These are the "knife-edge", the flat obstacle or "plane Earth" 
and the round smooth type or smooth sphere diffraction. The abscissa 
represents the clearance and the ordinate represents the free space loss. 
The curves of FIG. 28 indicate that the influence of the K variation, which 
implies a variation of the clearance over the obstacle, will have quite a 
different impact, depending upon which curve is being followed. It is also 
obvious that the "knife-edge" curve is the most stable one. Hence for a K 
variation which causes a clearance variation from F/F.sub.1 =1 to 
F/F.sub.1 =0, the "knife-edge" curve shows a loss of only 6 dB, against a 
loss of 22 dB for the smooth sphere diffraction and total disappearance of 
the signal for the plane Earth theory. 
Athough the curves of FIG. 28 are widely and traditionally well known and 
are published by the CCITT, they are used just to estimate obstruction 
loss by existing natural obstacle. An artificial structure is installed 
over a natural obstacle to form a single obstacle with a "knife-edge" 
nature thereby attaining the aforementioned K-stability. 
The classical theory of "knife-edge" diffraction is well known, and is 
found in many standard texts on optics. This theory may be generalized for 
the situation shown in FIG. 29. FIG. 29 represents a diffractor in its 
simplest geometry. In this case, the diffractor functions as a multitude 
of "knife-edges". 
If P.sub.T is the transmitted power and G.sub.T is the transmitter antenna 
gain, 
##EQU16## 
The field at the receiver E.sub.R is then calculated by 
##EQU17## 
The received power P.sub.R at the receiver R.sub.X is then given by 
##EQU18## 
It is observed that 
##EQU19## 
which is the link free space loss. 
##EQU20## 
which is the radius of the first Fresnel zone. 
Hence, the attenuation factor for the diffractor served link will be 
##EQU21## 
wherein C and S are the classical Fresnel integrals. 
Hence 
##EQU22## 
The link attenuation is thus described as the attenuation caused by the 
knife-edge, which is .alpha. knife-edge, modified by a factor G.sub.D, 
which may be called the diffractor's gain with respect to the knife-edge. 
The integral 
##EQU23## 
corresponds in FIG. 29 to the evaluation of 
##EQU24## 
The second factor is the summation of all the windows of the diffractor. 
This is the connection to the knife-edge theory. The first factor is the 
antenna array factor. This is the connection to the theory of the 
diffractor considered as a particular antenna array. 
The devices of Kock, U.S. Pat. No. 2,577,619 are not knife-edge devices and 
cannot provide the K stabilization feature. 
The particular positioning and spacing of a particular disclosed embodiment 
of the wave action device of the invention permits its operation as an 
electromagnetic lens at a location which is remote from the source of the 
beam. The devices of the aforedescribed Kock patent cannot be used for 
this purpose. The embodiment of the wave action device discussed with 
regard to the Example functions as an electromagnetic lens. This is due to 
the fact that the selective and appropriate blockage of parts of the 
incident beam by the wave action device is tantamount to changing the 
local phase of points in a wave front. 
As hereinbefore described, the appropriateness of the blocking is 
established by the particular positioning and spacing of the blades. In 
accordance with the general wave theorem of Huyghens, as formulated by 
Kirchhoff, this redirects the beam and provides focussing. All 
electromagnetic lenses may be developed entirely from one or another 
version of Huyghens-Kirchhoff's theorem. The wave action device of the 
invention thus operates as an electromagnetic lens. 
The wave action device of the invention functions as an electromagnetic 
lens despite its remoteness from the source of the beam. Actually, it is 
under this condition that the embodiment of the wave action device 
discussed with regard to the Example operates. The theory for this remote 
situation is most clearly illustrated in FIGS. 30 and 31. 
As shown in FIGS. 30 and 31, the wave action device is installed over the 
obstacle at a site remote from the source A of the beam. The sphere E is a 
wave front which strikes the obstacle, and eventually the wave action 
device, as shown in FIG. 30. The phase .theta. of the wave of the sphere 
is constant. However, in the plane .SIGMA., defined by z=0, the phase is 
by not at all constant (FIG. 30). In fact, if the point B is understood to 
be the zero value reference phase, the phase distribution along x, in the 
plane .SIGMA., is defined as 
##EQU25## 
wherein k=2 .pi./.lambda., .lambda. is the wavelength, and the time 
variation of the wave field is assumed to be exponential (i wt) with 
.omega.=2.pi.c/.lambda., c being the speed of propagation of the wave and 
i=+(-1).sup.1/2. 
It is thus clear that the phase distribution in the plane .SIGMA. being as 
hereinbefore described, all possible phases of interest are available in 
said plane. if .SIGMA. were a metal screen the entire signal would be 
blocked. This could be considered as a complete equalization of the phases 
of the wave field, which would incidentally have zero intensity. However, 
if suitably located and dimensioned windows were to be opened in .SIGMA., 
they would establish over .SIGMA. a surface with a desired phase 
distribution as well as an amplitude distribution, essentially unaffected 
at the window spaces, and with zero value at the metal blocking blades. 
This situation according to Huyghen's theorem, as modified by 
Kirchhoff-Fresnel, permits the beam to be redirected to any preselected 
direction. Since the intensity of the redirected beam is dependent upon 
the number of windows, or spaces defined by the blades, the beam intensity 
may also be controlled. In this manner, both redirectioning and gain, or 
focussing, are obtained. The wave action device of the invention thus 
functions as an electromagnetic lens at a location which is remote from 
the source of the beam. 
The devices of the aforedescribed Kock patent, like any other 
electromagnetic lens, as hereinbefore discussed, operate by introducing 
local changes of phase in a wave front by the use of natural and/or 
artificial dielectric material and/or waveguide collections properly 
shaped and positioned in space. The devices of the aforedescribed Kock 
patent do not operate on blockage, unless this is considered to be but a 
limiting and drastic form of local phase modification, and, primarily are 
not at all suitable to operate at sites remote from the source of the 
beam. This is due to the following reasons. First, the structure of the 
Kock device would be very large and impractical. Second, the phase 
modification technique of Kock consists of having different parts of the 
wave front travel along different lengths, not through different widths, 
of his lens. The lengths are then critically dimensioned. This is not 
feasible at a remote site location where imprecision in the determination 
of all the distances would obviate any and all precision requirements for 
the lengths of the Kock device. In contradistinction, the critical 
parameter of the wave action device of the invention is the width and 
spacing of the blades. These are measurements taken transversely to the 
direction of the wave propagation, and not alongside it. This permits 
precise dimensions to be established for remote locations of the wave 
action device. This fact permits the feasibility of the aforedescribed 
theory. 
The wave action device of the invention may be constructed to balance 
variations in refractive conditions in the atmosphere, usually described 
in telecommunications as the K factor of connection of Earth's curvature, 
which will vary the equivalent relative position of the wave action device 
with respect to the end terminal stations. The devices of the 
aforedescribed Kock patent cannot balance such variations. In fact, Kock 
did not have to face this problem, since his lenses are installed very 
near the source of the beam and form a single complex with said beam. Kock 
did not consider the problem of designing remotely installed lenses. 
FIG. 32 illustrates how serious the problem of defocussing can be. In FIG. 
32, the source A.sub.1 of the signal is an antenna and the receiver 
A.sub.2 is an antenna. The wave action device D is halfway between the 
antenna A.sub.1 and the antenna A.sub.2. 
The bulge b of the Earth's curvature, shown in FIG. 32, is defined as 
##EQU26## 
Since K ranges typically from 1/3 to 4/3 or above, 
##EQU27## 
This may not seem to be much, but in wavelengths it is a sizeable change. 
This is shown by 
##EQU28## 
For f=7.500 GHz, corresponding to .lambda..about.0.04 m, this length 
difference would correspond to a continuous phase variation of 
##EQU29## 
This may be controlled by specially incorporated features of the wave 
action device of the invention, as hereinbefore described. It would be 
very difficult, if not impossible, to extend these techniques to the 
devices of the aforedescribed Kock patent. This has not yet been done. 
The invention is by no means restricted to the aforementioned details which 
are described only as examples; they may vary within the framework of the 
invention, as defined in the following claims. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in the above constructions without 
departing from the spirit and scope of the invention, it is intended that 
all matter contained in the above description or shown in the accompanying 
drawings shall be interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein 
described, and all statements of the scope of the invention which, as a 
matter of language, might be said to fall therebetween.