[0001] This invention is concerned with a telescopic pole, particularly for holding antennas
for electromagnetic signals at a considerable height from the ground, and more particularly
antennas for measuring television signals in the field. However, the invention could
foreseeably find other applications, whenever it is required to temporarily position
objects at a height of a few tens of meters from the ground.
[0002] As known, in carrying out measurings of electromagnetic signals in the field, particularly
television signals, the pick-up antenna is required to be positioned at a considerable
height from the ground, e.g. at 10 to 20 meters height, in order to prevent any ground
effect from attenuating the signal or affecting the measure in any way. This was achieved
in the past by using existing landmarks such as towers, buildings and the like, with
considerable inconvenience and delay for transfer and assembly of the instruments
in the desired location. Moreover, the landmark was not always available, and it was
not always possible to obtain the right of accessing it.
[0003] The main object of the invention is therefore to provide a preferably revolving telescopic
pole, particularly for measuring electromagnetic signals in the field, more particularly
for measuring television signals, which can be installed aboard a vehicle to be taken
to the site and be quickly raised in a self-contained structure, thus dispensing
with the need for existing buildings or structures.
[0004] The above object is achieved by the invention, together with other objects and advantages
such as will appear from the following description, with a telescopic pole, particularly
for holding TV antennas in the field, characterized in that it comprises a set of
similar tubular elements having decreasing cross-sections and lengths, closed at the
bottom and each provided with a pair of turning, idle rollers journaled at their tops
on opposite walls, each tubular element being contained within the next bigger one,
in such a way that successive tubular elements are alternately arranged with axes
orthogonal to each other, and the entire set of tubular elements being contained within
a tubular frame, each tubular element having a flexible ribbon attached at its ends
to the tops of opposite walls not journaling the rollers, each ribbon passing over
the rollers of the next inward tubular element and under the closed end of the further
tubular element, with lifting means for lifting the most external of said tubular
elements with respect to the tubular frame.
[0005] The invention will now be described in more detail with reference to a preferred
embodiment, shown in the attached drawings, which are given by way of illustration
and not of limitation, and in which:
Fig. 1 is a front view, in elevation, of a telescopic pole according to the preferred
embodiment of the invention, in collapsed condition, and installed on a partly shown
motor van;
Fig. 2 is a back view, in elevation, of the telescopi pole of Fig. 1, in collapsed
condition;
Fig. 3 is a view in transverse cross-section, across line III-III of Fig. 1, on an
enlarged scale;
Fig. 4 is an elevation view, partly broken, of the terminal portion of the telescopic
unit of the pole of Fig. 1; and
Fig. 5 is a view in vertical cross-section, of three adjacent tubular elements belonging
to the telescopic pole of Figg. 1 to 4.
[0006] With reference to Figg. 1 to 3, 10 and 12 indicate the floor and the roof, respectively,
of a conventional motor van. Under the floor 10 is attached a cage 14, in alignment
with an opening in the floor. A trap 15 in roof 12 is vertically aligned with cage
14, the trap being closed by a removable door 16. A cylindrical barrel 18 extends
downwardly from the roof, coaxially with trap 15 and with cage 14.
[0007] In the bottom of cage 14 is centrally held a thrust bearing 19, forming a pivot for
the bottom end of a tubular frame 22, of square cross-section, vertically extending
through barrel 18 and into the trap 15. In tubular frame 22 a disc 24 is attached
coaxially, near the bottom edge of barrel 18. Around the periphery of disc 24, four
evenly spaced, free rollers 26 stand with axes parallel to tubular frame 22, and are
arranged for rolling against the inner surface of barrel 18, thus keeping tubular
frame 22 in vertical position and freely revolving.
[0008] Disc 24 has a peripheral groove which accommodates a transmission belt 28 driven
by a driving pulley 30, which is driven in its turn by a reversible electric motor
32 mounted on barrel 18. By operating motor 32, it is thus possible to change at will
the rotation angle of tubular frame 22.
[0009] A vertical plate 34 is mounted on tubular frame 22, carrying an electric motor 36
with an associated reduction gear 38. A toothed gear 40 with horizontal axis is keyed
on reduction gear 38, which drives in its turn two satellite toothed wheels 42, 44,
carrying integrally respective winder spools 46, 48, extending on the back of vertical
plate 34, and whose purpose will be described below.
[0010] With reference to Figg. 4 and 5, a set of similar tubular elements 50, 52, 54, ...,
56 are contained within tubular frame 22, which are also square and have progressively
decreasing cross-sections and lengths, one within the other in sequence. Each tubular
element is closed at the bottom and is open at the top, where it carries two vertical
parallel plates such as 58, 60, which are attached on two opposite walls. Two symmetrical,
idle rollers such as 62, 64 are journaled between plates 58, 60 with horizontal axes.
The arrangement of plates 58, 60, and therefore also of rollers 62, 64, is shifted
of 90° around the pole axis as one goes from each tubular element to the next, i.
e. the rollers of two adjacent tubular elements are orthogonal to each other, and
consequently the rollers of alternate tubular elements are parallel to each other.
[0011] To each tubular element a flexible ribbon such as 66 is associated, which passes
under the closed bottom end of the tubular element, over the respective idle rollers
of the outwardly adjacent tubular element, and is attached with its opposite ends
to the top of the outwardly next tubular element, as seen most clearly in Fig. 5,
where only one ribbon is symbolically shown in broken line for the sake of clarity.
The alternate arrangement of the rollers allows the above ribbon connections to take
place without interference.
[0012] Tubular frame 22 also has two idle rollers, and ribbon 68, which is associated with
the most outward tubular element, passes over these rollers and is directed to the
winder spools at the foot of the tubular frame.
[0013] When motor 36 is started, both ends of ribbon 68 are wound on winder spools 46, 48,
and ribbon 68 therefore lifts the most outward tubular element. Consequently, the
idle rollers of the adjacent tubular element push against the next ribbon, whose ends
are attached to the top of the tubular frame. Therefore this ribbon, as will be best
understood by looking at Fig. 5, will also pull the next tubular element upwards,
and the lifting motion will be propagated down to the last tubular element 56.
[0014] For operation, an antenna or other desired object (not shown in the Figures) is attached
to the top of the most internal tubular element. The vehicle in which the telescopic
pole is installed is made rigid in horizontal position with respect to the ground
by means of jacks, not shown and beyond the scope of the invention. Motor 36 is the
operated to raise the pole as described above. The antenna may be connected to a cable
70 passing through a hole 72 in disc 24 and is wound to a spool 74 rotatably mounted
on plate 34 and driven by the same lifting motor 36 through a friction clutch 76 known
per se, so that spool 74 unwinds the cable as the pole extends, and winds up the cable
as the pole is collapsed. A distributor member 78, also known per se, is driven by
the same friction clutch, through a screw not shown, to evenly distribute the cable
on spool 74.
[0015] The pole can be revolved around its vertical axis, for azimuthal orienting of the
antenna, both in its extended and its collapsed condition, by operating motor 32,
or by hand.
[0016] The vehicle will usually accommodate instrumentation connected to cable 70, and possibly
adapted to control motors 32 and 36.
[0017] From the above disclosure it can be seen that the pole has an extremely compact and
lightweight structure, in which the means for propagating the motion from one tubular
element to the next comprise in practice only the flexible ribbons. Consequently,
the telescopic pole, while being lightweight and compact enough for installation in
a vehicle such as a motor van, is nonetheless able to reach considerable heights when
extended, e. g. 20 to 30 meters from ground, and to be azimuthally oriented even while
extended, by very simple means. Furhter, the pole, due to its high symmetry, maintains
an extremely linear and vertical attitude, provided that the stability of the supporting
vehicle has been assured.
[0018] A preferred embodiment of the invention has been described, but it is understood
that the invention also encompasses equivalent changes and modifications, obvious
for the person skilled in the art, falling within the inventive concept. For instance,
for applications where the azimuthal oientation is not required, the frame can be
rigidly fixed to the supporting structure; or the winder spools at the foot of the
frame can be driven by different means, equivalent to those shown; also, the cable
winder spools could be dispensed with, e. g. in applications different from an antenna
for electromagnetic measures; the number and lengths of tubular elements may vary
according to circumstances. All of these and other modifications should be regarded
as falling within the scope of the invention.
1. A telescopic pole, particularly for holding TV antennas in the field, characterized
in that it comprises a set of similar tubular elements (50, 52, 54, ..., 56) having
decreasing cross-sections and lengths, closed at the bottom and each provided with
a pair of turning, idle rollers (62, 64) journaled at their tops on opposite walls,
each tubular element being contained within the next bigger one, in such a way that
successive tubular elements are alternately arranged with axes orthogonal to each
other, and the entire set of tubular elements being contained within a tubular frame
(22), each tubular element having a flexible ribbon (66) attached at its ends to the
tops of opposite walls not journaling the rollers, each ribbon passing over the rollers
of the next inward tubular element and under the closed end of the further tubular
element, with lifting means (36-48) for lifting the most external of said tubular
elements with respect to the tubular frame.
2. The telescopic pole of claim 1, characterized in that each of said tubular elements
is square in cross-section.
3. The telescopic pole of claim 1 or 2, characterized in that said lifting means (36-48)
comprise a further flexible ribbon (68) passing under the most external tubular element,
over two rotatable rollers journaled at the top of two opposite side walls of the
tubular frame, and with its ends attached to winder means (46, 48) mounted on opposite
sides of the tubular frame.
4. The telescopic pole of claim 1, 2 or 3, characterized in that said tubular frame
is rotatably supported in a vertical position.
5. The telescopic pole of claim 4, characterized in that said tubular frame is rotatably
rests on a thrust bearing (19), and is laterally guided by idle rollers 26) running
on the internal surface of a cylindrical barrel (18) coaxial with the thrust bearing.