Communications Towers and Masts 1940s to 1970s.
Most of the
towers and masts used by the RAF were erected by the Works Services department
of the Ministry of Works (1943 to 1962) or Ministry of Public Buildings and
Works (1962 to 1970) or by civilian contractors on their behalf. These include
the standard 88 ft. and 118 ft. guyed
metal poles and the standard 70 ft., 90ft. and 120 ft. self-supporting wooden
lattice towers. The Works Services (MPBW) was responsible for the erection,
maintenance and dismantling of these types of aerial support.
to these Works Services towers and masts the following types of mast were the
most commonly used ones and were erected, maintained and dismantled by aerial
erectors. The mast Type 23 was a 78 ft. guyed metal mast consisting of three
cigar-shaped sections. The mast Type 32 was a 105 ft. guyed wooden lattice
mast. The mast Type 34 was a 52 ft. guyed metal mast similar to the mast Type
23 except it consisting of two cigar-shaped sections and the mast Type 35A which
was a 97 ft. guyed metal mast consisting of three cigar-shaped sections.
There were also a number of much smaller guyed and free standing masts used by
mobile radio and radar units to support aerial arrays.
In the 1960s several
projects were undertaken using 100 ft. lattice steel towers such as the
construction of a aerial farm at the Joint Services Headquarters at RAF Episkopi
in Cyprus. The steel towers were erected by the Royal Engineers and the
aerial arrays and feeder systems were installed by a joint fitting party
consisting of Royal Signals aerial erectors from Blandford and aerial erectors
from the RAF's Radio Engineering Unit.
Several aerial farms using lattice
steel towers were also constructed overseas by civilian contractors, such as
the aerial farm, seen below, which was built in the sea at RAF Muharraq in
23 and Mast Type 34.
The mast Type
23 had three 26 ft. cigar-shaped members coupled together end to end by
special joints giving a height of 78 ft. The mast Type 34 had two 26 ft.
cigar-shaped members coupled together in the same manner giving a height of
52 ft. Each cigar is comprised of tapering tubular sections which are joined
together by fitting one into the other, the resulting joint being rigid, due
to the tapering fit.
Both types of mast were mounted on a steel base plate.
Both types of mast were held upright by flexible steel wire rope guys, 4 upper,
4 middle and 4 lower guys for a mast type 23 and 4 upper and 4 lower guys for a
type 34 mast. The guy ropes were anchored to "T" shaped pickets driven into the
ground 27 ft. 6ins. from the base plate. In loose or sandy soils the pickets
were often concreted into the ground. The guy ropes were adjusted by means of a
pair of Astral nuts.
The crown coupling of the mast was fitted with a swivel
hooked plate to which a backstay and a halyard pulley block could be fitted.
Another variation of the crown coupling had a special welded plate in place of
the swivel hook to which a spreader for a Type 412 VHF aerial system could be
The derrick for raising the mast consisted of one cigar-shaped
member identical with those used in the mast and was fitted to the base plate
by a trunnion bridge.
The total ground space required to erect a mast Type 23
was 120 ft X 60 ft. and 90 ft. x 60 ft. for a mast Type 34. A team of six aerial
erectors was required to erect a mast.
There are four mast Type 34s to be seen in the old photograph
above taken in 1963 at RAF Riyan near Mukalla in the Hadhramaut (now a part of
South Yemen). The mast on
the far left and the one on the far right are supporting a triatic which has
several 1/4 wave vertical aerials suspended from it. There two more mast Type
34s in the centre of the picture which are both supporting spreaders. The left
hand mast has one UHF Type 41 aerial at the right hand end of the spreader and two
Type 41s at the other end, one of which is mounted upside down. The other mast
has a Type 24 VHF aerial at each end. There are also two shorter wooden poles
near to the control tower, one is supporting a wind speed gauge and the other a
Mast Type 32.
The mast type 32 was a wooden lattice, sectional 105ft guyed mast originally
manufactured during the 2nd World War for use by mobile radio and radar units
in the United Kingdom and overseas.
The mast comprised of six short sections
which could be fitted one inside another for transportation on special
four-wheeled trailers. Each trailer had a winch fitted at one end and it was
used to raise and lower the mast once it was removed from the trailer and
assembled. The mast trailers were usually towed by the radio or radar vehicles
when moving from one site to another site. Being made mostly of wood they
were light in weight and were relatively easy to repair.
After the war many
were used on permanent sites and over time were replaced by steel masts.
Several type 32 masts can be seen above in the aerial farm photograph
(thought to be Chicksands) taken in the 1950s. The two riggers are working on
the nearest mast and the six sections of the mast are clearly visible.
In 1957 one (nicknamed "Snow White" for some obscure reason) was still in use
at RAF Gangodawila in Ceylon and was destroyed when the camp closed down (see
the places page).
Several were still in use at RAF Chicksands, an out-station of the RAF Signals
Centre at Stanbridge, about the same time.
There was also one at the Aerial Erector School, RAF Chigwell in 1956 and
it was lowered and dismantled and transported on its trailer to RAF Norton
when the Aerial Erector School moved there in October 1956. It remained there,
still loaded on its trailer, parked on the aerial farm until the school moved
to RAF Digby in September 1959. The trailer was serviced and fitted with new
tyres for the move to Digby and was again parked on the aerial farm. It is
thought that the mast sections were later found to be rotten and beyond
economical repair. As it was no longer required as a training aid and the masts
were being phased out of service, the whole thing was scrapped.
A Mast Type 32
fitted with a set of GEE Aerials about to be raised at the Radio Engineering
Unit, RAF Henlow.
The mast type 32
seen above was one of several which were refurbished at the Radio Engineering
Unit at RAF Henlow and were used for a series of experiments using the GEE
carried out by the boffins from 90 Group HQ in the early 1950s.
No example of a Mast Type 32 is now known to exist.
Aerial / Mast Vertical 20ft and 34ft Steel.
This aerial/mast was designed and manufactured in Canada for the Canadian
Department of National Defence in 1943 for use in the field. Large numbers
of the kits were used by the British Army and the Royal Air Force by mobile
radio and radar units.
The Aerial Kit consisted of two telescopic masts
which could be used as vertical aerials or as masts to support a horizontal
aerial. The kit came in a large canvas carrying bag with all the necessary
parts, one 34ft mast, one 20ft mast, aerial base, vehicle roof mounting base
plate, vehicle mounting brackets (with hardware), ground spikes, guys, aerial
rods and hammers. The 34ft mast had 6 telescopic steel tubular sections and
the 20ft mast 4 telescopic sections, the extended sections were locked into
place with a locking collar. When erecting the mast the sections were extended
and locked one by one starting with the smallest section.
Vertical Aerial mounted on vehicle roof.
Aerial on a Vehicle. The normal use of the 34ft vertical
aerial was on a vehicle roof using the vehicle roof base plate. The aerial
had to be guyed.
Erecting a vertical aerial on roof of a vehicle.
The Vertical Aerials could be used for a ground station by mounting the mast on
a ground spike. The 20ft vertical mast could also be used as a vertical aerial
by inserting 4 aerial rods (type F) in the spring adaptor at the top, thereby
forming a 36ft aerial. It could be erected on the vehicle roof or on the ground.
The 20ft aerial could also be used as a vertical aerial but the advantage over
a normal vehicle whip aerial was small.
and Vertical Aerial installation for Ground Station.
aerial or mast on the ground.
Both the 34ft and 20ft vertical aerials could be used for
supporting a horizontal aerial. The horizontal aerial was insulated from the
vertical aerial mast.
Aerial installation for a Vehicle Station.
The use of these excellent
small lightweight Aerial/Masts in the Royal Air Force continued right through
the 1950s and well into the 1960s.
"Wulfel" 110ft Aerial Mast.
This type of
mobile radio relay aerial mast was inherited from the German Armed Forces and
was in use by the 2nd Tactical Air Force in the Europe in the 1950s.These
mobile masts were a part of the German "Pintch" radio relay system and the whole
system was adopted by the RAF. Ground Wireless fitters and mechanics were
re-trained to maintain and operate this system at RAF Sundern in Germany. These
fitters and mechanics were also given training on the operation of the masts and
assisted the aerial erectors when raising the masts. The system usually
operated over a point to point distance of approximately 40 miles between units.
The 3 sectioned 110ft mast was fitted onto a Mercedes lorry chassis and was
raised hydraulically. The mast and vehicle weighed about 30 tons. The mast was
lowered and folded in two on the back of the lorry when being moved from one
location to another location.
Once the lorry was parked in the required
position the six stabilizing jacks were lowered on to the ground. Three guy
anchorage boxes were then placed into position, filled with sand bags and the guy
winches mounted on top of the boxes. The triangular base plate was lowered down
from the rear of the lorry ready for the base of the mast to be located onto it.
The the two aerial arrays with their stablizer plates and three guy ropes attached
The mast was then hydraulically raised and the release of the guy ropes was
controlled using the three winches.
Once the mast was fully erected the aerials
were connected to a radio vehicle by co-axial cables. The aerials could be rotated
and tilted up and down to get the best possible signal by electric motors. A
mobile generator provided the electrical power for the unit.
In the photograph
above the mast can be seen folded up on the lorry ready to move off. The
triangular base plate is hanging from the rear end of the lorry and the
hydraulic ram used to raise the mast into the vertical position is in the centre
of the lorry. A row of spades used to fill the sand bags or level up the ground,
jerry cans to carry extra fuel and the drums of co-axial cable can also be seen.
Aerial Rigger John Holmes is
leaning on the lorry beside one of the stabilizing jack base plates of the lorry
at the Radio Relay Unit, RAF Wahn near Cologne.
the photograph above, taken during a field training exercise somewhere in West
Germany, the mast is fully assembled ready to be raised to the vertical position
and be located onto the base plate. Once the mast is in place on the base plate it
is then hydraulically raised to its full height of 110ft. The two co-axial cable
drums are also in position on the rear of the lorry ready to release the cables
as the mast rises.
Ex Aerial Erector John Holmes kindly gave his permission
to use these photographs taken in 1957. Much useful information about the "Pintch"
system was provided by Ex-Ground Wireless mechanic Fred Flight.
Klockner 30/40ft Mast.
A small 30ft-40ft telescopic mast inherited from the
German Army, raised by a series of wires and pulleys. In the photograph above
aerial erector Pete Burgess is fitting the upper guy ropes into place on the top
of the mast prior to
a successful erection. The photograph was taken during Exercise Schnell Zug in
the Eiffel forest about 3 hours drive from the Rheindahlen HQ in the summer of
Mast Type 35A.
mid-50s the mast was one of several types of mast adopted by the RAF
for use when building some of the temporary HF transmitter and receiver
facilities overseas which were required during the relocation of RAF bases
caused by the rundown of the British
The mast was originally designed and manufactured for use by
the Royal Signals in the 1940s and could be assembled to give three
different heights, 92ft, 97ft and 102ft. The 97ft variation of the mast
was the model used by the RAF and was renamed "Mast Type 35A".
was comprised of three main cigar-shaped members, coupled to each other
by means of a universal joint and was held upright by guyed wires. Each
cigar was comprised of four tapering tubular sections plus a central
tubular section (Spigot) which was tapered at both ends. The sections were
fitted one into the other to form the cigar, the resulting joints were
held rigid due to the tapered fit. Different sized spigots were used to
achieve the various mast heights.
A partly assembled cigar-shaped mast section.
derrick for hoisting the mast consisted of one cigar-shaped member identical
with those used for the mast. The feature which was new to the RAF riggers
used to erecting guyed masts was the universal joint employed at the point
where the cigar sections were coupled together. This flexible joint
necessitated the use of check ropes when raising or lowering the mast, to
prevent it from buckling or falling towards the derrick, otherwise the
procedure was in accordance with the normal practice used in the erection of
Masts Type 23 and Type 34.
permanent installations and on sites where the soil was light or sandy, the
excavated guy anchorage holes were often filled with concrete.
A diagram of a Mast Type 35A being erected showing the
positioning of the erection crew and the back guy check ropes.
As can be
seen from the diagram above technically there should be 14 personnel in the
erection team but these masts were often erected with far less personnel.
It was very rare for there to be more than eight or nine riggers in a fitting
party and frequently other members of a fitting party were co-opted to assist
in erection phase of aerial farm construction.
RAF MF and
HF Aerials 1940s to 1970s.
matched Horizontal Single Wire Half-wave Dipole.
A horizontal single wire aerial had an impedance of 70 ohms
but it was not practical to build 70 ohm open wire feeder systems. The problem
was overcome by "fanning" the upper part of the down feed as seen above thus
enabling the aerial to be connected to the RAF standard 600 ohm open wire
feeder systems. The horizontal element was constructed using 300lb per mile
copper wire and down feed and feeder line using 100lb per mile copper wire.
The junctions of the element with the down feed could be soldered if there
were no Splay Junctions available.
Three-wire Folded Half-wave Dipole.
The three-wire folded dipole was
used by the RAF as both a receiving and transmitting aerial. The band width
is greater than that of a single-wire dipole due to the greater cross-sectional
area of the aerial which resulted from the folding. The folded dipole had a
greater capacitance and less inductance per unit length than the basic dipole.
This type of folded dipole can be regarded as a normal dipole with an extra
half wavelength of wire added on to each end, these extra lengths being folded
back parallel with the centre portion to form three closely spaced parallel
dipoles. The current standing waves in the three portions are in phase and the
radiated waves reinforce each other. The feed impedance of the aerial is about
600 ohms and thus could be connected to the standard open wire feeder systems.
The aerial elements were constructed using 100lb per mile copper wire.
Construction and rigging details of a Three-wire Folded
Eight-wire Cage Full-wave Dipole Aerial.
The eight-wire cage full-wave dipole
aerial was widely used by the RAF for both transmitting and receiving. The
cage form of the aerial gave it a greater bandwidth than a single wire aerial
and also gave it a greater power handling capability. Its feed impedance of
about 600 ohms enabled it to be connected to the standard RAF open wire
feeder systems. The aerial elements were constructed using 100lb per mile
Construction and rigging details of a Eight-wire Cage Dipole
Eight-wire Cage Quadrant Aerial.
The eight-wire cage quadrant
aerial was simply a standard eight-wire cage dipole which was bent at the
centre until the two halves are at right angles. This action changes the
aerial from a directional aerial into an omni-directional aerial. Its feed
impedance remained the same at 600 ohms. The two quadrant cages were
constructed at slightly less than a half-wave long using 100lb per mile
Construction and rigging details of a Eight-wire
Cage Quadrant Aerial.
Type, Two-wire MF Aerial.
An inverted "L"
aerial was a special type of vertical aerial in which the upper part of the
wire is bent over horizontally. This enabled a reasonable length of wire to be
used without the need for very high masts. The direction of the electric field
in the radiated wave was no longer completely vertical but it had a strong
vertical component since the current standing wave was greater in amplitude
on the vertical portion.
A "T" aerial was another special type of vertical
aerial. This aerial consisted of a horizontal wire supported by two masts,
with a vertical wire suspended from its mid-point. It may be regarded as an
inverted "L" type aerial in which the horizontal portion is duplicated.
An enlarged picture of Detail A, the centre connection of a "T"aerial,
on the main diagram is above to
the left and and Detail C, the spreader details are shown on the right.
picture of Detail B shown on the main diagram is on the left above and
that of Detail D (down feed termination) is shown to the right.
vertical aerials were in common use throughout the RAF as they were simple
to construct and did not occupy a large amount of ground space. They were
used for both transmitting and for receiving. The most frequently used
aerial length was the 1/4 wave length aerial as it could be fed directly
using a co-axial cable. The aerials could range from 1/8 wave to 5/8 wave
length but these aerials needed an open wire feeder system and matching stubs.
Some aerials were completely vertical and others had the top turned in a
Above is a
diagram showing the various construction details of Vertical 1/4wave aerials.
elements were constructed using R6 aerial wire but often 100lb per mile copper
wire was used instead. R6 aerial wire was a three stranded, enameled copper
wire. When transmitting at over 5kw, type 286 insulators were used instead of
the pyrex glass type 50 insulators.
Several aerials could be erected using two masts, poles or even trees by
rigging them along a common static flexible steel wire rope triatic.
rigging details for attaching various 1/4wave vertical aerials are shown
of a 1/4wave vertical aerial to a co-axial cable.
box shown above is a Type 12 Junction Box which was used for connecting the
aerial to a 43ohm co-axial cable. A Type 2 or Type 7 Matching Unit was used if
connecting to a 75ohm co-axial cable. If it was not possible to bury the
co-axial cables they were carried overhead suspended from a triatic at
least 7ft 6ins above ground level. Eighteen 30ft long 14swg copper wires which
were soldered to the centre plate radiated outwards from the Type 4 Earth Mat
were usually buried about six to nine inches below the ground surface.
The vertical bi-conical aerial was a multi-wire
form of vertical aerial. It was only used in the RAF for receiving. The
multi-wire construction gave an increase in bandwidth, the frequency range was
in the order of 3 - 1. The aerial was constructed in three standard sizes using
100lb per mile copper wire for the six elements. All three aerial sizes were
terminated using a modified Type 12 Junction Box mounted on a standard Type 4
earthing mat. Aerial Type A was rigged from a special centre support column
mounted on top of a 90ft wooden lattice tower. Aerial Type B was rigged from a
special centre support mounted at the 60ft level of a 90ft wooden lattice
tower. Aerial Type C was rigged from a gibbet arm mounted on a standard 28ft
Air Ministry Works Department wooden pole.
Aerial Type A.
In the diagram above the aerial has an
effective length of 106ft and a frequency coverage of 2 to 6 Mc/s. The
construction and rigging details of the special support column (detail 1.)
and the aerial head cone (detail 2.) are shown to the right of the photograph.
Bi-Conical Aerial Type B.
On the right of the diagram above
the aerial rigged at the 60ft level of the 90ft wooden lattice tower has an
effective length of 67ft and a frequency coverage of 3 to 10 Mc/s. On the left
hand side of the diagram, the details of the layout of the six tensioning
pickets for all three types of bi-conical aerials is shown.
Rigging details of the Centre
Detail 4 - Fitting of the Aerial
Aerial Type C.
the diagram above the aerial rigged from the gibbet had an effective length of
23ft and a frequency coverage of 9 to 30 Mc/s. The aerial head cone is fitted in
the same manner as shown for the bi-conical aerial type B.
Detail 3 - The rigging of the
Aerial Base Cone of all three types of bi-conical aerials.
Detail 5 - The rigging and
fitting of the tension strops and pickets of all three types of bi-conical
Three-wire and Four-wire Rhombic Aerials.
A rhombic aerial consists, basically, of four conductors
joined to form a rhombus or diamond which concentrates the signal radiation in
a forward direction. The RAF found that the insertion of a resistance at one
end greatly improved the performance of the aerial for both transmitting and
receiving. This made the rhombic the best and most effective aerial used by
the RAF for long distance point to point signals traffic until the event of
The rhombic worked well for transmitting and receiving
over a wide range of frequencies and the use of multi-wire rhombics gave an even
greater bandwidth and thus better frequency ranges. The main disadvantage of the
rhombic aerial was the large area required for their installation.
diagram shows the layout of a typical rhombic aerial and associated masts.
The direction of the forward signal radiation in this diagram is from left
and Three-wire Rhombic aerials were used for transmitting up to 25KW and
for receiving. The Four-wire Rhombic aerials were only used for transmitting
at over 25KW. The aerial elements of all three types of rhombic were
constructed using 100lb per mile copper wire and were fed using the standard
RAF 600 Ohm open-wire feeder systems
The above diagram shows the rigging details of the major axis
ends of a typical rhombic aerial.
Until the end
of the 1950s all the various types of strops and halyards were made by hand
splicing the flexible steel wire rope. The introduction of the portable
"Talurit" press made the job of manufacturing the strops and halyards much
quicker and easier. The flexible steel wire rope was cut to size, the end fed
through the appropriate sized "Talurit" ferrule, the eye was formed and the
rope end fed back into the ferrule again. The ferrule was then placed into
the press between the swage blocks and squeezed by a few quick pumps on the
press lever and the job was done.
Rigging of the side axis of a
Rigging of the side axis of a
The side axis
of a Three-wire rhombic was rigged using the same type 47 spreader as seen
above but with a lug for the middle element positioned in the centre of the
spreader. An additional bracing strop was inserted between the end of the
halyard and the middle lug.
termination resistance details of Transmitting and Receiving Rhombic Aerials.
rhombic aerials were terminated using a non-conductive carbon resistance
inserted at the opposite major axis to the down feed from the aerial.
transmitting rhombic aerials were terminated using a 400ft long resistance
run built in the same manner as a 6inch spaced open wire feeder system at
the opposite major axis to the transmission feeder run. The resistance run was
constructed using 14 standard wire gauge nickel chrome resistance wire which
was short-circuited and earthed using a buried 2ft x 2ft copper plate.
Side view of a Terminated "V"
Plan view of a Terminated "V"
terminated sloping "V" aerial was a wide-band aerial which was normally only
used for receiving in the RAF. However it was used successfully for transmitting
on Ascension Island during the Falklands War in 1982.
It was superior to a dipole aerial for reception from
a given direction especially over long distances. From a practical point of
view its big advantage was that it only needed one supporting mast or tower
and in an emergency could even be rigged from a tall tree.
The rigging of
the halyard and the elements at the apex of the aerial are shown above in
Detail A. Detail B, on the right, shows the connection of the elements and
the 6 inch spaced downfeed.
methods of attaching the aerial element ends and the terminating resistors
to the earthing system using either wooden poles, concrete posts or steel
pickets are shown above. The value of the terminating resistors could be
changed to get the best possible working efficiency. The pairs of resistors
available ranged from 50 Ohms to a maximum of 390 Ohms but 360 Ohms was, in
general, the norm. The earthing system consisted of two 20 s.w.g. copper plates
buried upright at least 6ins below ground level and linked to each other by a
length of 100lb per mile copper wire.