Procom PMC 1250 - Manual

PMC 1250
Phasing-Clamp for Creating a Certain Radiation Pattern
using Two Antennas
DESCRIPTION
The PMC 1250 can be used to create a certain desired radiation pattern
in the horizontal plane using two vertically polarised antennas mounted
side-by-side in a certain, prescribed distance, and feeding them both in
the correct amplitude and phase relationship. The PMC 1250 is mainly
designed for the 144 - 175 MHz band.
The PMC 1250 is equipped with two vertical 38 mm mast tube mounting
studs for the two antennas. One of the tubes is welded permanently to
one end of the supporting boom, and the other is able to slide along the
boom where it can be fastened at an arbitrary distance. The position of
the main clamp for the supporting mast can also be adjusted, and it
should always be positioned halfway between the two antennas.
Mostly, the antennas are fed with currents of the same amplitude, and
only the phase relationship and the distance between the antennas are
varied to produce the desired coverage. The phase relationship is
changed by introducing a delay line in one branch of the feeding cable
system.
The figure below shows representative horizontal patterns for various
values of distance D and phase delay Pd. Obviously, given a particular
antenna site and a certain geographical area to be covered, a system
like this offers a large degree of design-freedom to choose the best
characteristic possible.
Please note that the PMC 1250 should always be mounted at the top of
the supporting mast. If the PMC 1250 is sidemounted, the radiation
pattern will be very difficult to predict.
Procom offers the service of designing and quoting systems like this
especially according to the requirements of our customers.
SURVEY OF RADIATION PATTERNS (Relative field strength)
ORDERING DESIGNATIONS
TYPE PRODUCT NO.
PMC 1250 100000039
SPECIFICATIONS
FUNCTION PHASING-CLAMP FOR CREATING
A DESIRED COVERAGE
FREQUENCY 66 - 88 MHz: 1/16 λ < D < 1/4 λ
144 - 175 MHz: 1/8 λ < D < 1/2 λ
DISTANCE
BETWEEN ANTENNAS
(Variation range)
0.23 - 1.20 m
DIAMETER OF
MOUNTING STUDS
Ø 38 mm
WIND SURFACE 0.10 m²
WIND LOAD 127 N @ 160 km/h
MATERIALS Boom: Hot dipped galvanized steel
Fittings: Stainless steel
TOTAL HEIGHT Approx. 1.28 m
WEIGHT Approx. 8.0 kg
MOUNTING On 38 - 65 mm outer diameter mast tube
Antennas should be mounted symmetrically in relation to the mast.
PROCOM A/S reserve the right to amend specifications
without prior notice.
06/12/11