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- 7501450 -
7501 450
Plan Vertical
Jaybeam Limited
Rutherford Drive, Park Farm South Wellingborough,
Northamptonshire, NN8 6AX, England
Tel: +44(0)1933 408408 Fax: +44(0)1933 408404
WWW.jaybeam.co.uk
DIPÔLES VHF & UHF ALIMENTÉS À LA BASE
Toutes les bandes de fréquences PMR se retrouvent ici, ainsi que les bandes
aviation VHF et UHF (types 7500 et 7502).
Type
Fréquences disponibles (MHz)
ROS
Gain (dBd)
Impédance (Ohms)
Polarisation
Rayonnement plan vertical
(-3 dB)
Puissance Maximum (Watts)
Sortie
Fixation
Longueur (cm)
Poids (kg)
Charge au vent @ 45 m/s (N)
reserve the right to modify or amend any antenna or specification without prior notice
Tel: +33 2 47 30 69 70, Fax: +33 2 47 57 35 06
7501 450
420 - 470
<1.5 : 1 Typique
<1.8 : 1 Max.
0
50
Verticale
80°
100
N femelle
Brides de fixation
intégrée
58
0.95
16
MAT Equipement
ZI La Boitardière, Chemin du Roy
37400 Amboise
WWW.matequipement.com
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Summary of Contents for MAT Jaybeam 7501 450
- Page 1 Charge au vent @ 45 m/s (N) reserve the right to modify or amend any antenna or specification without prior notice Jaybeam Limited MAT Equipement Rutherford Drive, Park Farm South Wellingborough, ZI La Boitardière, Chemin du Roy Northamptonshire, NN8 6AX, England...
- Page 2 Surface au vent (m2) 0.05 reserve the right to modify or amend any antenna or specification without prior notice Jaybeam Limited MAT Equipement Rutherford Drive, Park Farm South Wellingborough, ZI La Boitardière, Chemin du Roy Northamptonshire, NN8 6AX, England 37400 Amboise...
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Page 3: Antenna Siting
VHF AND UHF ANTENNA INSTALLATION INSTRUCTION PREFACE Introduction Scope of the installation instruction GENERAL ASPECTS OF PAGING COVERAGE General Receiver types, sensitivity Data to be considered Field coverage test Coverage of areas with poor reception Mufti- transmitter system Theoretical approach ANTENNA TYPES AND THEIR CHARACTERISTICS Groundplane antenna Dipole antenna... - Page 4 1. PREFACE 1.1 Introduction The VHF and UHF paging systems require an antenna to transmit the paging signals from the central equipment to the signal receivers or transceivers. The paging system can use 5 Watt transmitters or low power (2 Watt VHF or 1 Watt UHF) transmetters mounted on or near a master operator console.
- Page 5 2.4 Field coverage tests The first step is to identify the special problems of the site by carrying out a field intensity test there. This will locate any "weak" or "dead" areas and by trying different antenna locations the most suitable position will be found. If a single transmitter will not give sufficient coverage of the whole site, there are several methods of improving the situation.
- Page 6 3. ANTENNA TYPES AND THEIR CHARACTERISTICS 3.1 Ground plane antenna The most commonly used antenna for VHF systems is the ground plane antenna. Characteristics: - Can easily be installed on a metal mast. -Gain is 0 dB, omnidirectionnal. - Its beam has a slight elevation of 10°.
- Page 7 4. ANTENNA SITING 4.1 General This chapter describes antenna siting for a ground plane antenna but applies also for other antenna types, of course. 4.2 Ground plane antenna The externat antenna usually applied in the paging system is a vertical dipole with ground plane rods. The most effective radiation direction for this type of antenna is in the horizontal plane, whilst the signal strength vertically above and below the antenna is comparatively weak, especially in the area below the ground plane rods.
- Page 8 4.4 Reflection When electromagnetic radiation strikes a surface, part of the radiation is allowed to pass or is absorbed, and part is reflected. The pattern and degree of reflection depends on the nature and size of the reflecting surface and the angle at which the radiation The reflected radiation can interfere with the direct radiation.
- Page 9 Should the building comprise a high and low section, very good resuits can be obtained by situating the antenna on the low section. The antenna then beams the signal horizontally - the most effective way through the high section, the radiation requiring to pass through only a limited number of thin walls instead of a large number of fixed concrete floors.
- Page 10 Where an outdoor area must be served, the antenna is best mounted at a height of 10 - 20 metres (30 - 60 ft) in the centre of the area. If high buildings or steel structures are found in the area, however, reception in buildings in the "shadow" of these obstacles may be inferior.
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Page 11: Coaxial Cable
Leaky coax cables are available with different radiation levels (different number or wider slots) which can be used for different applications; - cables with minimum radiation and low attenuation for long lengths, to be used in relative narrow but long areas such as tunnels, subways, mines etc. - cables with higher radiation and higher attenuation so shorter lengths, to be used in tall buildings.