Transcript
Installation PH and PHE Series Phasing Harnesses MOUNTING The SMD range of side mounted dipole antennas offer system designers a wide choice in the areas of horizontal radiation patterns and gain. The following radiation patterns were measured when an SMD1 was mounted with the stated antenna to mast spacings. The pattern changes dramatically with this spacing on other than a 50mm diameter mast. In the case of a larger mast (eg: lattice mast structure), the overall effect is thinner main lobes and more pronounced nulls. PHASING When phasing SMD antennas, designers should first take into account the antenna to mast spacings. The effect in the H plane of phasing SMD antennas is fairly minimal, with only a slight reduction in the horizontal beamwidths (as shown for a single antenna) when up to four antennas are phased. Gain is increased nominally by 3dB when a second antenna is used and 6db for an array of four. Vertical radiation patterns are generally larger than for a series fed colinear (ie fibreglass enclosed) due to the directional nature of the array - one of the obvious advantages of using an SMD antenna. SMD antennas also offer beamtilt stability over a fairly broad bandwidth (up to +/- 10%) and direct grounding for lightning protection. The chart below indicates the optimum spacings between antennas when phasing. Our range of PH and PHE phasing harnesses is listed on pages 152 & 153 of this catalogue.
0°
0°
1.0
330°
0° 30°
.9 .8
300°
.9
.7
.8
.6
.7
60°
.5
1.0
1.0
330°
330°
.7 .6
300°
.4
.4
.2
.3
.3
.1
.2
.2
270°
90°
.1
.1
90°
120°
240° 240°
120°
120°
150°
210°
90°
270°
270°
240°
60°
.5
60°
.5
.3
30°
.8
.6
300°
.4
.9
30°
150°
210° 150°
210°
180°
180° 180°
Model No.
MHz Centre D= 1/4 wave D= 1/2 wave D= 3/4 wave D= 1 Wave Frequency 77
974
SMD2
161
SMD4
460
SMD1
Doc Ref: INS-37706-1
3/4 λ Spacing
1/2 l λ Spacing
1/4 λ Spacing
1 λ Spacing
S
1948
2922
3896
2922
466
932
1398
1863
1390
163
326
489
652
489
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Installation Phasing UHF Dipole Antennas When using side mounted dipole antennas it is important to ensure that the antenna to mast spacings AND the antenna to antenna spacings are optimised for your applications. The following graphs indicate the optimum antenna centre to antenna centre spacings and antenna to mast spacings for your frequency of use.
Four Stack
On the previous page is an illustration of the various patterns effected at VHF frequencies when side mounted dipole antennas are mounted at differing distances from the support mast. A similar series of patterns will also be effected at UHF frequencies, however it is important to note that for any given support mast, the effect on a UHF antenna will be greatly exaggerated, with deeper nulls and more pronounced peaks in the pattern. We urge the use of our BA, EA and OA Series arrays at UHF for predictable pattern performance. Please note that when using two side mounted dipole antennas phased together, total antenna gain will be increased by 3 dB and if using four antennas, the antenna gain will be increased by 6 dB. This increase in gain is IN ADDITION to any gain which is afforded by the manipulation of the antenna pattern through antenna to mast spacings as shown opposite.
Two Stack
PLEASE NOTE: We strongly recommend against the phasing of 800 MHz side mounted dipole antennas as the control of the dimensions is far too critical to be adequately controlled in the field. Thus, we do not publish any information to assist in the phasing of our 800 MHz side mount dipole antennas. Dipole Spacing vs Frequency Centres - Mast to Dipole - Dim S
Meters
Meters
Dipole Spacing vs Frequency Centres - Mast to Dipole - Dim D
MHz ________ 1/4 Wavelength ------------- 1/2 Wavelength
MHz SMD4
2 of 4 Doc Ref: INS-37706-1
©2003 R F Industries Pty Ltd
Installation Phasing VHF Dipole Antennas When using side mounted dipole antennas it is important to ensure that the antenna to mast spacings AND the antenna to antenna spacings are optimised for your applications. The following graphs indicate the optimum vertical spacings and antenna to mast spacings for your frequency of use. Earlier in this section is an illustration of the various patterns effected at VHF frequencies when side mounted dipole antennas are mounted at differing distances from the support mast.
increased by 3 dB and if using four antennas, the antenna gain will be increased by 6dB. This increase in gains is IN ADDITION to any gain which is afforded by the manipulation of the antenna pattern through antenna to mast spacings as shown opposite. PLEASE NOTE: For both SMD1 and SMD2 antennas, the full band coverage of the antennas can be maintained for a stack of two or four antennas if the correct phasing harness is used.
Please note that when using two side mounted dipole antennas phased together, total antenna gain will be Two and Four Stack Dipoles Dimension - S
Meters
Meters
Two and Four Stack Dipoles Dimension - D
MHz SMD1 MHz 1/2 Wavelength
Meters
Meters
1/4 Wavelength
MHz MHz 1/4 Wavelength
1/2 Wavelength
SMD2
3 of 4 Doc Ref: INS-37706-1
©2003 R F Industries Pty Ltd
Installation Phasing Yagi Antennas The phasing of yagi antennas can be done in vertical or horizontal polarisation and will, when properly implemented, boost the available gain by 3.0 dB (for two antennas) or 6.0 dB (for four antennas) over the gain for a single antenna. The phasing of yagi antennas requires critical control of both the "Baying" and "Stacking" dimensions as shown in the illustrations. It is important to note that in all cases, these dimensions (B and S from our illustrations) should be identical at any one frequency. These distances vary with the number of antenna elements and the frequency of operation. To ensure
that your antennas are phased at the optimum distance, use the following charts to determine the distance which should be used for the antennas you are using. PLEASE NOTE: If you are phasing antennas in MULTIPLE directions, rather than phasing yagi antennas together for additional gain in a single direction, you will experience a net LOSS in gain over your individual antenna gain of 3.0 dB for a two way split and 6.0 dB for a four way split. For more information on the effect of phasing yagi antennas, please contact your nearest RFI office.
Stacking Dimensions
Baying Dimensions Vertical Polarisation
Vertical Polarisation
Horizontal Polarisation
Horizontal Polarisation
UHF
VHF
Yagi Frequency vs Spacing
Yagi Frequency vs Spacing 16 Element ___ 9 Element ---- 6 Element
Recommended Dimension 'S or 'B' Meters
Meters
Recommended Dimension 'S or 'B'
Doc Ref: INS-37706-1
Recommended Dimension 'S or 'B'
15 Element ------ 6 Element Meters
Meters
Recommended Dimension 'S or 'B'
6 Element ---- 3 Element
6 Element -----3 Element
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