Shively Labs FM Antennas and Accessories
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Typical Data for
Model 6813 FM Antenna (half-wave-spaced)

True Circular Polarization

Power Rating: 3 kW per Bay

Shively Standard Features:

  • Ring Stub Design
  • Consistently Predictable Patterns
  • Low Weight and Windload
  • Digital Ready
  • Pattern Studies Available
  • No Factory Personnel Needed to Install
  • Adjustable Fine-Matching Transformer
  • Radomes and Deicers Available
  • Rugged Corrosion-Resistant Mounts
  • Works with Regular Towers; No Need for Special Frequency-Sensitive Tower Sections
  • Pressure Relief Valve for Easy Purging of the System
  • Special Spacing, H/V Ratios, Null Fill and Beam Tilt Available

Performance Specifications:

Polarization:
Right circular.
VSWR:
1.06 : 1 ± 100 kHz.
1.14 : 1 ± 200 kHz
Azimuth Pattern Circularity:
Horizontal component ±1.5 dB on pole.
Input Connection:
1-5/8 in EIA Female.

Electrical Specifications (half-wave-spaced):
No. of
Bays		 Gain
 Power
Rating
kW		 No. of
Bays		 Gain
 Power
Rating
kW
Power dB Power dB
1
 Not available
7
2.22
3.47
12
2
0.70
-1.54
6
8
2.53
4.03
15
3
1.01
1.05
9
10
3.14
4.96
15
4
1.31
1.17
10
12
3.75
5.74
15
5
1.62
2.08
12
14
4.35
6.39
15
6
1.92
2.83
12
16
4.96
6.96
15

Notes:

Our gain figures are derived from the computed directivity and include the losses in the antenna feed system. Gain is computed for 98 MHz and will vary across the band.

Gain is provided for one polarization and is equal in circularly polarized antennas for both horizontal and vertical components. Gain will be reduced if null fill, beam tilt, special H/V ratio, or special wavelength spacing is provided. Gain will increase in a directional array by the directivity of the azimuth pattern.

Size and Weight (half-wave-spaced):
No. of Bays Vertical Tower Space
 Weight
Antenna radiation aperture
 Physical
space used
 Total tower space recommended
 without
radomes
 with
radomes
 with radomes &
1/2"radial ice
ft m ft m ft m lb N lb N lb N
2
5
1.6
14
4.6
25
8.2
96
428
166
740
362
1615
3
10
3.3
19
6.2
30
9.8
138
615
243
1084
547
2440
4
15
4.9
24
7.9
35
11.5
181
807
321
1432
731
3260
5
20
6.6
29
9.5
40
13.1
250
1115
398
1775
916
4085
6
25
8.2
34
11.2
45
14.8
266
1186
476
2123
1101
4910
7
30
9.8
39
12.8
50
16.4
308
1374
553
2466
1285
5731
8
35
11.5
38
12.5
55
18.0
329
1467
609
2716
1426
6360
10
45
14.8
48
15.7
65
21.3
404
1802
754
3363
1778
7930
12
55
18.0
58
19.0
75
24.6
489
2181
909
4054
2147
9576
14
65
21.3
68
22.3
85
27.9
574
2560
1064
4745
2516
11221
16
75
24.6
78
25.6
95
31.2
589
2627
1220
5441
2886
12872

Windload (half-wave-spaced):
No. of
Bays		 Revision "C"
 Revision "F"
without radomes
 with radomes
 with radomes & 1/2" radial ice
 without radomes
 with radomes
 with radomes & 1/2" radial ice
lb N lb N lb N ft² m² ft² m² ft² m²
2
123
549
331
1476
399
1780
4.4
0.4
9.4
0.9
11.5
1.1
3
199
888
511
2279
619
2761
7.0
0.7
14.6
1.4
17.9
1.7
4
275
1227
690
3077
838
3737
9.7
0.9
19.7
1.8
24.4
2.3
5
351
1565
870
3880
1058
4719
12.4
1.2
24.9
2.3
30.9
2.9
6
427
1904
1050
4683
1278
5700
15.1
1.4
30.1
2.8
37.4
3.5
7
503
2243
1229
5481
1497
6677
17.7
1.6
35.3
3.3
43.9
4.1
8
552
2462
1382
6164
1670
7448
19.5
1.8
39.5
3.7
48.9
4.5
10
674
3006
1713
7640
2067
9219
24.1
2.2
49.1
4.6
60.7
5.6
12
826
3684
2072
9241
2507
11181
29.5
2.7
59.5
5.5
73.7
6.8
14
978
4362
2432
10847
2946
13139
34.8
3.2
69.8
6.5
86.7
8.1
16
1130
5040
2791
12448
3386
15102
40.1
3.7
80.2
7.5
99.6
9.3

Notes:

  1. The mounting structure must not flex more than ± 1/2 in (1.2 cm) in any ten-foot (3-meter) section. Five feet (1.5 m) of mounting structure is required above and below the antenna bays for proper pattern formation.
  2. Antenna radiation aperture is the distance from the center of the top bay to the center of the bottom bay. Physical space used is from the top of the top bay to the input flange at the bottom of the array, or the bottom of the bottom bay in a center-fed array. Total tower space recommended allows ten feet (3 m) of clear tower space above and below the antenna to protect from pattern interference by other antennas. At frequencies lower than 98 MHz, each of these dimensions will increase by up to 1 ft (0.3 m) per bay.
  3. Seven bays or less are normally end-fed. All antennas supplied with beam tilt will be center-fed. Antennas with an odd number of bays are normally not available with center feed.
  4. Windload and weight tabulations are estimates and assume 98 MHz. They include the bay, interbay feedline, input connection, and a fine-matching transformer. No values have been included in these tabulations for mounts. Actual values vary with the specific installation. Contact us with details of your installation if more precise values are needed.
  5. Antenna windloads are calculated for 112 mph (180 kph), using 50 psf (2400 N/m²) for flats and 33 psf (1600 N/m²) for rounds] per EIA standard RS-222-C and CSA standard S37-94. The surface area is calculated per EIA standard RS-222-F (CaAc).
  6. Deicers add approximately 1 lb (4.4 N) per bay in weight and 2 lb (8.9 N) or 0.05 ft² (0.005 m²) per bay in windload.
  7. Ask for technical assistance at Shively if you are planning to mount antennas on AM towers or install them at altitudes over 3,000 ft (915 m) above mean sea level.
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Last updated: 10/09/2007
Webmaster: Al Friend
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