DB228- BROAD BAND ANTENNA, 9 or 12 dB GAIN, 138-174 MHz



A high gain, broad band antenna for 138-174 MHz, the 8-dipole DB228 combines two DB224E offset-pattern antennas to provide a 9 dB gain omni or a 12 dB gain offset horizontal pattern. Both DB224E antennas are mounted with the ends together, and the phasing harness is terminated at the center. A special bracket positions the antenna at a predetermined distance from the tower.
Flexible Mounting - Normal mounting is half above and half below the top of the tower; however, the DB228 can be fully side mounted.
Broad Bandwidth - Can provide symmetrical patterns for both transmit and receive, and can be used in single or multi-frequency systems.
Offset or Circular Patterns - When all elements point toward the tower, a circular pattern is created; when all elements point away from the tower, an offset pattern occurs. The pattern can be changed in the field by rotating the mast 180 degrees.
Lightning Resistant - The radiators operate at DC ground, and the aluminum mast with its pointed cap provides a low resistant discharge path to the tower or ground system.
Ordering Information - Order DB228 for omni and DB228E for offset pattern. Use the correct letter for frequency, and specify termination if non-standard. Included are NSO18279-001 mounting bracket, one sway brace and adjustable clamps for 12" to 36" (304.8 to 914.4 mm) between tower legs. 12038 Sway Brace, needed when the entire antenna is side mounted, and Dipole Stabilizer Kit 12088 (8 required) are optional. Order jumper cable separately, if desired





Mechanical data

Radiating elements (aluminum) - in. (mm) .5 (12.7) ODwith .058 (1.47) wall

Maximum exposed area
(flat plate equivalent - ft.sq (m.sq) 7.3 (..68)
Lateral thrust at 100 mph (km/hr) - lbf (N) 292 (1,298.8)

Wind rating:
Survival without ice - mph (km/hr) 100 (161)
Survival with .5" (12.7 mm) radial ice - mph (km/hr) 74 (119

Overall length (150-175 MHz) - in. (mm) 488 (12,395)
Shipping length - in. (mm) 148 (3,759)

Net weight (w/clamps, brackets) - lbs. (kg) 72 (32.66)
Shipping weight (w/clamps, brackets) - lbs (kg) 142 (64.41)

Note: The mechanical specifications are degraded for the antenna covering the 120-150MHz band.


Electrical Data

Frequency Ranges* - MHz A = 150-160, B = 155-165,C = 164-174, E = 138-150

Bandwidth (150-174 MHz) - MHz 10
VSWR 1.5 to1 or less
Nominal impedance - ohms 50

Gain (over half-wave dipole) 9 Omni pattern - dB, 12 Offset pattern - dB

Maximum power input: 500 watts
Vertical beamwidth (half power points) 8

Lightning protection: Direct ground

Standard Termination: Captive Type N-Male attached to end of a flexible lead.
Other fittings are available on special order. If UHF connector is required, and adapter is provided.

*Note: Special frequencies are available.