Sommer XP50 Series Beam Antennas
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Series XP50 -4.4 m / ~15-ft Boom

Active Elements

20 m
3x driven full size (1/2 wavelength) elements
LOG-1 + LOG-2 + LOG-3
15/17 m
3x extended 1/2 wavelength plus elements about 5/8 wavelength long
LOG-1 + LOG-2 + LOG-3 + EL-1B on 15 m + EL-1C on 17 m
10/12 m
6 x 1/2 wavelength collinear elements 2 x 3 side by side
LOG-1 + LOG-2 + LOG-3 + EL-1A + EL-2A + EL-3A + EL-1B as 3/8 radiator
30/40 m
All driven elements
LOG-1 + LOG-2 + LOG-3 + EL-1B + EL-1C + EL-3A as "C"
NOTE: Well-built multiband beams with driven elements have a 1-2 dB higher gain than conventional systems with the same boom length and bandwidth (better element illumination).

The XP50, with a boom length of only 4.4 m / 15 ft, represents our most popular beam. Considering the cost-ratio for mast/rotor/beam in relation to its DX efficiency, the XP50 series is equivalent to a 4-element monobander. Under test conditions, the XP50 Series performs as well as 4-element monobander with an advertised 10 dB gain.

The model XP504 antenna is shown in Figure A. In this configuration the 20 m band is using three actively driven full-size elements and offers a solid 6 dB/D forward gain.

For the 15 m (and 17m) band, three directly fed 5/8-wave elements form a typical band gain of 7 dB/D in conjunction with element 1B. Operation on 17 m requires an optional 8.2 m (26 ft) element at boom location Z which does not influence the 10-20 m settings, but has the same properties on 15 m.

All elements are working on 10 and 12 meters and contribute to a 6-7 dB/D gain. A coaxial stub housed in a plastic box enables operation on the 30 m band without any mechanical extensions. The typical gain with this configuration is about 0 dB/D.

The 40 m band is activated by use of an individual power coil mounted at Y, which yields a 0 to 2 dB/D gain on this band.

Remember, a 3-element monoband beam has 4 to 6 dB/D (see ARRL Antenna Book).


Notes:
* Gain determined in the main lobe as described in the ARRL Antenna Book, 14th ed. pg. 15-23. Measurement accuracy according to CCIR plus/minus 2dB.
** F/B ratio and SWR vary according to conditions--e.g., electrical height above ground.
*** Plus or minus10%

Sommer Antennas

P.O. Box 710
Geneva, FL 32732
Phone: (407) 349-9114 | Fax: (407) 349-2485