|Sommer XP50 Series Beam Antennas
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).
* 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%
P.O. Box 710
Geneva, FL 32732
Phone: (407) 349-9114 | Fax: (407) 349-2485