|Sommer XP80 Series Beam Antennas
With a boom size of 8 m / 26 ft, the XP80 is a real surprise, even for experienced DXers! Not only in the transmitting mode, but also when receiving rare DX signals near the band ends. In critical pile-up situations, the XP80 yields an outstanding and unexpected signal reading and shows well its enormous directivity and the capability to fade-out heavy QRM interfering from the side and back.
The model XP804 antenna is shown in Figure A. In this configuration the 20m band is using five actively driven full-size elements and turns out a solid 10 dB/D forward gain.
For the 15 m (and 17 m) band, five directly fed 5/8-wave elements, in conjunction with elements 1B and 5A, provide a typical 10.5 dB/D forward gain. Operation on 17 meters 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 10-11 dB/D gain.
A coaxial T-match system on Log. 5 enables operation on the 30 m band without any mechanical extensions. The typical gain with this configuration is about 0 dB/D.
The 40m band is activated by use of an individual power coil at Y, yielding a 0 to 3 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%
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