Directive Systems & Engineering DSEDBFEED User manual

DSEDBFEED Rev 10/20
Directive Systems & Engineering
2702 Rodgers Terrace
Haymarket, VA 20169-1628
www.directivesystems.com
703-754-3876
Dual Band W5LUA Type Dish Feed, Model DSEDBFEED
This feed design is based on the work of Al Ward, W5LUA, and represents an efficient way to
use one dish on two different ham bands. Unlike earlier multi band feed designs, W5LUA’s
design is capable of good performance on both microwave bands in use. In addition, the
higher isolation of this design, between 10 & 5.7 GHz simplifies installation requirements by
eliminating the need, in many cases, for a protective relay on the 5.7 GHz port. Isolation runs
over 30 dB and is typically 40 dB.
Note: All hardware is Stainless Steel unless otherwise noted.
BEFORE INSTALLING YOUR NEW ANTENNA, PLEASE BE SURE
TO READ THE ENCLOSED WARNING PAMPHLET.
INSTALLATION INSTRUCTIONS
1) Unpack antenna feed assembly and observe the location of the connectors and probe
orientation. For horizontal polarization, the probes must be oriented parallel with the horizon.
(The connectors will stick out laterally on the antenna.)

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DSEDBFEED Rev 10/20
2) Install the feed on your parabolic dish using the proper dimension of the focal point
(supplied with the dish) to the feed. Measure this distance from about 1/4 inch inside the open
mouth of the feed to the center surface of the dish. Our .6 m dish needs 11.25” from lip of the
feed to dish surface.
3) The dish feed SWR has been adjusted at the factory for maximum isolation between 10
GHz and 5.7 GHz. Do not try to adjust the 10 GHz or 5.7 GHz tuning slugs without proper
measuring equipment. All feeds are adjusted before shipment and are set for optimum
isolation. If you wish to adjust your feed for best VSWR, be aware that connecting cables can
introduce serious mismatch errors at these frequencies. The 3/4” tube tuning adjustment
affects 10 GHz primarily. The screw on the large diameter portion is for 5.7 GHz, but can
affect 10 GHz at certain positions. Use caution when tuning! Do not move this slug very far, or
serious degradation at 10 GHz will result.
DUAL BAND W5LUA FEED FOR 5.76 & 10.368 GHz Amateur bands. Each plot displays the
VSWR (return loss) and isolation between ports for the respective band. The feeds are
optimized for 10 to 5.7 GHz isolation when shipped from the factory. Considerable effort has
been made to produce best isolation between the ports, while maintaining high return loss. It’s
all a trade-off!
10 GHz isolation is quite critical and can be affected by what the feed “sees”. It is always a
good idea to check port to port isolation whenever you adjust the feed location on your
parabolic reflector.
Normally, the dish will have little effect on port isolation when properly installed, but unwanted
reflections back into the feed can degrade the >30 dB isolation value. These plots were made
with the feed only in free space. Actual results should be the same unless there is blockage at
the mouth of the feed.

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DSEDBFEED Rev 10/20
5760 MHz isolation is very high and is not influenced by much, since the 10 GHz waveguide
portion of the dual band feed is too small, and cannot support 5.7 GHz propagation. 70 dB is
typical.
The 5760 MHz VSWR is about -18 to20 dB or more when the 10 Ghz isolation is at optimum.
Directive Systems Warranty Policy
All Directive Systems antennas are built with the finest materials available. We take great pride in
building a quality product that will give years of good service and performance. If there is a defect in materials
or workmanship within 90 days of purchase, Directive Systems will repair or replace the defective part, free of
charge, to the original purchaser. DO NOT RETURN ANYTHING WITHOUT PRIOR AUTHORIZATION
FROM DIRECTIVE SYSTEMS. Please contact us either by phone or email describing the problem and we
will work to resolve it.
If, after examining a new antenna you received, you are not satisfied, contact us immediately for return
authorization and refund. ANY ANTENNA THAT HAS BEEN MODIFIED WILL BE SUBJECT TO A
RESTOCKING CHARGE. IF AN ANTENNA IS SO MODIFIED AS TO MAKE IT UNUSABLE, DIRECTIVE
SYSTEMS RESERVES THE RIGHT TO REFUSE TO ACCEPT THE ANTENNA FOR RETURN.