Updated October 31,
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New for December
2010! The original work on antenna horns was done by William
T. Slayton. His work is was documented in an NRL report in 1954:
NRL Report 4433, DESIGN AND
CALIBRATION OF MICROWAVE ANTENNA GAIN STANDARDS. This resource
gives dimensions for construction of a series of microwave horns
of known gain, and may be used as a calibration reference. The horns
are designed to match up well to standard waveguide sizes. Virtually
all standard gain horns on the market follow the dimensions called
out in this report. Slayton never made an extra dime from his work,
but the microwave industry showed an immediate profit that continues
to this day. He is in the Microwave
Hall of Fame!
New for April
2011! We have been in contact with William Slayton's daughter
Charlotte and she provided us with some excellent materials! Starting
with this picture of him:
William T. Slayton,
Radio Technician First Class
Now we have an improved
copy of the NRL report, plus an article Slayton wrote for Electronics
Magazine in 1955, and a copy of a speech he gave in 1980, three
years after his retirement. It is all in our download
area for your review! Here is a biography of Slayton:
William (Bill) Taft Slayton,
Jr. was born on February 1, 1914, in Morrisville, VT, the son
of a doctor and grandson of a Civil War captain. Mr. Slayton studied
electrical engineering at the University of Florida in Gainesville,
FL, and at the George Washington University in Washington, D.C.
During World War II, Mr. Slayton served as a Radio Technician
First Class in the United States Navy, receiving training at the
U.S. Naval Training School, Theodore Herzl, Chicago, IL; College
of the Ozarks, Clarksville, AR; and the Naval Research Laboratory
(NRL) in Washington, D.C. After the War, Mr. Slayton continued
his Navy service as a civilian employee at the NRL, during which
time he invented a design for microwave gain-standard horns that
is still used today. Following a brief employment with The Martin
Company in Baltimore, MD, Mr. Slayton returned to the service
of the U.S. Navy as a civilian employee at the Westinghouse Air
Arm, in Baltimore, MD. In 1961, Mr. Slayton, along with many fellow
engineers from the NRL, moved to the National Aeronautics and
Space Administration, Goddard Space Flight Center, in Greenbelt,
MD. Mr. Slayton continued his service as a senior engineer in
the unmanned space flight program at NASA until his retirement
in 1977. After enjoying many years of retirement in Florida and
North Carolina, Mr. Slayton died on December 1, 2000.
antenna Rule of Thumb
antenna pattern for a horn antenna can be approximated as:
How do you determine
the polarization in the example below?
This information came from Carlos,
My name is Carlos, I'm a
Spanish EE specialized on RF. I work at the R&D department
of a broadband microwave links manufacturer company. I write you
about the question on "how to determine what polarization
a dielectric plate loaded feed horn is".
As you may know, the dielectric
plate is made to produce a 45º phase shift in the two axes,
so TE11 wave is split into two linearly polarized TE11 waves with
90º phase shift due to the dielectric constant and plate
shape/size, it then becomes a circularly polarized wave. Of course
this dielectric should present low loss at working frequency,
so it's usually made of PTFE.
What is the circular direction
of a dielectric loaded feed horn? The easy answer is: the opposite
direction in which the TE11 wave finds the plate at 45º.
In the example, that feed radiates in RHCP, if the TE11 wave comes
from the back side.
Other ways to convert linear
to circular in waveguides are squeezed pipes or screw polarizers.
There is little information about polarizers on the net, apart
from some patents, sat TV shops selling plates without providing
much info, or some amateur radio guys like:
Here's another example
of feeding RHCP.