10 GHz antenna gain measurements
On the 29 th of April 2000 some 10 GHz antennas were measured. The purpose
of this exercise was to find out if the expected gain could be realized.
Measurements were carried out on a professional antenna test range.
(guess where)
We had three dishes for measuring.
-
PA0WSO, a 70 cm dish with a so called chaparral style feed
-
PE1AEO, a 55 cm dish with a so called chaparral feed
-
PE1CQQ, a 45 cm dish with a dipole feed.
First a measurement was done with a standard gain horn. These results were
used for determine a correction factor. This correction factor is used
for calculating the gain of the antenna under test. After that the three
antenna's were measured.
On the receiver side two measurements are simultaneous done. The first
one is the power received by the test antenna. The second one is the power
received by a reference antenna which is pointed to the transmit antenna
and not moved during the whole measuring session. Any drift in the transmitter/receiver
or change in path loss are canceled out in this way.
The following figures give an impression of the measured diagrams. Measurements
are done in 3D i.e. horizontal and elevation. This type of measurement
gives a lot of data but takes a lot of time. Due to limited time we only
measured an horizontal range of +/- 20 degrees.
The figures show only the horizontal plot at the maximum gain. There
are 3D plots available upon request.
Click on the figures for a better view.
 |
 |
|
Diagram PA0WSO dish mounted normal.
|
Diagram PA0WSO dish mounted upside down.
|
 |
 |
|
Diagram PE1AEO dish.
|
Diagram PE1CQQ dish.
|
|
Owner
|
Diameter
|
f/D
|
Theoretical gain @ 50% eff
|
Measured gain
|
Efficiency
|
| PA0WSO |
0.75
|
0.45 |
34.9
|
34.7
|
47.7
|
| PE1AEO |
0.61
|
0.35 |
33.1
|
31.6
|
35.4
|
| PE1CQQ |
0.45
|
0.28 |
30.5
|
27.6
|
25.6
|
Diameter in meters.
Gain in dBi.
Efficiency in %.
Conclusions:
-
Claimed efficiency of more than 50% in the radio amateur world are hard
to believe.
-
A very stable mounting of the feed is a must.
-
The so called chaparral feed was designed for an F/D of 0.4.
-
The dipole feed as published in the RSGB VHF manual and many other magazines
is an easy solution. Do not expect miracles. The 3D plots are showing some
very bad behavior. Some people use this feed also on 24 GHz. Results might
be even worse. An alternative for this type of feed might be an corner
reflector sold by PROCOM. Although also some bad behavior in the 3D diagram
has to expected.
Future 10 GHz measurements on new dishes are planned. Also on 24 GHz we
planned some tests.
Results of new measurements.
Back to PE1CQQ 
Page.
(c) PE1CQQ Last update 16-3-2001