|
|
|
|
|
|
In order for shrinking my luggage size, I
would like to bring wire antenna on this DXpedition. However I want to make QSO
as much as possible due to high possibility of this new entity. For the low
bands, a beam antenna even or a full-sized antenna would force my luggage fat.
I should study high band antenna deeply to begin with anyway.
Delta loop, vertical, or dipole would
become promising candidates for this DXpedition, because these antennas are
easy to be configured with copper wire. To make a proto type is one way to
study antenna but most effective solution to check the antenna is simulation.
As many of hams may know, EZNEC is well applied antenna simulation. EZNEC demo,
even some useful function was restricted, really works enough for these simple antennas.
I took the elevation angle and gain into
account as my priority. The band width is second priority for me. Comparing the
gain, the delta loop and the dipole are same, but the vertical gave approx -3dB
less than these two. Comparing the elevation angle, the delta loop gave 20deg,
but the dipole and the vertical gave 7degree higher than the delta loop.
7degree difference might impacts the traveling distance significantly. Flat
surface model shows 40% longer traveling distance in delta loop case. Regarding
the band width, these three are comparable each other for me. Finally I figured
out the delta loop gave suitable result according to my concept based on the
simulation. As the result of proto type test, I observed excellent capability
on antenna analyzer measurement.
Please see the data I referred this study
in below;
|
Calculated data EZNEC demo |
Measured data |
||
|
|
Azimuth Beam |
Elevation Beam |
SWR |
SWR [Measured] |
|
28Mhz Delta loop |
|
|
|
|
|
Gain= 8.67dBi |
Elevation Angle=20deg |
f0=28.15Mhz |
f0=28.4Mhz |Z|=46+0.8j SWR=1.15 |
|
|
28Mhz Vertical |
|
|
|
|
|
Gain=5.12dBi |
Elevation Angle=27deg |
f0=28.2Mhz |
|
|
|
28Mhz V-Dipole |
|
|
|
|
|
Gain=8.19dBi |
Elevation Angle=27deg |
f0=28.15Mhz |
|
|
Traveling distance/ Flat surface model
28Mhz delta loop dimension
Delta loop in test;
|
|
|
Dipole for 17M is well adjusted with no
problem at all.
|
|
|
Buddistick with extra grounding wires,
10ft 6pcs, shows good SWR quality.
|
3.5Mhz |
3.8Mhz |
|
|
|
|
10Mhz |
18Mhz |
|
|
|
