You may notice that I sometimes repeatedly ask for callsign or
report and this is for me to assess reception difference between RX
antennas and TX antenna.
Measuring Ground conductivity at 3V8SF
In order to better assess antenna performance, ground
conductivity measurement had to be conducted. To do so,
two 1m steel probes were pushed in parallel into soil.
An antenna analyzer measured the complex impedance which
was found to be 56.5+j17. I have used DL1GLH's
calculation on his website to convert that to
conductivity which is found to be 21.7 mS/m. Of course
this is not very representative of all the soil around
the antenna neither the entire earth depth but should
give some indication.
Radiation patters: Blue for
City QTH, Red for current 3V8SF QTH
I here above compare antenna radiation pattern of my TX
antenna between city location and current 3V8SF
location. The take-off angle goes from 35 down to 19.9
160m Top-loaded Vertical in 3V8SF
Preparing for the new season, I designed and built a
top loaded vertical antenna for 160m in 3V8SF
location. The antenna is 17m high with two top loading
wires 12m each. For instance, the antenna has 8 radials,
19m each. A shunt match coil is added at feedpoint.
First testing night QSOs - 21/09/2018
First measurements showed that the wire interacts with the metallic hanging mast
so I had to put it 1.5m away then adjust the hairpin match again.
The map above shows the stations I could QSO during the night of September 21st.
The antenna performed really well with 100W only. Unfortunately, the beverage
antenna was disconnected.
3V8SF as RXed by VY2ZM 00:43z
3V8SF QSO with FR4NT 01:32z
260m Beverage Antenna beaming North
I installed this beverage for experimental purposes. It
was used in Spring Stew Perry DX Challenge to check the
performance listening to NA station (antenna beaming).
The location is approximately 100km away from 3V8SS
where the TX Inv-V antenna is.
26 Ground spikes were prepared in advance. 1m long PVC
pipes were hooked up on the spikes partially buried. Due
to some constraints, the beverage length was limited to
240m beaming North America (at 291 deg). One ground rod
(1m long) is installed at each antenna end. The receiver
end has 2 radials (15m).
The antenna was connected to Reverse Beacon Network
(3V/KF5EYY). After 5 days of receiving, data was
gathered for 160m. Calculation were made on Excel to
turn raw data into station locations. The map below
shows the received stations. The circle size indicates
the average signal strength from the region. The signals
from North America were good compared to those of much
closer European stations!
During the Spring Stew Perry, I was operating from 3V8SS
using an Inv-V for 160 while listening on the remote
beverage. European signals where clearly better on the
inv-V while no NA signal was heard on it. NA signals
were easily copied on the beverage.
Here below are two audio recordings of NA stations:
Later on, the ground spikes were replaced by 2m long
steel tubes set up on small cement blocks.
The SWR curve of the beverage is plotted using Rig
Expert AA-30.ZERO and was found as below:
Signal Source and F/B Check
used a signal source of about 0,5W at 1834.4 KHz to
check the front to back of the beverage antenna.
The distance from both ends of the antenna is about 470m
on the same line.
The signal source was powered by two 9V batteries and
the antenna consisted of a 2m wire.
When plotting the radiation pattern of the antenna on
MMANA at an elevation of 0.18 deg (corresponding to 470m
distance and 1.5m of elevation), the difference of Front
to Back was found to be around 8 db (See pattern plot at
SpectraVue has been used to record the FFT Spectrum from
RF Space SDR-IQ during the signal source transmission
for a later comparison of signal strength at the TX
According to the plots above, a difference of 7 db
between front to back can be noticed which is in line
with the plotted pattern at 0.18 degree (Blue line:
Front Signal, Red Line: Back Signal).
In order to check the maximum null, signal source should
be placed much higher in the air.