I have got
a radio telephone
DAEWOO DWP-5000 working
in a range 900-MHz at the radio market in Kiev (see Figure DAEWOO DWP-5000).
I checked up the phone with its antennas. I could reach only 300-
350 meters when the phone saw the radio base. I need 2 kms communication
range. I decided to increase the communication range of my radio
phone by using an effective antenna. By the way, the antenna placed
at the base was made as a steel spiral, located into a rubber
tube (see photo Base Antenna).
The length of the antenna was 4 centimeters.
for my phone I decided to use well known in the former USSR so-called
antenna Harchenko. The antenna has a wide range and can work at
the range of 886 – 931- MHz
with a low SWR.
Do not forget,
transmitting and receiving frequencies differ
each other to 45- MHz at the 900- MHz phones. Antenna Harchenko
was calculated by
Antenna Simulation Program MMANA. Parameters of
the antenna are shown below. Left
diagram is a section of the volumetric diagram directivity of
plane X-Y at a zenith corner of the maximum radiation.
The right diagram
is section of the volumetric diagram directivity of plane X- Z.
Also at the right down corner of the pictures is a table with
antenna impedance. (see Figures: Schematic of the Antenna, Antenna Z, Antenna
SWR, Antenna Pattern)