50 Ohm Coax Feed
Shunt Matching Coil
Loading Coil
30 inches long
Diameter 0.78 inches (20mm)
30 inches long
Diameter 0.78 inches (20mm)
10 Meter Telescopic Pole
After moving to temporary accommodation back in the UK, I decided to get back on the air and blow the cobwebs off the
Old Rig. I had always favoured 160 meters but with such a small domestic lot this was to prove a challenge. The only was UP!
Detailed in this narrative are the elements of my effort which has resulted in a portable and low-cost solution which you may find of interest.
The 160 meter loaded vertical antenna is constructed using an inexpensive Telescopic Fiberglass Fishing Pole 10m in length.
The lightweight construction make it easy to handle and self supporting offering minimal wind resistance. An ideal combination for portable use.
The Loading Coil is close wound directly onto the pole 6 feet below the antenna top and measures 30 inches in length and 20mm diameter at this section of the pole.
A lightweight wire radiator follows the length of the pole and is attached to the bottom of the coil, the radiator continues from the top of the coil to the high end if the whip.
The antenna itself is tuned to resonance at a frequency higher than the desired operating frequency, in this case 1.650mhz to allow fine tuning and impedance matching which is achieved using a shunt feed inductor which DC grounds the antenna and matches the termination impedance to 50 ohms.
To obtain resonance on other parts of the 160m band the coil needs to be marginally extended in length to lower the frequency or reduced to achieve a higher frequency match. The option is to extend or reduce the length of the top (whip) section to achieve the same result. This type of antenna needs to be tuned against ground and a system of ground radials of 60 feet in length is desirable to limit ground resistance loss.
An Antenna Analyser is a useful tool but the antenna can be adequately tuned with the aid of an SWR bridge and a "Suck It and See" approach.
Pictures and diagrams can be viewed by clicking the relevant links.
Old Rig. I had always favoured 160 meters but with such a small domestic lot this was to prove a challenge. The only was UP!
Detailed in this narrative are the elements of my effort which has resulted in a portable and low-cost solution which you may find of interest.
The 160 meter loaded vertical antenna is constructed using an inexpensive Telescopic Fiberglass Fishing Pole 10m in length.
The lightweight construction make it easy to handle and self supporting offering minimal wind resistance. An ideal combination for portable use.
The Loading Coil is close wound directly onto the pole 6 feet below the antenna top and measures 30 inches in length and 20mm diameter at this section of the pole.
A lightweight wire radiator follows the length of the pole and is attached to the bottom of the coil, the radiator continues from the top of the coil to the high end if the whip.
The antenna itself is tuned to resonance at a frequency higher than the desired operating frequency, in this case 1.650mhz to allow fine tuning and impedance matching which is achieved using a shunt feed inductor which DC grounds the antenna and matches the termination impedance to 50 ohms.
To obtain resonance on other parts of the 160m band the coil needs to be marginally extended in length to lower the frequency or reduced to achieve a higher frequency match. The option is to extend or reduce the length of the top (whip) section to achieve the same result. This type of antenna needs to be tuned against ground and a system of ground radials of 60 feet in length is desirable to limit ground resistance loss.
An Antenna Analyser is a useful tool but the antenna can be adequately tuned with the aid of an SWR bridge and a "Suck It and See" approach.
Pictures and diagrams can be viewed by clicking the relevant links.
Click links below to view images
70 inches
Top of Coil to
tip of Antenna
Top of Coil to
tip of Antenna
7" Shoulder to Coil
Pictures of the 160m Vertical
10 Meter Telescopic Pole
Diagrams of the Loading and Matching Coils
Click links below to view images
Graphic Results From Antenna Analyser
Click links below to view images
Live 'On The Air' Test Results
Click links below to view images
(Test Date: Sep 30 2014 at 18:52 hrs. Distance: 570 Miles - Daylight.)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
© vk6.org
