June 15, 2007
Today I tested a new saltwater antenna. It is fifteen feet tall, made from PVC pipe, and is filled with a calcium chloride solution. The ionic liquid is made from Prestone's "Driveway Heat" ice melter at the rate of 2.5 pounds per gallon of water. Pictured below is tonight's setup in the front yard. The PVC is supported by the bottom sections of an MFJ 10-meter pole slid over a stake.A stainless steel bolt in the bottom cap acts as a probe into the ionic liquid. For a ground system I used 16 radials: eight at 12.5" and eight at 14 feet in length.
At the bottom of the page is a graph of the R, X and SWR values as measured by an MFJ 259B analyzer.
I had only a brief time to operate, but managed a QSO with Bob, KA6LA in Arizona, on 20 meters around 0000Z. Then I tuned up on 17 meters and found Randy, KK7TV, also in AZ. I heard a 9Y4 station but never broke the pileup. Later in the evening (0450Z, nearly 11:00 p.m. local time and after family obligations were finished) I went back outside and made contact with Ed, NX7TT, in Idaho on 20 meters who reported my 5 watt signal was 5x5 to his 58-59. The Solar Flux was 69, and the K index was 3. This, coupled with the close proximity to the house and two large trees all within 10 feet of the antenna made for a less-than optimal setting, but it was a good evening to be outdoors.
Below is a graph of the analyzer readings from 10 through 18 MHz. With a manual tuner I was able to match the antenna from 10 through 21 MHz. I am not at all sure how to interprete the readings, as saltwater is more of a semiconductor than copper wire. The SWR values are graphed x10 to better fit the chart. Best SWR without a tuner was 3.0.
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Today I tested a new saltwater antenna. It is fifteen feet tall, made from PVC pipe, and is filled with a calcium chloride solution. The ionic liquid is made from Prestone's "Driveway Heat" ice melter at the rate of 2.5 pounds per gallon of water. Pictured below is tonight's setup in the front yard. The PVC is supported by the bottom sections of an MFJ 10-meter pole slid over a stake.A stainless steel bolt in the bottom cap acts as a probe into the ionic liquid. For a ground system I used 16 radials: eight at 12.5" and eight at 14 feet in length.
At the bottom of the page is a graph of the R, X and SWR values as measured by an MFJ 259B analyzer.
I had only a brief time to operate, but managed a QSO with Bob, KA6LA in Arizona, on 20 meters around 0000Z. Then I tuned up on 17 meters and found Randy, KK7TV, also in AZ. I heard a 9Y4 station but never broke the pileup. Later in the evening (0450Z, nearly 11:00 p.m. local time and after family obligations were finished) I went back outside and made contact with Ed, NX7TT, in Idaho on 20 meters who reported my 5 watt signal was 5x5 to his 58-59. The Solar Flux was 69, and the K index was 3. This, coupled with the close proximity to the house and two large trees all within 10 feet of the antenna made for a less-than optimal setting, but it was a good evening to be outdoors.
I waited too long in the evening to take this photo, but it shows the small front yard.
Below is a graph of the analyzer readings from 10 through 18 MHz. With a manual tuner I was able to match the antenna from 10 through 21 MHz. I am not at all sure how to interprete the readings, as saltwater is more of a semiconductor than copper wire. The SWR values are graphed x10 to better fit the chart. Best SWR without a tuner was 3.0.
Here is the stainless bolt that acts as a probe into the liquid and as a place to attach the feedline.
Credit goes to David Hatch, N9ZRT, for the creation of the ILA concept.
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