Tuesday, August 27, 2013

Field Strength Calculator One: Update 1.0054

The latest update to Field Strength Calculator One has corrected the About window and incorporated various cosmetic updates. Also included are further refinements to the accuracy of the field strength calculation and distances.

For those new to Field Strength Calculator One, the program returns expected received field strength in millivolts per meter and dBu (also known as dBµV/m), based on ground conductivity, earth dielectric and several other input constants. It also displays the distance to the radio horizon and the signal path loss in dB, along with several more technical parameters. The resulting output of Field Strength Calculator One should be accurate in most cases to a couple of percent in the longwave and mediumwave bands. It compares favorably to ITU program GRWAVE and currently available FCC Ground Wave Conductivity graphs.

The original Field Strength Calculator One article was published on RADIO-TIMETRAVELLER in December, 2012.

For further information on how field strength is calculated see the Field Strength Calculations Series previously published on RADIO-TIMETRAVELLER.


To download, see the link at the top of the right sidebar under LATEST PROGRAMS. The sidebar at the top right will have the most current link in case the program is updated. The link will change in the case of an update, so I would avoid copying and pasting it into a forum or other web page. Come to the main page of this blog instead.


Install is simple. Download the .zip file and unzip. Click on the FieldStrengthCalculatorOne.exe file to run. This program makes no registry changes and saves no data to your hard drive. It has been developed and tested in Windows 7. It should work fine in Windows Vista and XP environments, and Windows 8. It is written in the old standby Visual Basic 6.

Included in the .zip is a readme.txt file. Be sure to have a look.

Click image to enlarge.


Stephen said...

Hi Bill,

Is there a way this could be made to run on Android, either as an app, or on a website without requiring flash? I'm on my phone (Samsung Galaxy S Relay 4G running 4.1.2 Jellybean) MUCH more than I'm on a windows PC.

Also what's the progress being made toward being able to calculate multiple different conductivities along a path?
Would it be either...
including M3 data,
having several fields where the user puts in several conductivities to certain distances, or,
a few fields, where you put the strength at a particular distance, and the conductivity and further distance you want to calculate (and would have to repeat for each change in conductivity)? I wonder if this might get me by for now, although a combo of the 1st two would be preferred - a "standard" and "custom" option, I suppose. :)

And is it not possible to calculate near-field strengths, like in some of my examples (the ones where the radios are severely overloaded) in my comments to the loop calculator post?
And I'm just curious - there in Avon, do you have any locals that overload your radios (like the examples from the other comments when my PL-606 or PL-398mp indicate 95+ dBu) when you use your highest-gain antenna combinations? :)

73, Stephen


Hi Stephen,

Progress on the calculation of signal strengths along multiple and different conductivities along a path has been slow and has taken much of my time this summer. I have been at it since about May and have at least a couple of hundred hours in. I basically have the M3.seq conductivity map conquered. I had hoped to be able to add the data in for the R2.seq map (western hemisphere), but the data is in a different format, ambiguous, and hard to work with. Three+ years on one program (my plotting program, Radio Data MW, which is where this effort has been) is enough and probably too much. I need to move on with some new things in my life ;-) I have interests in a lot of areas, many of which may are not software or even computer-related.

Near field strengths, like those found within one kilometer and very near antenna towers might best be calculated using some of the formulas which are OSHA-related. I would Google and include the term OSHA and see what you get. You are in the area of "hazardous" exposure right next to a tower. OSHA does have some guidelines for this, I have seen them somewhere.



My worst overload problem is when I'm in Rochester, where I'm 1.2 miles from 5KW WXXI-1370, 1.6 miles from 5KW WHTK-1280, and 1.6 miles from 5KW WROC-950. Desense is very apparent +/- 50 KHz on the PL-380 and even worse on other radios like the Sony SRF-M37. My loops can actually help as they are directive. My PL-380 only registers to 63 dBu, and that is easily exceeded. 50KW WHAM-1180 out at about 12 miles just hits 63 dBu.