Tuesday, August 27, 2013

Loop Calculator One: Update 1.0228

The latest update to Loop Calculator One includes various cosmetic updates to improve readability and understandability.

For those new to Loop Calculator One, the program will display detailed information about coils, including accurate inductance for short and long coils of many types. It is especially tailored for inductance calculations of polygonal-shaped mediumwave receiving loops.

The original Loop Calculator One article was published on RADIO-TIMETRAVELLER in March, 2012.

For further information on loop calculations see the Loop 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 LoopCalculatorOne.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. Also included is an American Wire Gauge chart showing wire diameters.

Click image to enlarge.


Stephen said...

Hi Bill,

This is an interesting program, based on the few minutes I've played with it a little. :) If I wanted to calculate coils, etc. for ferrite loopstick or ferrite sleeve loop antennas, how would I do that? (I'm thinking FSLs like the ones Gary DeBock builds, although mine would likely be much smaller and cheaper - for example one of my smaller ones might fit inside a hollowed out ipod shuffle.)

Also, what would you say would be the minimum loop I'd need to match the gain I've been able to obtain from a combination of Select-A-Tenna + utility groundwire?

A few examples:

760 KFMB - PL-398mp + SAT+Util - 7.2mi SE of TX - 2013-05-06 22:02 PT
760 KFMB (+1520,3040) - PL-398mp barefoot - ~85 ft E of center tower - 2013-05-01 23:11 PT
KFMB's SAT+Util strength in the 1st one is the same as their barefoot strength in the second.

1170 KCBQ - PL-398mp + SAT+Util - 9.2mi S of TX - 2012-04-06 16:00 PT
1170 KCBQ - PL-398mp barefoot - ~300ft WSW of far west tower - 2011-11-03 0749 PT
In these two, KCBQ's SAT+Util strength in the 1st is somewhat stronger than their barefoot strength in the 2nd.

The next several are comparisons of barefoot and SAT+Util reception on the PL-606, from the same place for each video. (Some also include SAT only and maybe Util only.)

From 33.3292, -117.0006, recorded 2012-02-03 14:13-14:25 PT:

1110 KDIS - BF ~19 dBu - SAT+Util ~71 dBu - gain ~52 dB
830 KLAA - BF ~35 dBu - SAT+Util ~87 dBu - gain ~52 dB
640 KFI - BF ~30 dBu - SAT+Util ~82 dBu - gain ~52 dB
600 KOGO - BF ~26 dBu - SAT+Util ~79 dBu - gain ~53 dB

1550 XEBG - BF ~29 dBu - SAT+Util ~86 dBu - gain ~57 dB
This one was recorded 2012-01-20 14:21 PT in my front yard.
A couple other times at the same spot, I've briefly seen 98 dBu and heard a blip of overdrive/distortion on-channel (then it settled down to the mid 80s). This was done by tilt-nulling the radio near the SAT+Util, then quickly "snapping" it into strong signal position, timing it so I could get a reading before it desensed and refreshed.

If possible, I'd like to build one that could:
* have as much gain as (or more than) XEBG or KFMB (whichever is higher)
* sharp enough skirts that 1st-adjacents, including if I'm trying TP/TA splits (that would be as strong, barefoot with the internal antenna removed, as the example of KCBQ+SAT+Util near their TX), would be made to seem like they're off the air, while still having audio like the Boston More Than A Feeling AM Stereo 1242 JOLF video on youtube. :)
* reasonably inexpensive for the parts (like around $30-70 - this would dis1ualify Gary's FSLs - some of those run $500+!)
* could be folded up when not in use and fit in my Jansport Odyssey backpack, and could quickly (~30-90 seconds) be set up and taken down.
* Bonus points for still working somewhat when folded up, even if not at full potential, so long as it's still equal to just the SAT. :)
I also would like to be able to do LW DXing, aiding the PL-380, PL-606 and PL-398mp. Barefoot they're quite deaf - a local DGPS station on 302 kHz just 18.5 mi WSW of me barely registers over 15 dBu.


Stephen said...


As for smaller antennas...

If I wanted to replace the internal antennas of the PL-380, SRF-M37W (mine has an aftermarket AM filter), or SRF-59, how would the performance of the following options comppare?
* standard ferrite loopstick, properly designed for its size, taking the entire internal cabinet dimension (or for the PL-380, the sbort side, enabling it to be used in vertical orientation, better able to fit in my Levi's front jeans pocket)
* air-core loop wound around the perimiter of the case, inside
* ferrite sleeve loop, again wound around the perimeter. (the individual rods/bars may only be 7-10mm long, or whatever would fit in the case)

Also what would I need to be able to bring in, with a listenable splatter/desense-free signal, 1180 KERN from here at midday in summer, or 1440 KUHL (under KFNY) or 1290 KKDD at my grandma's house (1/3mi SE of 1430 KMRB and 1300 KAZN)?
By beating another radio's local oscillator, I can detect their heterodynes, but otherwise it's all splatter from the local adjacent pests, even on the Tecsuns with the ±1k BW. I'm about 2x past KERN's 0.15mV/m contour per radio-locator. My grandma is right near KKDD's 0.15mV/m contours, about halfway from KFNY's 0.5mV/m to 0.15mV/m, and ~2.4x past KUHL's 0.15mV/m. At my house, I did hear somewhat listenable audio on the PL-606 from KERN one time when KCBQ was off the air. (I was still getting desense from 1130 KSDO, though.)

73, Stephen


Hi Stephen,

Thanks for your comments.

Unfortunately, ferrite-based coils are calculated using entirely different formulas than the formulas used for standard air-based coils. There are even differences in the formulas between very small air coils and larger polygonal coils "passive air loops". And differences again for spiral-wound and solenoid-wound air loops. Ferrite coils would be best be made into a separate program.

In order to port Loop Calculator One to Android, the software would have to be totally rewritten. And for me, that would entail learning a new language and how to write for Android devices. Here is your chance to shine!

A Select-A-Tenna is about 12 or 13 inches in diameter as I recall. Hooking it to a utility ground wire is a different animal all in itself. I'm not sure how one could correlate a larger loop's gain with that. Too many variables - like the length and location of the ground wire, pattern skewing, not withstanding the possible noise pickup factor from utility services. You are mixing apples and oranges by combining the loop and ground wire. ;-) Too many variables to deal with. Maybe one of Gary's 9 foot loops?

All I can say about building passive loops is experiment! You will learn something and have fun in the process. Remember, bigger is better. If I was to guess at rough equivalency, my experiments show an 18-24 inch passive loop to be roughly equivalent to an 8 inch ferrite rod. Selectivity skirts are variable depending on turn spacing, loop size, number of turns compared to capacitance, many things.