Updated 2017-03-07 22:48:27 by gold

## Introduction edit

gold Here is some eTCL starter code for a twin lead folded dipole antenna. The impetus for these calculations was checking calculations for a dipole antenna. Most of the testcases involve assumptions and rules of thumb.

The procedure starts with finding the radio wavelength in meters, wavelength = (velocity_factor*speed_of_light)/(megahertz* 1E6). The antenna length is set for half wavelength and is multipled by a correction factor for end distortion. The antenna height above ground is 2 wavelengths above ground.

# following statements can be pasted into eTCL console
``` set project 1.0
set wavelength [/ [* .95 300E6] [*  98.E6] ]   # 2.908 meters
set wavelength [/ [* .95 300E6] [*  57.E6] ]   # 5.0 meters
set wavelength [/ [* .95 300E6] [*  100.E6]]   # 2.85 meters```

### Testcases Section

In planning any software, it is advisable to gather a number of testcases to check the results of the program. The math for the testcases can be checked by pasting statements in the TCL console. Aside from the TCL calculator display, when one presses the report button on the calculator, one will have console show access to the capacity functions (subroutines).

#### Testcase 1

table 1printed in tcl wiki format
quantity value comment, if any
testcase number:1
98.1 :center frequency megahertz
1.0 :optional
1.0 :optional
2.90519877675841 :wavelength meters
1.452599388379205 :half wavelength meters
1.467125382262997 :corrected .5L antenna length meters or 57.18895412844037 inches
5.81039755351682 :height above ground meters

#### Testcase 2

 testcase number: 2 100.1 : center frequency megahertz 1.0 : optional 1.0 : optional 2.8471528471528473 : wavelength meters 1.4235764235764237 : half wavelength meters 1.437812187812188 : corrected .5L antenna length meters or 56.046317682317685 inches .5 : antenna lead meters 5.694305694305695 : height above ground meters

#### Testcase 3

table 3printed in tcl wiki format
quantity value comment, if any
testcase number:3
57.1 :center frequency megahertz
1.0 :optional
1.0 :optional
4.991243432574431 :wavelength meters
2.4956217162872156 :half wavelength meters
2.5205779334500877 :corrected .5L antenna length meters or 98.25282661996499 inches
9.982486865148863 :height above ground meters

### References:

• Wikipedia on dipole
• Antennas, see snowflake antenna, tikalon blog,
• May 16, 2016, Dev Gualtieri, excellent article

## Appendix Code edit

### appendix TCL programs and scripts

```        # pretty print from autoindent and ased editor
# Twin Lead Dipole Antenna calculator
# written on Windows XP on eTCL
# working under TCL version 8.5.6 and eTCL 1.0.1
# gold on TCL WIKI, 15dec2016
package require Tk
namespace path {::tcl::mathop ::tcl::mathfunc}
frame .frame -relief flat -bg aquamarine4
pack .frame -side top -fill y -anchor center
set names {{} {center frequency megahertz :} }
lappend names {optional, :}
lappend names {optional, :}
lappend names {answers: whole wavelength meters :}
lappend names {half wavelength  meters :}
lappend names {corrected .5L antenna length  meters: }
lappend names {height above ground meters:}
foreach i {1 2 3 4 5 6 7 8} {
label .frame.label\$i -text [lindex \$names \$i] -anchor e
entry .frame.entry\$i -width 35 -textvariable side\$i
set msg "Calculator for Twin Lead Folded Dipole Antenna
from TCL WIKI,
written on eTCL "
tk_messageBox -title "About" -message \$msg }
proc pi {} {expr acos(-1)}
proc calculate {     } {
global side1 side2 side3 side4 side5
global side6 side7 side8
global testcase_number
incr testcase_number
set side1 [* \$side1 1. ]
set side2 [* \$side2 1. ]
set side3 [* \$side3 1. ]
set side4 [* \$side4 1. ]
set side5 [* \$side5 1. ]
set side6 [* \$side6 1. ]
set side7 [* \$side7 1. ]
set side8 [* \$side8 1. ]
set megahertz \$side1
set conv_factor \$side5
set speedoflight 300E6
#set velocityfactor .87 ; alternate velocity factor
set velocityfactor .95
set wavelength [/ [* \$velocityfactor \$speedoflight] [* \$megahertz 1E6 ] ]
set halfwavelength [* \$wavelength .5 ]
set antennacorrection [* \$halfwavelength 1.01 ]
set heightaboveground [* 2. \$wavelength ]
set side4 \$wavelength
set side5 \$halfwavelength
set side6 \$antennacorrection
set side8 \$heightaboveground
}
proc fillup {aa bb cc dd ee ff gg hh} {
.frame.entry1 insert 0 "\$aa"
.frame.entry2 insert 0 "\$bb"
.frame.entry3 insert 0 "\$cc"
.frame.entry4 insert 0 "\$dd"
.frame.entry5 insert 0 "\$ee"
.frame.entry6 insert 0 "\$ff"
.frame.entry7 insert 0 "\$gg"
.frame.entry8 insert 0 "\$hh"
}
proc clearx {} {
foreach i {1 2 3 4 5 6 7 8 } {
.frame.entry\$i delete 0 end } }
proc reportx {} {
global side1 side2 side3 side4 side5
global side6 side7 side8
global testcase_number
console show;
puts "%|table \$testcase_number|printed in| tcl wiki format|% "
puts "&| quantity| value| comment, if any|& "
puts "&| testcase number:|\$testcase_number | |&"
puts "&| \$side1 :|center frequency megahertz |   |&"
puts "&| \$side2 :|optional| |& "
puts "&| \$side3 :|optional| |& "
puts "&| \$side4 :|wavelength meters| |&"
puts "&| \$side5 :|half wavelength meters  | |&"
puts "&| \$side6 :|corrected .5L antenna length meters or [expr \$side5*39.37008] inches  |  |&"
puts "&| \$side7 :|antenna lead meters |  |&"
puts "&| \$side8 :|height above ground meters|  |&"
}
frame .buttons -bg aquamarine4
::ttk::button .calculator -text "Solve" -command { calculate   }
::ttk::button .test2 -text "Testcase1" -command {clearx;fillup 98.1 1. 1.0 2.908  1.45 1.46 .5 5.8}
::ttk::button .test3 -text "Testcase2" -command {clearx;fillup 100.10 1. 1.0 2.85  1.425  1.439 0.5 5.7 }
::ttk::button .test4 -text "Testcase3" -command {clearx;fillup 57.10 1. 1.0 5.0  2.5  2.525 0.50 10.10 }

::ttk::button .clearallx -text clear -command {clearx }
::ttk::button .cons -text report -command { reportx }
::ttk::button .exit -text exit -command {exit}
pack  .clearallx .cons .about .exit .test4 .test3 .test2   -side bottom -in .buttons
grid .frame .buttons -sticky ns -pady {0 10}
. configure -background aquamarine4 -highlightcolor brown -relief raised -border 30
wm title . "Twin Lead Folded Dipole Antenna Calculator"      ```

### Pushbutton Operation

For the push buttons, the recommended procedure is push testcase and fill frame, change first three entries etc, push solve, and then push report. Report allows copy and paste from console.

For testcases in a computer session, the eTCL calculator increments a new testcase number internally, eg. TC(1), TC(2) , TC(3) , TC(N). The testcase number is internal to the calculator and will not be printed until the report button is pushed for the current result numbers. The current result numbers will be cleared on the next solve button. The command { calculate; reportx } or { calculate ; reportx; clearx } can be added or changed to report automatically. Another wrinkle would be to print out the current text, delimiters, and numbers in a TCL wiki style table as
```  puts " %| testcase \$testcase_number | value| units |comment |%"
puts " &| volume| \$volume| cubic meters |based on length \$side1 and width \$side2   |&"  ```