Updated 2017-03-05 18:19:49 by gold

Introduction edit

gold Here is some eTCL starter code for calculating rectangular antennas from source frequency and other dimensions. The impetus for these calculations was designing rectangular antennas. Most of the testcases involve modeled data, using assumptions and rules of thumb .

The hentenna is a rectangular radio antenna with a cross bar tie for antenna leads. The original hentenna was designed for short wave frequencies on the order of 20 to 50 megahertz. Given a design frequency in megahertz, the various dimensions and proportions of the radio antenna are cut at heigth of wavelength(1/2), width of wavelength(1/6), and cross tie of wavelength(1/10). For simplified calculations, the radio wavelength in meters is equal to the speed_of_light in kilometers per second (300) over the radio frequency in megahertz. For an example of a receiving antenna for 100 megahertz and rounded numbers, the expressions below can be pasted into the eTCL console:

A rectangular radio antenna or hentenna designed for 99.7 mhz was built from half inch copper pipe. The antenna had sufficiently narrow beamwidth to distinguish between two FM broadcast transmitters about 10 degrees azimuth apart. The hentenna has a horizontally polarized output. The horizontal output cancels out some of the urban noise environment, since many broadcast signals are vertically polarized.
namespace path {::tcl::mathop ::tcl::mathfunc}
set megafrequency 100.
set wavelength [/  300. \$megafrequency ]
set wavelength2 [/ \$wavelength 2.]
set wavelength6 [/ \$wavelength 6.]
set wavelength10 [/ \$wavelength 10.]

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

quantity calc output hand solution comment
frequency megahertz 500. 500. input
antenna height meters .3 .91 output
antenna width meters.1 .28 output
tie bar height.06 .21 output

Testcase 2

quantity calc output hand solution comment
frequency megahertz 144. 144. input
antenna height meters .34 .314 output
antenna width meters1.04 .824 output
tie bar height.208 .219 output

Testcase 3

quantity calc output hand solution comment
frequency megahertz 99.7 100. input
antenna height meters 1.5 .31 output
antenna width meters.5 .11 output
tie bar height.3 .6 output

Testcase 4

quantity calc output hand solution comment
frequency megahertz 150 150 input
antenna height meters 1. .9 output
antenna width meters.3 .31 output
tie bar height.2 .25 output

Testcase 5

quantity calc output hand solution comment
frequency megahertz 50. 50. input
antenna height meters 3. 3.1 output
antenna width meters1. .9 output
tie bar height.6 .61 output

References:

• Antennas, Balanis

Appendix Code edit

appendix TCL programs and scripts

# pretty print from autoindent and ased editor
# rectangular radio antenna calculator
# written on Windows XP on eTCL
# working under TCL version 8.5.6 and eTCL 1.0.1
# gold on TCL WIKI , 9feb2014
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 {{} {frequency megahertz:} }
lappend names {answer: wavelength meters:}
lappend names {wavelengthsq  meters sq: }
lappend names {surface area meters sq: }
lappend names {answer: antenna height meters}
lappend names {antenna width meters:}
lappend names {cross tie height meters: }
foreach i {1 2 3 4 5 6 7} {
label .frame.label\$i -text [lindex \$names \$i] -anchor e
entry .frame.entry\$i -width 35 -textvariable side\$i
grid .frame.label\$i .frame.entry\$i -sticky ew -pady 2 -padx 1 }
proc about {} {
set msg "Calculator for Rectangular Radio Antenna
from TCL WIKI,
written on eTCL "
tk_messageBox -title "About" -message \$msg }
proc calculate {     } {
global side1 side2 side3 side4 side5
global side6 side7 testcase_number
global wavelength wavelength2
global wavelength6 wavelength10
global wavelengthsq surfacearea
global megafrequency
incr testcase_number
set megafrequency \$side1
set wavelength [/  300. \$megafrequency ]
set wavelength2 [/ \$wavelength 2.]
set wavelength6 [/ \$wavelength 6.]
set wavelength10 [/ \$wavelength 10.]
set wavelengthsq [* \$wavelength2 \$wavelength2 ]
set surfacearea [* \$wavelength2 \$wavelength6 ]
set side2 \$wavelength
set side3 \$wavelengthsq
set side4 \$surfacearea
set side5 \$wavelength2
set side6 \$wavelength6
set side7 \$wavelength10
}
proc fillup {aa bb cc dd ee ff gg} {
.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"}
proc clearx {} {
foreach i {1 2 3 4 5 6 7} {
.frame.entry\$i delete 0 end } }
proc reportx {} {
global side1 side2 side3 side4 side5
global side6 side7 testcase_number
global wavelengthsq surfacearea
global megafrequency
console show;
puts "testcase number: \$testcase_number "
puts "frequency (f) megahertz: \$side1 "
puts "wavelength (w) meters: \$side2 "
puts "wavelengthsq (w*w) meters sq: \$side3 "
puts "surfacearea meters sq (h*w) : \$side4 "
puts "wavelength/2 meters: \$side5 "
puts "wavelength/6 meters: \$side6 "
puts "wavelength/10 meters: \$side7 "
}
frame .buttons -bg aquamarine4
::ttk::button .calculator -text "Solve" -command { calculate   }
::ttk::button .test2 -text "Testcase1" -command {clearx;fillup 146. 2. 1. .35 1.0981  .34 .205 }
::ttk::button .test3 -text "Testcase2" -command {clearx;fillup 99.7 3.2 2.2 .75 1.5  .5 .3 }
::ttk::button .test4 -text "Testcase3" -command {clearx;fillup 500. .6 .09 .03 .28  .1 .06 }
::ttk::button .clearallx -text clear -command {clearx }
::ttk::button .cons -text report -command { reportx }
::ttk::button .exit -text exit -command {exit}
pack .calculator  -in .buttons -side top -padx 10 -pady 5
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 . "Rectangular Radio  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 (which 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   |&"

Initial Console Program

# pretty print from autoindent and ased editor
# written on Windows XP on eTCL
# working under TCL version 8.6.2 and_or eTCL 1.0.1
# gold on TCL WIKI, 15oct2014
#Console program for rectangular antenna (hentenna in Japan)
package require Tk
namespace path {::tcl::mathop ::tcl::mathfunc}
console show
proc antenna {args} {
foreach item \$args {
set megafrequency \$item
set wavelength [/  300. \$megafrequency ]
set wavelength2 [/ \$wavelength 2.]
set wavelength6 [/ \$wavelength 6.]
set wavelength10 [/ \$wavelength 10.]
puts " design fc mhz  \$megafrequency wavelength \$wavelength \
ant. height \$wavelength2 ant. width \$wavelength6  ant. tie_bar \
height \$wavelength10   \n "}}
antenna 50. 99.7 144. 150. 500.
# output
# design fc mhz  50. wavelength 6.0  ant. height 3.0 ant. width 1.0  ant. tie_bar  height 0.6
# design fc mhz  99.7 wavelength 3.009  ant. height 1.504 ant. width 0.501  ant. tie_bar  height 0.300
# design fc mhz  144. wavelength 2.083  ant. height 1.041 ant. width 0.347  ant. tie_bar  height 0.208
# design fc mhz  150. wavelength 2.0  ant. height 1.0 ant. width 0.333  ant. tie_bar  height 0.2
# design fc mhz  500. wavelength 0.6  ant. height 0.3 ant. width 0.099  ant. tie_bar  height 0.06