Tools

 

On-line technical Calculators and simple Design Tools

1) DC and AC resistance (due to skin effect) calculation of material in different shapes or forms, e.g. wire gauge, rectangular or round stock:

Wire/gauge http://www.cvel.clemson.edu/emc/calculators/Resistance_Calculator/wire.html

Rectangular http://www.cvel.clemson.edu/Emc/calculators/Resistance_Calculator/rect.html

Round http://www.cvel.clemson.edu/Emc/calculators/Resistance_Calculator/round.html

Using one of the above tools the ‘effective’ RF resistance of conductors used for the active (RF current carrying) portion of the antenna can calculated. Contrast this number with the RF Radiation Resistance for an idea of how effective your antenna may potentially be.

2) Skin depth calculator

http://www.rfcafe.com/references/calculators/skin-depth-calculator.htm

3) RF Tools, including: Attenuators, Filter design, LC resonance calculator, LC Balun Design, LC Matching Network Design, Path Loss Calculator, Skin Depth Calculator, Stripline Impedance Calculator, Smith charts, VSWR/Return loss converter, Wavelength calculator, Wilkinson power splitter Design

http://leleivre.com/rftools.html

 4) Interactive Dipole Antenna Analyzer/Simulator (Java app)

http://www.amanogawa.com/archive/Antenna1/Antenna1-2.html

Various parameters of a dipole (linear wire or cylindrical element) antenna can be chosen and the effects (such as feedpoint Z and gain) observed immediately in numerical form as well as graphically.

Note also if one makes a really, really fat dipole that the length of the dipole must be reduced if the antenna is to remain resonant (that is, zero reactance) …

5) Two-Dipole Phased Array Analyzer/Simulator (Java app)

http://www.amanogawa.com/archive/TwoDipole/Antenna2-2.html

Various parameters for a two dipole antenna array (fed from a common, coherent signal source) can be chosen and the effects (directivity, pattern) can observed immediately in numerical form as well as graphically. The pattern resulting effects for the cases of vertical stacking and horizontal placement are shown separately. No accounting for ground proximity (as will affect low band antenna performance as like hams use for 160 and 80 meters) are made, however.

This tool could come in handy to get a first-order look at the results of phasing two tuned Edginton Quarter-wave loops.


Data Tables

1) Conductor Bulk Resistivity & Skin Depth Table

http://www.rfcafe.com/references/electrical/cond-high-freq.htm

2) Wire Gauge Reference Table, including

AWG = American Wire Gauge, AWG is also known as Brown & Sharpe Gage.
SWG = Standard or Sterling Wire Gauge, a British wire measurement system.
BWG = Birmingham Wire Gauge, an old British wire measurement system that was                widely used throughout the world.

http://www.powerwerx.com/wiregauge.asp


Equations

1) Skin Depth (aka Skin Effect) as a Function of Frequency, Permeability, & Conductivity

http://www.rfcafe.com/references/electrical/skin-depth.htm


Small Transmit Loop Antenna Calculators

First, a ‘word’ about these calculator: I list them since they seem to be popular, although I have reservations on their ‘accuracy’ on estimating the performance of low band loops and loops approaching 1/4 wave (a QW) length in circumference.

I hope to list specifics why I have reservations on these calculators at some point. Suffice it to say at this point it is because I have seen different ‘numbers’ (actual antenna loop Z values) when building and testing QW and 1/8 Wave Edginton loops and comparing those numbers with the ‘numbers’ predicted by the loop calculators.

1) Small Transmitting Loop Antennas, (Magnetic Loop Antennas), Steve Yates – AA5TB

AA5TB spreadsheet – http://www.aa5tb.com/loop.html#cal

2) Magnetic Loop Antenna Calculator, 66pacific.com

http://www.66pacific.com/calculators/small_tx_loop_calc.aspx

Comment: See the blog entry (main page) on the non-agreement of this calculator with real-world testing results (on 40, 80 and 160 meter QW loops); suffice it to say this calculator should not be used for loops of 1/4 wave circumference (Edginton Quarter-wave Loop).


Misc Calculations and papers

1) Paper: “Q Factor Measurements on L-C Circuits” (incl. antennas)

http://www.arrl.org/files/file/QEX_Next_Issue/Jan-Feb_2012/QEX_1_12_Audet.pdf

See in particular, section 4 (a brief excerpt follows)

4 – Reflection Measurement Using an SWR Analyzer

This method has been recently developed to make use of an SWR analyzer, thus eliminating the need for the source-detector combination. Adjust the SWR analyzer to the resonant frequency of the circuit. The L-C circuit may be coupled to a link coil on the SWR analyzer, which provides variable coupling. … the amount of coupling is adjusted until the SWR drops to 1:1. The frequency is recorded as f0. Then the frequency is offset above or below f0 to obtain an SWR reading between 2 and 5. Now plug the new frequency and SWR values in the spreadsheet that I provide to calculate the unloaded Q factor.

2)

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