Welcome to VE7CA's Design Utility|
This RF Design Program is a tool that an amateur radio experimenter (homebrewer) should find helpful. When I started building the HBR2000, I was looking for something to help select component values when designing a VFO for a certain tuning range, bandpass filters and impedance matching circuit component values etc. I wanted a program where I would stipulate that parameters, such as: tuning range of a VFO or type of Filter, BW, Centre Frequency, how many sections and estimated Q of the coil etc. and the program would do the calculations based on the inputted parameters as well as produce a graph showing insertion loss in the case of a filter design. My friend had a program for design which I have found indispensable. We added and modified it during the development and continue to add new features when needed. It is very easy to use.
The program was not intended to be marketed thus it does not provide extensive instructions. It is just a tool so if you are not familiar with some design techniques, you may have to do some research first. It doesn't teach, it calculates and analyses commonly used circuits in Radio Design. I used it extensively for my designs. Outlined below is a brief set of instructions to get started:
Design Utility Tutorial : A Band Pass Filter
To design a Bandpass Filer (BPF), in the upper menu bar select "Tank". The next page will have several white boxes already filled in with numbers. You can change the numbers like the "BW" or "Fo" (which is the centre freq. of the BPF) but for now just leave it the way it is and over on the right hand side click the button that reads "Calc". When you click on "Calc", the program uses the numbers filled in the white boxes on the bottom half of the window to calculate component values displayed in the top half. For Analysis, the "Anal" button will toggle an analysis panel below that has text or graphic display of your filters response. The menu allows you to select "Ins" or "Ret" loss or both and Real or imaginary input impedance or both and "Exp" (export) tab-delimited text data. Now click on "Edit". This instructs the program to send the information that was just calculated to the Edit module and transfers you there.
In the Edit module you will see the component values for the BPF you designed. You can edit values or insert a new section at the begining or enable following sections upt 27 sections (for which you will need the "Long" format for editing. The "Dis/Ena/Clr Q, Q and Fo" inputs allow you to apply a "Q" at "Fo" to the inductors with the Set button. The "Cct" button toggles the top view between edit values and a schematic of what you are editing. Select ("View"), click "Go", and you can view a printable report with a circuit diagram of the BPF, a description of the filter and below, a graph showing the filter insertion loss in blue and the return loss in red. This can be printed and you can put it into you files for future reference.
Select "Help" to get help with all the features of this page.
The beauty of this program is that you don't have to be an electrical engineer to design sophisticated RF filters, etc. You decide what you need, input the parameters and the program does the calculations.
A unique feature of the RF Design Program is the ability to vary the overall Q of a filter or matching network to allow the use of standard manufactured component values. Typically in a filter this would be the capacitors. In the "Tank" page you will notice a little box in the lower left hand corner that is labeled, "Zrat" (Impedance Ratio), and the number in the box is 10. If you change 10 to 9.5, and check the box next to it, you will notice after clicking on "Calc" the values of the components above the circuit of the filter have changed. The capacitor value in parallel with the coil changed from 910 pf to 1000 pf which is a more easily sourced value than 910 pf. The point is that by making slight adjustments to the BW, Fo and Zrat values, you can often produce a filter that uses mostly standard value components and you know, before you build it, how it will turn out.
There are many other features that will become apparent as you begin to use the program. Good luck, good homebrewing and let us know what you think of the program.