A program to measure and display the radiation pattern of a beam antenna
by G R Freeth (G4HFQ)
Web site: http://www.g4hfq.co.uk
Copyright 2002 - 2010 G R Freeth
Major change introduced in V3.1
Starting at V3.1 the program can use the signal strength acquired by an external power meter. This enables better resolution to be obtained for nulls below -30dB.
Two examples of such meters are based on the Analog Devices AD8307 Logarithmic Amplifier integrated circuit. Constructional details of such a device are available on the website of Thomas Scherrer, OZ2CPU http://www.webx.dk/
A kit form of the OZ2CPU design called the PM3 can be obtained from the Fox Delta site
David Bates, M0DFT has also produced a design specifically for PolarPlot delightfully known as PolarWatt. This design excludes the LCD and has a small range of commands to start/pause/stop readings.
By utilising an external wattmeter the need for a receiver connected to the sound card of your PC is eliminated, together with the complexitity of setting AF levels as well as RF levels.
Paragraphs that apply to using a sound card for input are marked **SC**. Paragraphs that apply to using a wattmeter for input are marked **WM**.
V3.2.7 Apr 2010 - Change: avoid opening a com port if FTBMeter, OZ2Meter or LP-100 in use
V3.2.6 Feb 2010 - Change: use a different OCX for accessing the Com ports which should improve compatibility with various USB/serial adapters based on the Prolific PL2303 chipset.
V3.2.5 Feb 2010 - Change: Use DirectX to access the sound card. This works under XP, Vista and Windows 7 but it does mean that you need to use the Windows volume controls instead of the slider on the main form. The Choose Input form has been re-designed to permit a separate Com port to be used for external triggering. The Mic and Line-In radio buttons now both mean 'use a sound card' for input.
V3.2.4 Aug 2009 - Bugfix: correct broken re-scale facility using the Rescale Plot slider
V3.2.3 Aug 2008 - Change: external triggering is now done from the CTS pin (8) of a 9-pin serial port. The program can now run on Vista if the sound card is not used to collect readings i.e. if an external power meter is used.
V3.2.2 July 2008 - Change: serial cables that have a level converter in them can now be powered from the RTS and DTR pins. Wrote the OZ2Meter program to display the serial output of an OZ2CPU digital power meter and also interface to PolarPlot. To use this interface method just choose LP-100-VCP, OZ2Meter or FTBMeter as the input source.
V3.2.1 March 2008 - Corrected a problem collecting readings when using an OZ2CPU digital power meter.
V3.2.0 June 2007 - Added the ability to read power levels using LP-100-VCP and FTBMeter V2
V3.1.0 September 2005 - added the ability to read power levels through the serial port.
V3.0.0 July 2005 - Free for personal use