|Animation - One of my popular high performance yagi designs - 4 x WS718562 432MHz yagis seen in 4nec2|
|4WS718562.nec analysis with Arie Voors free & powerful 4nec2 (NEC based antenna modeler & optimizer)|
G4CQM was the original founder of PowAbeam Antennas way back in early 1994, handing over the reins to Roger Banks GW4WND of The DXShop (ready made yagis) and Richard Mason G6HKS (kits and parts) during 2012.
This Web site contains the official repository of the PowAbeam Antennas yagi designs along with specifications for the ready made yagis sold by The DXShop...
|6M 50MHz, 4M 70MHz, 2M 144MHz, 70cm 432MHz, Amateur Radio Bands, Yagi Designs|
Derek G4CQM (formerly G8CIW) celebrates more than 50 years as a licensed Radio Amateur, first active back in early 1969... I've always had a passion for long distance (DX) VHF communication... If you want to work some DX then the best and first place to start with is your antenna!
Derek Hilleard G4CQM
|Animation - DL6WU directive for mounting parasitic elements on the boom which requires that|
each element is raised more than the boom radius (r) above boom then its proximity has no effect...
|Interesting to see that as elements move closer to the boom there is no impact on performance provided|
that the DL6WU directive is adhered to... Symbolic dimensions makes easy work of running this test!
I designed the unique PowAbeam ParAclips to solve the parasitic element mounting problem, to be used at 144MHz and higher... Parasitic elements are so high above boom, constructed to conform to the DL6WU directive for mounting parasitic elements on the boom which requires that each element is raised more than the boom radius (r) above boom. As a result Free-Space dimensions can be taken direct to the boom. This has a clear advantage in providing an accurate solution to the age old problem of how to mount your elements without needing any compensation!
| WS718562_boom.nec |
|Unique PowAbeam ParAclips solve the parasitic element mounting problem!|
ParAclips are made of tough UV stabilized Polypropylene. They are transparent to RF and don't get warm in a microwave oven test! Holds 3/16 Inch (4.7625mm) Imperial size or 5mm Metric OD rod parasitic elements and purpose designed to sit on 3/4 Inch (19.05mm) square section or a range of round boom sizes.
Contact Richard Mason G6HKS (kits and parts)
|Marcos PY1MHZ (Brazil) builds 144MHz 14 ele G4CQM yagi...|
I mainly use two types of antenna file for presentation on the Internet, they are, the .ANT and .nec file. Both are text file format and can be simply opened and inspected with a web browser or good text editor.
|6M5N50LY symbolic dimensions||6M4WB numerical format|
Popular Amateur Radio antenna software uses the Cartesian coordinate system to refer to points in space. X and Y are in the horizontal plane and Z is height. If you think of +X as north, then +Y is west. Most Hams tend to use numerical file format seen in 6M4WB example above. However, with larger yagi designs it's very easy to make mistakes, and when experimenting with stacking distances becomes very tiresome! On the other hand using symbolic dimensions/expressions as seen in 6M5N50LY example above it's easy to make dimension changes and avoid mistakes, try and see for yourself...
The following list of antenna software is compatible with the .ANT file format and symbolic dimensions/expressions...
The Numerical Electromagnetics Code (NEC) was developed (January 1981) at the Lawrence Livermore National Laboratory in California (USA), sponsors included the Naval Ocean Systems Centre and Air Force Weapons Laboratory. It was clearly intended in the first instance for professional use by those sponsor government organisations and was not developed as an amateur program!
The current version of NEC/MOM is due to extensive work carried out by Messrs G.J. Burke and A.J. Poggio.
NEC-2 is user-oriented, the computer code intended for analysis of the electromagnetic response of antennas and metal structures. There are several versions of NEC, NEC-2 was released to the public and is now available on most computing platforms.
NEC-2 has been used by several software developers in their antenna software as a reference and method of providing calibration.
Other EM (electromagnetic modelling) software based on 'mesh engines' such as FEKO EM, Ansys HFSS, Sonnet EM are available at high cost, this does not guarantee accuracy, there is no subsitute for real world testing...
During my time when I was self employed trading as Antenna Designer UK I would often work alongside John Wilson G3PCY at the local UKAS Accredited Antenna Calibration facility in Bideford Devon now run by Eurofins ETC.
|Single CQM10DX at 7M above ground seen in 4nec2||2 x CQM12UX at 20M above ground seen in 4nec2|
|Note that in the two examples above forward gain is subject to enhancement from ground gain.|
Amateur Radio stations will need to carefully consider the implications of OFCOM's proposals and changes to the licence, my own thoughts can be seen here!