Practical Antenna Modeling - Part 20 Radials continued
January 27, 2009 1:47 amCreating the Radial Set
We’re going to take a look at a very simple vertical antenna in free space and use the features of EZNEC to add radials to the model. Note that the radiator is along the Z axis starting at the origin (0,0,0).
FIRST … I’ll add the single simplest radial I can to the model. in this case, I chose to add one along the Y axis from (0,0,0) to (0,50,0) or a 50 foot radial wire.
In the WIRES window, I can now use the ‘CREATE’ menu item and select ‘RADIALS’
This bring up the ‘CREATE RADIALS’ window. I get to specify the prototype group. In this case, I’ve selected just a single wire, but I could have had more than one. I also tell the program what the TOTAL number of radials is.
IMPORTANT: We’re entering the total number of radials, not the number of new ones we want to add. I’ve seen a number of students make this mistake thinking they are entering the number of radials to generate and not the total number that will be present when generated.
When I click OK, the program automatically creates additional radials to match the prototype spread out around the zero point. With 4 radials, this is pretty simple since each now goes along an axis:
The antenna now looks like this:
If I’d said that I wanted 8 total radials, I would have gotten this wire table:
You’ll notice that it automatically adjusts coordinates so that the radials come out properly. If you computed the length of each radial (numbers 3, 5, 7, & 9), you’ll find they’re all 50 feet long. So the radial system is now spread out around the antenna like this:
4 Responses to “Practical Antenna Modeling - Part 20 Radials continued”
I just discovered your site yesterday and want to thank you for allowing me to join your group. I’m not yet familiar with your protocol and procedures and not sure how to email you.
I found the earlier Parts on the Inverted L very interesting since I just put one up on 160m. Is it permissible to ask questions about earlier posts at a later date or should the comments only be made at the time the Part is published?
Also, is there a way to direct an email to an individual or two and not bother those in the group who may not be interested in that particular subject.
Frank,
Ask any questions you like. I respond to any questions as quickly as I can. This is a continuing series I’m writing, so you’ll see more coming up. I’m working through things slowly and some questions get asked directly without being posted, so some of the posts are driven by these ‘off line’ questions as well.
ADDED: I forgot to respond to the question about contacting individual members. There is no way through the group itself. Member’s email addresses are private and we don’t give them out. There is no objection to making contact and having people exchange their email addresses themselves, but we don’t want to give a spammer access to email.
Terry
Terry,
Thanks for your response. Now that I know my comments won’t be automatically posted for all to see, I won’t be as reluctant to ask a question.
Although I’ve had EZNEC for many years, all I ever did was very simple modeling of dipoles and yagis that I was interested in, and didn’t take the time to get a basic knowledge of modeling fundamentals. I’m going to review the basic QST articles you suggested, and then go back and start work on Part 1 of your series.
This is quite an undertaking, and I can see how it is going to take a good deal of time and effort on your part, so once again, thank you for your assistance.
Frank
Thanks Frank,
There are two ways to ask questions … one is here on the blog and another is in the yahoogroups mailing list. I review all posts before I allow them to go up because I’ve been hit over and over by spammers trying to get their messages posted. If someone wants to post here, it’s got to be on topic and not about online pharmacies or viagra :o)
Feel free to open a discussion anywhere and in any post. I’ll respond to any I find.
Terry
Care to comment?