[TowerTalk] Modeling "Bent Dipole" (and Conventional) 4-Squares, with Feed Systems

[Dan Maguire]

If you are thinking about building a 4-square array, or if you would like to do a more thorough job of analyzing your existing array, some recently-developed AutoEZ models may be of interest.  You can model vertical elements (on the left in the linked image below) or "bent dipole" elements supported by a tower or tall tree (below right).

http://ac6la.com/adhoc/4sq1.png

Then you can choose one of several different ways to feed the elements.  For example, if fed via a hybrid coupler (ala Comtek) the feed system can be modeled like this.

http://ac6la.com/adhoc/4sq9.png

With the elements and feed system both in the model you can run frequency sweeps to produce charts like this.

http://ac6la.com/adhoc/4sq13.png

For a different type of feed system you can produce simulated scope patterns to aid in measuring and adjusting the physical build.

http://ac6la.com/adhoc/scope5.png

This web page has all the details along with several model files.

http://ac6la.com/aecollection8.html

Neither the web page nor the models are for beginners.  In order to avoid getting hopelessly lost you should probably be familiar with Chapter 11 of ON4UN's Low-Band DXing 5th edition and/or with Chapter 8 in recent editions of The ARRL Antenna Book.

For those not familiar with AutoEZ this page has an overview.

http://ac6la.com/autoez.html

BTW, this post is not in response to the recent 4-square thread started by K4XS although it certainly is applicable to situations like his.  It's just a coincidence that Bill happened to post at about the same time I was wrapping up this collection of examples.

Dan, AC6LA
http://ac6la.com