Ham Radio QSO Parties

A new twist… This simulation places an additional wire underneath the previous 40 meter dipole up 6 feet.

There has been much discussion about improving a dipole’s response by modifying the ground conductivity beneath it. Indeed ground losses are the main culprit is loss of efficiency. The lower the antenna the more the loss. So let’s just lay another 1/4 wave of wire on the ground underneath the active dipole element…

…BUT WAIT…

The EZNEC program I use to perform these simulations uses NEC2 for the actual antenna simulations. This imposes some restrictions on how close a conductor can be to the ground. After a read through the ample help provided by EZNEC these points became clear:

• NEC2 will not correctly simulate wires in the Earth
• NEC2 will not correctly simulate wires closer than about 0.005 of a wavelength
• Real/High Accuracy ground is the proper “Ground Type” for simulations like this
• NEC4 does simulate buried wires
• EZNEC does not support NEC4…
• …well not exactly. EZNEC supports NEC4 just fine, but you have to pay more for it plus pay the license fee for NEC4 itself.
• Thus, I use NEC2…
• Thus, I am simulating the extra wire about 1 foot above ground level

Here is the 40 meter dipole with the new wire beneath…

Let’s simulate 7200kHz and see what we have…

Well what to you know… this antenna pattern (in blue) finally beat the baseline antenna (in black) just a little bit. This is the pattern perpendicular to the antenna… or broadside.

Here is the pattern inline with the antenna…

Focusing only on the radiation perpendicular, or broadside, to the wire let’s have another look at the elevation pattern compared with not only the base line, but also with the original 6 foot high antenna without the reflector…

This shows quite clearly adding the reflector wire yields about 4 dBi gain straight up and out towards 45 degrees or a good 4.7 dB better than the same without the reflector wire.

The results also show a slight improvement over the 26 foot high Inverted V.

So given a choice which system would we pick. It depends on the available gear doesn’t it?

The inverted V requires a modest mast and some guying. The flat dipole requires two wires, two or three masts and associated gear.

The quest for the champion portable signal will help dictate your approach.

Don’t forget, this is not the very best signal possible. The conclusion post will summarize all simulated possibilities.