# A Full-Blown 1/2 Wave Dipole?

Discussion in 'The Low Bands - 630/2200 Meters - VLF' started by WA2FXM, Nov 27, 2017.

1. ### W9XMTHam MemberQRZ Page

Below is a NEC4.2 plot of the elevation pattern fields at an h-distance of 1 mile from the base of a monopole, based on the same model parameters as in my original post above. A comparison is shown for that sector for the fields at 2 miles, also. These calculations include the surface wave, which is necessary to calculate/plot this scenario accurately.

Z = elevation in meters above a flat Earth, and E = field intensity in mV/m

Note that the two fields shown there have a ~1/r relationship, which is characteristic of a space wave. That relationship will be maintained for very low, but not zero-angle propagation paths reaching to, and reflected by the ionosphere.
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As a workaound, a Ø can be included in posts here by entering Alt+Ø216 using the number keypad.

2. ### K8JDHam MemberQRZ Page

Does this mean that the closer you get the stronger the field is ?
What is the size of the monopole ? By "T" that seems to mean it's less than a QW tall vertical with a two wire capacity hat ?
Not much info on the physical side of the antenna !
I want to build a real antenna.

3. ### W9XMTHam MemberQRZ Page

The T antenna dimensions are shown in the Comments section on the left side of the graphic in my original post about it.

4. ### W5DFNHam MemberQRZ Page

Okay, an update to the above post. About the time I posted this, we sold our home and moved to the property where we own and operate a private gun club. On October 10, Hurricane Michael paid us a visit setting back getting back on the air. This week I got my HF/VHF antennas back up and today I put up half of my 1/2 wave 630 meter horizontal dipole. Running the "live" leg was fairly easy. Take out four damaged oaks, and lay it out in a zigzag. The shield leg came straight down from the 20' feed point and is grounded to the tower base. Guess what it works!

6. ### AF7XTHam MemberQRZ Page

shunt feed ...

WA7PRC likes this.
7. ### WA7PRCHam MemberQRZ Page

The Wikipedia article leaves a lot of detail out. I toured NLK in the late 70s. Nominal output is around 1MW but, we were told they've had it cranked up to 2MW. When they do, Jim Creek is 1° warmer downstream. When we toured, the output current was 1296A. Into ZLOAD = 0.456Ω, that's "only" 766 kW. It made the broadcast xmtr (16 kW RFOUT) I worked on look like a QRP rig.