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Author Topic: eznec program...  (Read 816 times)
K9SRV
Member

Posts: 121




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« on: March 07, 2013, 02:31:09 PM »

hey guys,
I recently put up a 170 foot 40 meter double extended zepp. It is made of 14 guage, DX Eng. coated
wire. Feed line is their 300 ohm twin lead, 88 feet long. The feed line comes directly into the shack,

where it may or may not be run thru a Balun Designs 4:1balun, depending on the band. The antenna is up
about 48 feet, and I was wondering if some kindly gent could plug that into the program so I can get a better
feel for where the gains and nulls exist.


Thanks in advance for any and all help/suggestions!

John
K9SRV
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N4UM
Member

Posts: 455




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« Reply #1 on: March 07, 2013, 03:17:16 PM »

At 7.1 Mhz it looks like you'll have two main lobes broadside (one on each side of the wire)  and two very small lobes off the ends.  The main broadside lobes will exhibit about 8 and a half db gain over an isotropic source at vertical angles of 40 degrees.  The broadside lobes are fairly broad in the vertical plane with significant radiation from a vertical angle of about 20 degrees thru 75 degrees.  It doesn't look like it will have too much in the way of low angle radiation.
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W5DXP
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Posts: 3546


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« Reply #2 on: March 08, 2013, 04:59:11 AM »

Above the 40m EDZ frequency, the radiation pattern will become cloverleaf. Here's a rule of thumb for you:

At ~1.3 times the EDZ frequency, a N/S or E/W oriented EDZ will be firing toward the NW/NE/SW/SE with four major cloverleaf lobes. For your 40m EDZ that frequency is ~9.6 MHz. So any ham frequency above 7.3 MHz will be tending toward an end-fire cloverleaf pattern with not much broadside radiation.

Above ~1.3 times the EDZ frequency, as the frequency is increased, the end-fire characteristics become more pronounced. At 4x the EDZ frequency, 10m is this case, a N/S oriented EDZ will be firing at N/S ~25 deg E/W with multiple lobes both in the horizontal and vertical radiation patterns.

Moral: Don't expect much broadside radiation when operating an EDZ above its design frequency.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
K9SRV
Member

Posts: 121




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« Reply #3 on: March 11, 2013, 08:45:52 PM »

thanks much to both you guys! your info gives me a better understanding of my antenna.

john
k9srv Wink
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