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Shunt Fed Tower Or If You Have a 50- to 60-Foot Tower with Something on Top, Here’s One Way You Can Get on 160M Z = 440 + j300

Shunt Fed Tower

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Shunt Fed Tower. Or If You Have a 50- to 60-Foot Tower with Something on Top, Here’s One Way You Can Get on 160M. My Situation. City Lot Tribander for 10, 15, and 20M Full-wave Delta Loop for 40M What to do for 160M?. Use Existing Tower. - PowerPoint PPT Presentation

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Page 1: Shunt Fed Tower

Shunt Fed Tower

OrIf You Have a 50- to 60-Foot Tower with

Something on Top, Here’s One WayYou Can Get on 160M

Z = 440 + j300

Page 2: Shunt Fed Tower

My Situation

City Lot Tribander for 10, 15, and 20M Full-wave Delta Loop for 40M What to do for 160M?

Page 3: Shunt Fed Tower

Use Existing Tower

http://www.qsl.net/w9rb/webdoc9.htm

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Why a Vertical?

Low take-off angle for DX Not a “space-saving” antenna Needs radials – the more the better Real World - 16 radials MINIMUM Ten 10-foot radials better than one 100-foot

Page 5: Shunt Fed Tower

Construction

Two wires 18 inches apart – fat conductor Inside wire 3 feet from tower Gamma section as long as possible Weather-proof plastic box at base

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Model

EZNEC+ Version 5.0 f=1.825 MHz Z=27.59 + j556

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EZNEC+ ver. 5.0

160M Shunt Fed 60Ft Tower

--------------- SOURCE DATA ---------------

Frequency = 1.825 MHz

Source 1 Voltage = 556.7 V at 87.16 deg. Current = 1 A at 0.0 deg. Impedance = 27.59 + J 556 ohms Power = 27.59 watts SWR (50 ohm system) > 100

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160M Shunt Fed 60-Foot Tower

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Measured

Autek Research RX VECTOR ANALYST Model VA1 f=1.825 MHz Z=440 + j300

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Matching Network

http://www.circuitsage.com/matching/matcher2.html

L = 15 uH C = 558 pF

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Matching Network

Source --------- L = 15 uH ----------- Load

|

C = 558 pF |

Gnd

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On The Air

Works okay for transmit Not so great for receive

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Possible Problem

Rotor in tower – controller may not be happy Solution disconnect rotator control cable before transmitting