[K3PZN-List] another antenna question

[Philip Karras]

Hi Ray,
 
First let me direct you to a good site: http://www.hamuniverse.com/n4jaantennabook.html
Understanding Antennas For The Non-Technical Ham
A Book By Jim Abercrombie, N4JA
(Jim Abercrombie 4ja at prtcnet.com)
His explanation of a Bazooka antenna is rather good. He also comments about the results of ARRL tests of the antenna.
 
"The double bazooka is claimed by its users to be broad-banded, a quality especially interesting for those hams operating on 75/80 meters. Tests done at the A.R.R.L. have shown the double bazooka is only slightly more broad-banded than a regular dipole, probably due to the use of a large conductor (coax) for the center part of the antenna. The double bazooka will not transmit its second harmonic, and its users say it does not need a balun. Other users say it is quieter than a regular dipole."
 
When I looked it up I said that this is something like a folded dipole with tails added, I wonder what adding tails to a folded dipole will do? I'm really going to have to learn to use EZNEC!
 
Folded dipole: Total Length = 1 wavelength, then fold it:
+-----------------------------------------------------------------------------+
|                                                                             |
|<-------- ~1/2 wavelength --------->    <--------- ~1/2 wavelength --------->|
|                                                                             |
+------------------------------------+  +-------------------------------------+
                                     |  |
                                     |  |
                                     |  |
                                     |  |
 
Folded dipole with tails: (Top is the "folded" part)
-----+-------------------------------------------------------------------+-----
     |                                                                   |
     |                                                                   |
     +-------------------------------+  +--------------------------------+
                                     |  |
                                     |  |
                                     |  |
                                     |  |

The disadvantage of the bazooka is that the folded part of the antenna is hidden from the RF coming from the stations so it does you no good at all. Being inside the shield (the transmitting & receiving parts of the bazooka antenna is also why it probably does not transmit on it's second harmonic. - I consider this a big disadvantage over a standard dipole. I like to get as much bang for my buck as possible so using an 80 m dipole on all bands with a tuner is a BIG advantage to a cheap ham like me. Much less time & effort & money to make one dipole & use it with a tuner on all bands than to make a separate bazooka for each band. IMHO

You can get the broader bandwidth on a standard dipole by using the same method as here - use the coax shield as the radiating/receiving part of the dipole. It doesn't look like there is anything else in the design that causes it to have a slightly wider bandwidth. Or, go with less expensive 300 or 450 ohm ladder line and tie both wires together as the elements, using 450-ohm ladder line would have an even wider bandwidth since it's spaced even further apart.
 
As for quiet I think you hit the nail on the head, it is quiet at the expense of the signals. In other words you've widened the bandwidth and put cotton in your antenna ears at the same time. It seems like a win-lose situation to me.
 
Why not just make a dipole out of coax using only the shield part or as I suggested using 450-ohm ladder line to get the broader bandwidth? Try disconnecting the center of the coax from the antenna so it is just a dipole and see what happens to the ears.

 
73 de KE3FL,
Phil
AEC Carroll County
OES, ORS, & VE
http://cs.yrex.com/ke3fl
http://www.qsl.net/caret


----- Original Message -----
 
Date: Sat, 4 Aug 2012 01:11:30 -0400
From: "Ray Wright" <razor42 at hughes.net>
Subject: Re: [K3PZN-List] another antenna question
To: "Carroll County Amateur Radio Club" <k3pzn-list at mailman.qth.net>
Message-ID: <B68F5077C507486E9854277D0384452A at RayPC>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
    reply-type=original

hi Curt ....

well using the bazooka in the inverted V to act like a vertical and see what 
we can hear.   It is quiet i will give them that but almost too quite as it 
knocks out signals you want to get.  still fooling with it.....
Kerri and i are going to berryville maybe pick up a 1/1 balun there.

thanks Ray