I discovered the Tomahawk quite by accident . I replicated it 3 times before I actually understood why it worked. It is a two band single feed line (75 ohm) antenna with a flat SWR and 2% to 3% reflected power.
What is it? Let's start with a 17 meter full wave delta loop fed near the top but not at the top. This is to obtain vertical polarization and lower angle of radiation. . The formula , as you know is 1005 / f. Mine was cut for 18.090 so we are looping about 53 foot closed loop fed with the braid of the coax on one side and the center conductor on the other with some kind of an insulator. No balun. Now because of velocity factor of wire and height above ground you will have to trim or add wire to resonance. I never build any antenna that I don't have to trim or add -- never!! Formulas get you close.
Now we have out 17 meter Delta loop mounted on a single support at about 30 feet at the apex. The corners are pulled out using weed eater line and tied off in my case to a fence on one side and a tee post on the other.
Not done. Lets now look at the full wave OCF (off center fed) diplole
This antenna actually has 3.4 dbi gain which is one 1.2 dbi more than a dipole. Note the formula of 936/f. looking a frequency of 14.025 is roughly 68 feet. Now , looking at the long radiator of the OCF --instead of having that in horizontal configuration ,let's put that in a Delta configuration. How long would that 3/4 wave delta be? 3/4 of 68 feet =51 feet . interesting ! Remember that our 17 meter delta loop was 53 feet . what if we added the quarter wave stinger to one side of the coax connection on the 17 meter delta loop?
When I did it, I got a big swr dip at 12.8 MHZ . Hummmmm? wonder if I shortened the stinger 2 feet ? Bang 14.050. Quick look at 17 meters -- still perfect resonance.
On 20 meters I did my reverse beacon test ( see my page on how to do that). I tested against a 40 meter loop that resonates on 20 meters . The new antenna on same station RBN ( 7 different stations) beat the 40 meter loop 96 total db s/n to 83!! Success,
I call it the Tomahawk because with the quarter wave stinger horizontal from the Delta -- it looks like one.
The above antenna also works very nicely on 15 and 12 meters with a 1.8 to 1 SWR. My Tomahawk is on 50 ohm coax and no balun!!
I have a three element triband beam at 40 feet . Of course The Tomahawk does not compare but I am amazed at the performance and receive characteristics of the Tomahawk. I can work the same DX ;however I might have to turn on the linear where the beam is with just 100 watts,
The Tomahawk delta is on a single support only 30 feet at the top and 12 feet at the bottom. This antenna would perform much better at 50 feet at the apex.
I have replicated this antenna on a rectangle 40 meter loop with a 66 foot stinger . It worked 80 meters perfect!! Then I replicated a 30 meter delta with a 60 meter quarter wave stinger. In fact the 60 meter stinger is attached to the one feed point of my two band delta loop ( see my article on that antenna) so I have 3 bands on one 75 ohm feed line.
Wire is fun. 73.
What is it? Let's start with a 17 meter full wave delta loop fed near the top but not at the top. This is to obtain vertical polarization and lower angle of radiation. . The formula , as you know is 1005 / f. Mine was cut for 18.090 so we are looping about 53 foot closed loop fed with the braid of the coax on one side and the center conductor on the other with some kind of an insulator. No balun. Now because of velocity factor of wire and height above ground you will have to trim or add wire to resonance. I never build any antenna that I don't have to trim or add -- never!! Formulas get you close.
Now we have out 17 meter Delta loop mounted on a single support at about 30 feet at the apex. The corners are pulled out using weed eater line and tied off in my case to a fence on one side and a tee post on the other.
Not done. Lets now look at the full wave OCF (off center fed) diplole
This antenna actually has 3.4 dbi gain which is one 1.2 dbi more than a dipole. Note the formula of 936/f. looking a frequency of 14.025 is roughly 68 feet. Now , looking at the long radiator of the OCF --instead of having that in horizontal configuration ,let's put that in a Delta configuration. How long would that 3/4 wave delta be? 3/4 of 68 feet =51 feet . interesting ! Remember that our 17 meter delta loop was 53 feet . what if we added the quarter wave stinger to one side of the coax connection on the 17 meter delta loop?
When I did it, I got a big swr dip at 12.8 MHZ . Hummmmm? wonder if I shortened the stinger 2 feet ? Bang 14.050. Quick look at 17 meters -- still perfect resonance.
On 20 meters I did my reverse beacon test ( see my page on how to do that). I tested against a 40 meter loop that resonates on 20 meters . The new antenna on same station RBN ( 7 different stations) beat the 40 meter loop 96 total db s/n to 83!! Success,
I call it the Tomahawk because with the quarter wave stinger horizontal from the Delta -- it looks like one.
The above antenna also works very nicely on 15 and 12 meters with a 1.8 to 1 SWR. My Tomahawk is on 50 ohm coax and no balun!!
I have a three element triband beam at 40 feet . Of course The Tomahawk does not compare but I am amazed at the performance and receive characteristics of the Tomahawk. I can work the same DX ;however I might have to turn on the linear where the beam is with just 100 watts,
The Tomahawk delta is on a single support only 30 feet at the top and 12 feet at the bottom. This antenna would perform much better at 50 feet at the apex.
I have replicated this antenna on a rectangle 40 meter loop with a 66 foot stinger . It worked 80 meters perfect!! Then I replicated a 30 meter delta with a 60 meter quarter wave stinger. In fact the 60 meter stinger is attached to the one feed point of my two band delta loop ( see my article on that antenna) so I have 3 bands on one 75 ohm feed line.
Wire is fun. 73.
Neat antenna,kinda a weird accidental hybrid, Good work.
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