This 3-element cage monopole is 3-wire antennas in parallel, spaced 1.5″ apart in a triangular vertical pattern, lifted toward the ceiling by a 3-leg bamboo tower rising from a triangular particle board base. At the top a triangular support for the wires is built from 3-corks stuck together with round tooth-picks and lightly glued to the top of the bamboo struts. The wires hang and at the bottom are held in place by a second triangular arrangement of corks & tooth-picks, below which the 3-wires flow together at a solder junction and are attached to a Wholehouse 2.0 with a clip-lead from the short antenna lead. The transmitter hangs below the antenna wire assembly by means of a plastic sock-hanging hook, large paper clip formed into a triangle keyed into the Wholehouse belt clip.
Operating frequency is 107.1mHz half-wave 55.14055″ antenna length.
On the open carrier I distinctly hear the 100kW station at 107.9mHz, whose transmitter is about 2-miles away. Perhaps my wires are cut a little short, and maybe if lengthened the unwanted signal might de-tune.
Of course putting 3-verticals in parallel lowers the impedance of the antenna, and the actual impedance of the Wholehouse Output is unknown.
Of course the advantage of a cage monopole is to provide a wider bandwidth antenna, but I’m not sure that it improves the outreach.
The reception meter on the Techniques Tuner, some 75 away, is 3.25 on a scale of 5.
C.Crane Plus located 12-feet away full meter reading.
Grundig portable FR-200 with antenna folded, good signal to 30-feet.
I would like also to have horizontal polarization, but how can this be done?
Horizontal Currents
Question: I would like also to have horizontal polarization, but how can this be done?
It is not too difficult. You need to get some electrons moving horizontally in your antenna system. From your description, a few radials attached to the top should work. If you want an omni pattern four should suffice. The length wouldn’t be critical but you should shorten the vertical elements a bit to compensate.
I am interested in your thoughts when you chose a 1/2 wave radiator since these, with no ground plane, present a high Z load to the transmitter.
Neil
Wavelength Thoughts
The Wholehouse 2.0 with a 1/4-wave antenna is so puny, I went to the next choice, 1/2-wave, which exactly fits the space available on the tower.
I will follow the instructions for horizontal rods up top, but instead of four, I’ll try three to meet up with the three verticals comprising the lower section. The top pieces will point out in a triangular pattern.
Where would a ground plane go? The antenna is way up high so it tips at the ceiling. Would the ground plane go on the floor? If it were at the bottom of the verticals it would jab someone in the chest (this is indoors right near a room-to-room doorway).
It’s now later in the day and the power meter on the Techniques receiver is holding at 3.25.
I tuned 107.1 in the car, and it was good for around 100-feet.
Another Version
Keeping all distances equal to the 3-element version described above, I put in a simple 1-element (1-wire) vertical antenna and observe a loss of .25 out on the Techniques tuner scale, with the new reading being 3.0 on a scale of 5.
Next stop, a 2-element version, and then finally, a 4-element cage monopole version.
2-Element Cage Monopole
The 2-element version of the cage monopole, amounting to two 1/2-wave verticals antennas side-by-side fed in parallel, demonstrates a slightly directional characteristic.
When the tower is rotated so that one vertical is closer to the test tuner than the other, the reading on the scale of 5 is 2.95.
When rotated so that both elements are equi-distant from the tuner, the scale reads 3.12.
What we have learned so far is that the 3-element version has slightly more output.
Now we need to try a 4-element version and, if the effective power continues to rise in small increments, do we try a 5-element?
I am not at all concerned about exceeding the Part 15 radiation limit of nominally 200-feet, as the Wholehouse 2.0 is so weak, at least operated indoors, that the signal outdoors is barely present.
The Final Stage
The 4-element cage monopole is now running, and the power level on the Techniques tuner is a solid 3.25 on a scale of 5, exactly the same as with the 3-element.
Eventually I’ll revert to the 3-element version because simpler is better, then begin work on the horizontal elements, which will be tricky, because they have to float out in open air.
Problem Not a Problem
Earlier I thought the test antenna at 107.1mHz was re-radiating a powerful station at 107.9, but when I looked into it it was certain FM radios mixing the signals, and simply lowering the receive antenna revealed a silent carrier coming from the experimental cage monopole.
Hangin’ Around
Hmm why not use a metal coat hanger cut to length and looped around a screw, cut four of these out of a couple metal coat hangers if you can find any. This is one thing that is nearly extinct around here but metal coat hangers are great for making antennas. I would sand the varnish off of them though. Once you have them fasten in place then bend them a bit to get the angle just right. Wielding rods work too but would be hard to make a loop at the end for a screw to hold them in place.
Like the Idea
Along with saving corks, bamboo and toothpicks, I luckily have a batch of wire hangers and like your idea of using those.
For the past 24-hours the 4-element cage monopole has been acting as the STL (Studio Transmitter Link) to send audio 60-feet to the tuner, then into 1550 AM SStran, and although the signal path is the same as my main walking path, the signal has been rock solid and never multi-paths while I stand, sit, move back and forth.