WQ6X Wangles a 160-Meter TRI-Square Vertical Array RBN Evaluation

After a recent QSO party weekend, I switched remote access to WA6TQT's STN-1 in Anza. 
to run a series of 160-meter directional-determination tests. At the last minute, it made sense
to write-up the experiment as a separate Blog.

With the recently refurbished 160-meter "TRI-Square" array, theoretically, there should be some
noticeable differences in signal levels between Northeast (N-E), Southeast (S-E) and West (W)
directions.

To measure this, test messages were sent on 1.816 (NE), 1.818 (SE) and 1.820 (W), then again
on 1.822 (NE), 1.824 (SE) and 1.826 (W).  Because I could not discern any real directional patterns,
I fed Ashley @A-I a the above picture of the antenna layout and the RBN stats from the above tests for a more detailed evaluation of the actually directional characteristics
of the TRI-Square.  Here are the essentials from her system evaluation:

"What you actually have is a 3-element vertical phased array for 160 meters, consisting of three 100-foot towers arranged in a triangular pattern, with three phasing lines running to a central relay/phasing mast. The towers themselves are the radiating elements."

"The antenna was configured in three directional modes:

• North-East
• South-East
• West

The reported Signal-to-Noise (dB) values provide a good indication of pattern performance."

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Northeast Mode

Strongest reports:

• K5TR (Texas) = 1465 miles
• N5RZ (Texas) = 1424 miles
• W7BP (Arizona) = 677 miles
• NG7M (Arizona) = 592 miles

Most reports are clustered eastward and northeastward.
The pattern appears reasonably directional with useful gain toward
Texas and the central U.S.

-------------------------

Southeast Mode

Interesting changes appear.

Strong reports:

• N5RZ = 16 dB
• ND7K = 30 dB
• W7BP = 8 dB
• VE7CC = 7 dB

The signal strengths toward Texas and the southern path improve somewhat.
This suggests the array is successfully rotating its major lobe

---------------------

West Mode

This is where the antenna becomes most interesting.

Reports include:

• N5RZ = 12 dB
• KW7MM = 21 dB
• ND7K = 26 dB
• KD7EFG = 16 dB
• N6TV = 17 dB

The western mode still produces strong reports while substantially
changing the geographic distribution

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The above tells me:

1. The phasing system is functioning correctly.
2. The three towers are contributing significant mutual coupling.
3. The pattern is rotating rather than simply switching feedpoints.

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What the Pattern Probably Looks Like

A 3-element vertical triangle normally produces:

• Broad cardioid-like lobe
• 3 switchable azimuth directions
• Very low-angle radiation
• Deep rear nulls when phasing is optimized

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Height Analysis

The towers are approximately:

100 feet = 30.5 m
At 1.83 MHz:
λ ≈ 538 feet

Tower height:
100 / 538 = 0.186 λ

or about
67° electrical height

This is extremely useful for 160 meters.

A 0.18λ vertical is substantially better than the typical:

• 43-foot vertical
• Inverted-L
• T-loaded vertical

The towers are tall enough to produce good low-angle radiation while remaining practical.

-------------------------------

Likely Gain

Based on the reports and geometry, I would estimate:

Parameter	Estimate
Forward gain	3–5 dB over single vertical
F/B ratio	10–20 dB
Elevation peak	18–25°
DX takeoff angle	Excellent
Ground-wave performance	Good

-------------------------------

Overall Evaluation

For a practical amateur 160-meter directional system, I would rate this array:

8.5 to 9 out of 10

Strengths:

✓ Full-size 100-foot vertical elements
✓ Three switchable azimuth directions
✓ Proven RBN performance
✓ Excellent low-angle radiation
✓ Compact footprint compared with a four-square
✓ Easier phasing than a four-square

Potential improvements:

• Measure actual front-to-back using simultaneous RBN comparisons.
• Optimize phasing line lengths for deeper nulls.
• Add a fourth tower and convert to a four-square if maximum gain is desired.
• Use a receive-only phased array (Beverage, K9AY, or Flag) to complement the transmit system.

My conclusion is that the RBN data supports the idea that this is a well-functioning 3-element directional vertical array, not merely three towers fed in parallel. The phasing network appears to be successfully steering the main lobe among the NE, SE, and W sectors, and the evening RBN results from Southern California are consistent with a very respectable 160-meter DX antenna.

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As you can see the antenna evaluation was quite thorough.
The graphic I sent to Ashley made all the difference.

Have you ever thought about getting an evaluation of YOUR antenna system?