Math for the Rhombic & V Beams Array

Name: The KØUO Rhombic Antenna Farm and Antenna Test Range
Address: 4KS Walz airport
Location: 1200 acre antenna farm

skylarkcolo
Apr 23, 2024
5 min read

Updated: May 7

https://www.k0uo.com/post/rhombic-math-design

a view of a chart with frequency data for a rhombic antenna layout, design and building, USED BY k0uo AT THE WORLDS LARGEST hf ANTENNA FARM. Rows and columns are color-coded. Includes a diagram and text about gain and direction. used at General Steven Walz's, known as K0UO 1200 acre antenna farm, The number one in the world Amateur radio “Super Station” which is the worlds largest antenna site and test range with super ham station, k0uo ham radio station k0uo,
miles of antennas for ham radio
dozens of tall antenna support structures, — Chart detailing rhombic antenna specifications and measurements, including frequency ranges and dimensional values for both un-terminated and terminated configurations, with adaptable frequency settings for user customization.

The above is all the info/data that you need to build a Rhombic

The site emphasizes the scientific method: model → build → far-field test → refine

showing a Graph labeled "Design Chart for Constructing Rhombic Antennas for Maximum Output," showing curves and gridlines. Text at bottom reads "Figure 190."USED BY k0uo AT THE WORLDS LARGEST hf ANTENNA FARM — Design chart illustrating the relationship between wave angle, height, and tilt angle for optimizing the construction of rhombic antennas for maximum output.

Diagram illustrating wave propagation with angles and points labeled. Includes terms like wave direction and ground. Caption: Fig. 1—Horizontal rhombic antenna dimensions.
K0UO using this for the install of his large antennas — **Diagram illustrating the dimensions and phase angles of a horizontal rhombic antenna relative to wave direction and ground reflection.**

NOTE, Don't underestimate the performance of the Rhombic, unless you have personally built and used one. Because of their excessive size (area) covering many acres, you see their real advantage of thousands of feet of wire in the air, which creates receive signal diversity, by capturing signals at different times and different angles, vastly eliminating fading QSB, and firing out the transmitted RF in the same way. Traveling wave antennas are very unique and unlike many other antenna in common use, and modeling will not show this major advantage.

The site emphasizes the scientific method: model → build → far-field test → refine

I now use NEC5 (newer MOM algorithm) from Lawerence Livermore Lab, but it still won't show the real performance of the Rhombic

A word about modeling: You no longer need the latest modeling software, as it's design is rapidly evolving with Artificial Intelligence.

We started integrating AI with modeling in 2024, and now have developed an AI analysis platform focused on antenna performance and specific parameters. Be cautious and invest time in setting the correct parameters for your "AI platform".

A word about modeling: You no longer need the latest modeling software, as it's design is rapidly evolving with Artificial Intelligence.

One high end paid AI platform is now using AN-SOF, which is a robust simulation engine designed for the modeling and analysis of complex antenna systems and radiating structures.

Gain total spatial awareness of your antenna’s performance with immersive 3D rendering. AN-3D Pattern utilizes colored mesh and surface mapping to visualize radiation lobes with professional clarity.

Creating a well-designed platform using scientific and engineering knowledge is crucial.

Relying solely on ChatGPT is not the solution at all!

K0UO & RSI Corp, which employs Artificial Intelligence for designing traveling wave and other antennas, is significantly more reliable and completes the process in just 5% of the time needed by traditional modeling programs. While setting it up requires time, akin to the initial setup of the original computer modeling software, it's crucial to remember that assuming artificial intelligence operates flawlessly can lead to mistakes.

After designing, we confidently utilize our outdoor testing range to validate the results. Confirming results and assessing performance in real-world conditions is essential. Over the years, my team has effectively collaborated with numerous commercial clients to achieve this.

I started with calculators, and some of us are old enough to remember using slide rules and pencils, before moving to computer modeling. It's astonishing to see how far we've come, and in a few more years, like it or not AI will further revolutionize antenna design.

L. B. Cebik, W4RNL Model below

Diagram of V- beam array antenna patterns at 3.5 MHz. Shows two patterns: unterminated and terminated, with concentric circles and lines. USED BY k0uo AT THE WORLDS LARGEST hf ANTENNA FARM — **These are for 80 meters and need to be one half wave high to control ground loss**

Diagram showing rhombic antenna patterns at 3.5 MHz. Two azimuth patterns labeled Un-terminated and Terminated are compared below. USED BY k0uo AT THE WORLDS LARGEST hf ANTENNA FARM — **Azimuth Patterns of Rhombic Antennas, for both** **Un-terminated and Terminated**

Table compares performance of 3.5-MHz arrays: gain, angle, front-back ratio, beamwidth for single long-wire, V, and Rhombic arrays, both terminated and unterminated. USED BY k0uo AT THE WORLDS LARGEST hf ANTENNA FARM — Performance comparison of 3.5-MHz long-wire arrays: The table showcases gain, take-off angle, front-back ratio, and beamwidth for single long-wire, V, and rhombic array types, comparing unterminated and terminated states. Notably, the rhombic terminated type offers the highest gain and front-back ratio.

More into at https://antenna2.github.io/cebik/content/ao/ao11.html

WA7ARK recommends NEC5 (newer MOM algorithm) from Lawerence Livermore Labs greatly adds to modeling capability (adds buried conductors) and makes it much easier to write models (many less restrictions compared to NEC2d)

I now model all my antennas using NEC5 and HFTA (High Frequency Terrain Analysis) to evaluate the take of angle of the various antennas over real ground, and use 3/8" Triple Galvanized Wire Rope Cable is used for the antenna wire.

Also at the K0UO rhombic farm and antenna test range, the world’s largest facility dedicated to advanced antenna design and testing, engineers push the boundaries of what’s possible. We don’t just guess antenna gain - we measure it meticulously, ensuring every antenna performs at its peak.

Today, nearly all HF amateur radio Yagi beam antennas, along with numerous commercial HF beams, remain unevaluated on antenna far-field test ranges. While VHF and higher frequency band antennas have undergone informal testing by organizations like The Central States VHF Society and Microwave Update, exposing deficiencies in some manufacturers' models and claims, there is a notable lack of real-world far-field testing for HF antennas, including wire-based and high-performance Yagi beams. Manufacturer documentation often misleads consumers.

a view of The KØUO Rhombic Antenna Farm and Antenna Test Range: Home to the World's Largest amateur radio (ham), High Frequency (HF) Wire Arrays, miles of wire in the air and on the air daily, engineered using AI and cutting edge technology, designed by General Steven Walz — One of the K0UO's Rhombic fed point and view of the other supports poles

NOTE: Do not underestimate the performance of the Rhombic unless you have personally built and used one. Despite their large size, covering many acres, their real advantage lies in having thousands of feet of wire in the air. This setup creates receive signal diversity by capturing signals at different times and angles, significantly reducing fading QSB and efficiently transmitting RF. Traveling wave antennas are unique and unlike many other commonly used antennas, and modeling does not reveal this significant advantage.

Based on the site other blogs content, our four 40‑meter resonant rhombic antennas at K0UO are aimed at the primary DX directions as part of the farm’s 14‑direction coverage (arrays and V‑beams every ~25°). The blog posts and site notes identify collective coverage rather than a numbered compass heading for each rhombic, but they state the system was laid out to target the eight main DX areas and that the full farm (four rhombics + three V‑beams) provides beams every ~25°. Specifics given in the material: the arrays serve NE/Europe, Africa/Mideast, Central & South America, Oceania/Asia and other DX sectors; one vertical‑polarized 1/2 rhombic is noted as firing to Central & South America.

The K0UO amateur ham radio antenna range, and testing site has the use of over a 1200 acres around the main antennas for far field measurements, using a portable tower or drone loaded with calibrated RF EME survey instruments (used for DOD/ Govt, Commercial and amateur radio), see the far field test page. https://www.k0uo.com/post/model-and-then-do-far-field-test

The K0UO antenna test range site makes use of the 4KS Walz airport and its surrounding area as a practical learning environment for STEM (Scientific, Technical, Engineering, & Mathematics) antenna projects in a real-world outdoor setting. If your group has a university aerospace or antenna research STEM program, please let me know. The KØUO Rhombic Antenna Farm and Antenna Test Range: Home to the World's Largest amateur radio (ham), High Frequency (HF) Wire Arrays, miles of wire in the air and on the air daily.