High gain HF Rhombics bets Yagi Beams
- skylarkcolo
- Mar 3, 2024
- 15 min read
Updated: 2 days ago
I once overheard a conversation between Don Wallace W6AM and a neighbor discussing their antennas on the 20-meter band. Don was using one of his rhombics directed towards Europe, while his neighbor had a 5-element mono-band yagi mounted at 150 feet. As they compared their antennas, they received signal reports from numerous European stations. Don's rhombic consistently outperformed, being at least 20dB stronger than his neighbor's 5-element yagi at 150 feet.
When discussing antenna performance, the practical application of these theories is crucial. For example, a Rhombic antenna, recognized for its distinctive shape and high gain features, can greatly improve the quality of transmitted and received signals. This antenna is especially useful for long-distance communication because of its directional properties. It can effectively manage the bandwidth of communication, enabling operators to access frequencies that might otherwise be obscured by noise.
The Rhombic antenna's design consists of two pairs of wires that form a diamond shape, which contributes to its ability to focus energy in a specific direction. This focus not only improves signal strength but also enhances the clarity of the communication, making it a favored choice among seasoned operators who are serious about their craft. The ability of a Rhombic antenna to perform excellently in various conditions, despite what theoretical models may suggest, exemplifies the importance of practical experience and on-the-air testing.
Moreover, the performance of such antennas can be influenced by various factors including terrain, atmospheric conditions, and even the specific equipment used in conjunction with them. This is where the distinction becomes clear between those who rely solely on theoretical models and those who engage in hands-on experimentation and adjustment. The big guns, who often have the experience and knowledge to tweak their setups, can achieve remarkable results that far exceed the predictions made by software like EZNEC.
The Big Advantage, all long Traveling wave antennas are known for fantastic Improvements in the reduction of QSB fading, for both transmit or receive.
It is like Diversity, theses large arrays cover a lot of area. My station uses over a mile of wire, so you are both listening and transmitting signals coming and going at different angles. Signal-to-noise ratio (S+N/N ratio, or SNR) is one technical aspect not too many amateurs give a second thought about, however if you can't hear them you can't work them. This is very apparent on audio reception,long Traveling wave antennas eliminates much of the audio amplitude fading for both transmit or receive. The RF signal is almost never in a stable phase relationship at both places at the same time. This means the signal will have random phase and amplitude differences. The arrival angle and polarization of incoming signals will change. This generally results in the fading, by having many wavelengths of wire in the air, the chances are that while one experiences a fade, the other will not. The power is in the diversity size of the array and what you can now hear with out QSB fading. Traveling wave antennas are just quieter and have substantial noise reduction. That is why so many people use the Beverage receive antennas.
The K0UO site, uses proudly uses repurposed equipment from W6AM's old station, W7YRV, Voice of America, The BBC and other legendary stations on the K0UO large arrays.
Comparing Rhombic Antennas to Other HF Antennas
| Antenna Type | Gain | Bandwidth | Size | Directionality | Cost |
|--------------------|---------------|-----------------|---------------|-----------------|----------------|
| Rhombic | High (12-18 dB) | Wide (3-30 MHz) | Large | Highly directional | Low |
| Dipole | Standard (2-3 dBi) | Narrow | Small | Omnidirectional | Very low |
| Yagi-Uda | Moderate (6-10 dBi) | Narrow | Medium | Directional | Moderate |
| Log-Periodic | Moderate (6-10 dBi) | Wide | Medium | Directional | Moderate |
Rhombic antennas offer higher gain and wider bandwidth than many common HF antennas but require more space. Yagi antennas provide good gain with smaller size but cover a much narrower frequency ranges. Dipoles are simple and small but lack directionality and gain.
Understanding Rhombic Antennas and Their Functionality
Rhombic antennas are a fascinating type of antenna that belong to a broader category known traveling wave arrays
.
The performance of such antennas can be influenced by a multitude of factors that extend beyond mere theoretical calculations. These factors include, but are not limited to, the geographical terrain surrounding the antenna, atmospheric conditions such as humidity, temperature, and pressure, and even the specific equipment used in conjunction with the antennas themselves. For instance, the presence of mountains, tall buildings, or other obstructions can significantly affect signal propagation and reception, leading to variations in performance that are not always accounted for in theoretical models. Additionally, atmospheric phenomena, such as temperature inversions or varying humidity levels, can cause fluctuations in signal strength and clarity, further complicating the predictive accuracy of software simulations.
This is where the distinction becomes particularly clear between those who rely solely on theoretical models and those who actively engage in hands-on experimentation and adjustment. Theoretical models, while valuable for initial designs and predictions, often cannot capture the full complexity of real-world conditions. In contrast, practitioners who take the time to experiment with their setups, making adjustments based on live feedback from their antennas, can often discover optimal configurations that significantly enhance performance. The big guns in the field—those seasoned professionals and dedicated amateurs—who possess the experience and extensive knowledge required to fine-tune their setups, can achieve remarkable results that far exceed the predictions made by software like EZNEC.
These individuals often utilize a combination of empirical testing and a deep understanding of radio wave propagation principles, allowing them to manipulate variables such as antenna height, orientation, and even the choice of feedline to maximize their signal strength and clarity. They may also employ advanced techniques such as remote monitoring and data logging to assess performance over time and under varying conditions. This iterative process of testing, analyzing, and adjusting enables them to refine their setups continuously, leading to a level of performance that is not only practical but also often astonishingly effective. As a result, the gap between theoretical predictions and real-world performance can be bridged through diligent experimentation and a commitment to understanding the traveling wave antennas operation.
These antennas are specifically designed to efficiently radiate or receive radio waves, and they exhibit unique characteristics that set them apart from other types of antennas.
The Rhombic Arrays can beat the massive stacked HF yagi beam arrays.
What is a Rhombic Antenna?
A rhombic antenna is typically constructed in the shape of a rhombus, which is a four-sided figure with equal-length sides. This geometric configuration is not merely aesthetic; it plays a crucial role in the antenna's operational efficiency. The design allows for a wide bandwidth and a relatively high gain, making rhombic antennas particularly effective for long-distance communication.
Traveling Wave Antennas Explained
The classification of rhombic antennas as traveling wave antennas indicates that they operate based on the principle of wave propagation along the antenna structure. Unlike standing wave antennas, which have fixed points of maximum and minimum voltage (standing waves), traveling wave antennas like the rhombic utilize the continuous movement of waves along the length of the antenna. This results in a more uniform radiation pattern and often leads to enhanced performance in terms of signal strength and clarity.
Operational Characteristics
One of the key operational characteristics of rhombic antennas is their ability to maintain a consistent radiation pattern over a wide frequency range. This is particularly advantageous in applications where frequency agility is required. Additionally, rhombic antennas can be designed to operate in various configurations, allowing them to be tailored for specific communication needs. Moreover, the placement and orientation of a rhombic antenna can significantly influence its performance. Typically, these antennas are installed at a height that optimizes their line-of-sight communication capabilities. The angle at which the antenna is deployed can also affect its gain and directivity, making it essential for operators to consider these factors during installation.
Applications of Rhombic Antennas
Rhombic antennas are widely used in various applications, particularly in the field of amateur radio, military communications, and broadcasting. Their ability to cover large distances makes them suitable for long-range communication systems. Furthermore, due to their relatively simple construction and low cost, they are often favored by hobbyists and researchers who require effective communication solutions without significant financial investment. In summary, rhombic antennas are a specialized type of traveling wave antenna that leverage their unique geometric design and operational principles to facilitate efficient communication over long distances. Their versatility, operational characteristics, and wide range of applications make them an important component in the field of radio telecommunications. Understanding the intricacies of how these antennas function can greatly enhance the effectiveness of communication systems that rely on them.
In conclusion, while theoretical models provide a useful framework for understanding antenna performance, it is the real-world application and the ability to adapt to changing conditions that truly defines success in the field of radio communications. A Rhombic antenna serves as a prime example of how practical experience and a willingness to experiment can lead to superior performance, showcasing the difference between the big guns and the little pistols in the world of amateur radio.
A Rhombic Antenna = The highest development of a long-wire antenna.
Each antenna a K0UO was built for 40 meters and above, with over 600 to 700 foot per-leg and +1200' end to end, 6 to 7 Acres each on 80 to 100 foot wood poles. My four antennas each cover an area equal to five football fields. The Front to Back is like a brick wall, maybe +40dB or more. That makes them 4 to 6 Wave-Lengths long on each of the four sides, or 16 to 24 wave-lengths total for 40 meters, these may be the largest 40 meter Rhombic antennas in current amateur use. K3LR may or may not have more gain with beams, using 4 over 4 over 4 on 40 meters, but he needs to rotate. The Re-entrant Rhombic array is one of the highest forward gain HF antennas with its 90% efficiency, now with very high gain, and low noise receive characteristics.The Rhombic Arrays have much more gain than the massive stacked HF yagi beam arrays, that I had up previously.
Dick AD4U from eham.net
On the W8IJ antenna page, he presents intriguing observations regarding the modeling of the large rhombic antenna. It's important to note that he isn't particularly enthusiastic about its advantages or gain per area of antenna space used. He mentions, "The rhombic's performance is largely limited by the high levels of spurious lobes and its poor efficiency (50%), particularly over typical soil. The standard rhombic ranks among the lowest in terms of gain-per-acre for high gain HF antenna arrays."
However, I now utilize a Re-entrant system that achieves 90% efficiency, by re-phasing the power back into the antenna, rather than dissipating it as heat in termination resistors.
Therefore, don't underestimate the performance of the Rhombic unless you've personally built and used one.
Keep in mind that I'm comparing my rhombics to large stacked single band beams that I previously used on 195-foot towers.
It can be truthfully said, that "a Rhombic antenna occupies more space per dB of gain than any other antenna." This statement holds significant weight in the realm of antenna design and application, particularly when discussing the trade-offs between gain and physical footprint. The Rhombic antenna is renowned for its very high-gain characteristics, making it a preferred choice for many long-distance communication applications. However, one of the major drawbacks is its requirement for extensive land area, often measured in acres, which can be a limiting factor for many operators. Furthermore, when properly terminated, the efficiency of a standard Rhombic antenna is only about 50%. This means that nearly half of the power fed into the antenna is dissipated rather than radiated effectively, which is a critical consideration for maximizing the performance of a communication system. An alternative impedance-termination system that has been explored, albeit primarily in a limited number of large broadcast stations where input powers exceed 50 kW, is known as the re-entrant line termination. This innovative approach was notably developed by Clyde Haehnlen SK, who crafted the specifications for the Voice of America antenna system located at the Bethany, OH Relay Station. The re-entrant Rhombic antenna designed for this application achieved an impressive efficiency of 90%. This was accomplished by re-phasing the power rather than relying on the conventional method of dissipating excess energy through heating termination resistors. In this advanced system, the Rhombic antenna is terminated in a transmission line, which is then coupled back to the input through appropriately designed voltage-matching and phasing networks. This clever arrangement allows for the energy that would typically be lost in the dissipation line to be fed back into the antenna, resulting in significantly less than 50 percent of the energy being wasted. The old VOA Bethany site in Ohio exemplified this efficiency, achieving levels exceeding 90%. The design effectively feeds back the wasted RF energy "In-Phase," directing it back into the feeder end of the antenna. This feedback mechanism is crucial for maintaining optimal performance, particularly in scenarios where there are variations from the stubs' frequency. In such cases, it is essential that the stub is returned to ensure that the system remains balanced and efficient.
K0UO uses Re-entrant Rhombic array is one of the highest forward gain HF antennas with its 90% efficiency,one of the highest forward gain of any HF ham antenna.
I am now the only station using re-entrant line termination equipment, which is re-phasing the power instead of heating up termination resistors. These antennas are now recognized as the largest wire antennas in the world. This unique position allows me to leverage the advanced design principles pioneered by Clyde Haehnlen, which have proven to be invaluable in maximizing the efficiency and effectiveness of my transmission capabilities. The implementation of this re-entrant line termination technology not only enhances the performance of my antennas but also sets a new standard in the field of antenna design and broadcasting.
Clyde provided me with invaluable design information for re-phasing a few years ago before his passing. His insights into the intricacies of antenna design and efficiency optimization continue to influence my work and inspire new innovations in the field. The legacy of his contributions lives on through the advancements made in antenna technology, particularly in the realm of high-efficiency systems like the one I am currently operating. As I continue to explore and expand upon these ideas, I remain committed to pushing the boundaries of what is possible in antenna design and communication technology.
A rhombic antenna offers the unique benefit of operating across very wide frequency ranges with consistent SWR and high gain, which a basic mono-band yagi cannot achieve. The rhombic is also a straightforward antenna, needing only four supports (three supports for the Vee beam and one support for inverted Vee variations). My antennas use 3/8" Triple Galvanized Wire Rope Cable used for the antenna wire.
The Rhombic arrays features can be highly advantageous for everyday use in amateur radio service, as amateurs are not point-to-point shortwave broadcasters, military, HF Stock Traders, or wire news services. Amateurs simply want to make QSOs! Additionally, most amateur radio operators don't have the budget for expensive tall towers and stacked mono-band beams, nor the capability to climb and maintain such structures.
Others that are using the King of antennas, In the late 1940s to 1970s W6AM had many 1000 footers and one was 1500 ft (in fact the main E/W is using parts from W6AM's farm). TF4M put up a larger one at one time, and Roy W7YRV/SK had nine at one time and he developed the X Rhombic, which he had one for every 20 degrees. That was a truly remarkable accomplishment for an amateur station (You must see his page, great info w7yrv.blogspot.com/2013/). It was an extreme pleasure for K0UO to meet Roy, even in his 90's, he was still an encyclopedia of knowledge when it comes to very high gain antennas. K0UO is very privileged that W7YRV has entrusted him with the schematics, drawing, and photos of these fabulous antennas. W1VDE Roger in OR has six and is on the air daily, also VK3MO, ZL6QH, and in Texas N5APR and W5BY Jeff, had a few at their ranch's, KL7KK in AK has one along with a few VK's, and V55V (V55W) in Namibia had 2, but they are now down.
VK3MO Ian also has a stacked rhombic antenna with 8 wavelengths on a leg giving a total of 1340m of radiating wire. The upper rhombic is at 40M and the lower rhombic is at 21M. The rhombic had a gain of 23dBi at a take off angle of 5 degrees on 20M and is directed at New York. The rhombic was modeled using EZNEC and it has 3dB more gain than the 5/5/5/5 yagis. Both the yagis and the rhombic have a take off angle of 5 degrees which allows a comparison between the two antennas in the direction of New York. Ian sees see the 3 dB advantage which validates the accuracy using NEC antenna modelling software.
Rhombic antennas were the ultimate antenna design back in the Golden Age of Wireless. However, building one required a large tract of land and a number of tall telephone poles, because they have dimensions several times the wavelength. To most amateurs the positive thing is there are no large mono-band antennas to maintain, or rotators to fix, and rhombics allows for instantaneous direction and band switching. They normally can be installed at very low cost, if you have trees to hang them from, all that is needed is a lot of wire and time! Also the key concept with traveling-wave antennas is that there are no standing waves, which means that the current and voltage levels are the same everywhere along the antenna conductors. So the rhombic antenna does have the very distinct advantage of working over very wide frequency ranges with flat SWR and high gain.
Advantages
The structure of the antenna is quite simple and it is cost affordable.
It provides high directivity by radiating most of the power along the main axis.
It provides efficient long-distance radio communication when installed in a large space.
The offered input impedance is quite large.
The radiation pattern and input impedance remain constant for a large range of frequency.
These can be easily switched from one working frequency to another during operation.
It suits long-distance F-layer propagation due to low vertical radiation angle.
A excellent choice HF antenna for commercial, maritime shore stations, military, broadcasting, frequency agile, requirements, high speed traders, diplomatic, EME and ham amateur radio.
Re-entrant Rhombic array is one of the highest forward gain HF antennas. with its 90% efficiency
Paul Bittner, WØAIH/SK, had a four rhombic contest station
SEE @
W0AIH, How did his smaller rhombics Play?
A detailed modeling analysis of these
rhombics is beyond the scope of this ar-
ticle, but Paul did have Lew, K4VX, model
these antennas using Paul’s dimensions
at a height of 60 feet. He found that with
a length of 495 feet, a width of 206.7 feet
and a half-apex angle of 22.7°, the gain
at 14.2 MHz is 18.9 dB. At 21.2 MHz, the
gain is 20.8 dB. In an actual application, it
is suggested that the theoretical gain would
be reduced by approximately 2 dB to ac-
count for losses in the termination resistors.
Lew also found that the presence of tow-
ers inside a rhombic does not have a sig-
nificant effect on the antennas’ perfor-
mance. Of course, it’s one thing to model
an antenna and another to use these
rhombics at the farm in real-world contest-
ing situations. The anecdotal evidence is
quite positive.
Scott, NE9U, recalls being in the 20
meter shack at 4 AM and finding the band
dead. He was twirling the stack (4/4/4/4
Hy-Gain 204Bs at 50 to 199 feet) and didn’t
hear a thing. Just for the heck of it, Scott
switched to the European rhombic and, lo
and behold, he heard an HZ (Saudi Ara-
bia)! It was the only signal on the band. He
moved the stack back to 43° and switched
to it. The Saudi station was gone! He
switched back to the European rhombic,
and there it was at S-9. Scott worked him
on the first call.
Bill, ACØW, has found that when the
band is just starting to open on the East
Coast and there’s still some time before it
opens in the Midwest, the rhombics allow
him to get on the band earlier. By getting
on the band as the same time as the East
Coast stations, he is able to establish and
hold a run frequency. If he waits until the
stack is able to hear and work stations,
the band is so crowded with East Coast
stations it’s very difficult to find an opening
and establish a run frequency.
Paul, WØAIH, has found that the African
rhombic plays very well into Oceania (VK/
ZL) when he reverses its direction. He
dreams of a 160 meter rhombic aimed at
Europe, but he also realizes that even his
120 acres do not provide enough room
to fit the necessary 2000 feet legs. On
160 meters Paul does sometimes listen
on the rhombics which are very quiet (his
transmitting antenna is a vertical array). He
simply switches to the rhombic that “hears”
the best; typically it’s the one pointed in
the direction of the station he’s working,
Paul says "My personal favorite is the JA rhombic
on 20 meters. I typically use the stack,
mentioned above, for most of the morning
and into mid-afternoon. The first time I hear
or work a station in Japan, however, I im-
mediately request the JA rhombic and start
calling “CQ.” Almost every time this leads
to a long and productive JA run".
TO SEE the complete Blog list check @ https://www.k0uo.com/k0uo
View of General Steven Walz 1200 acre world largest antenna site and test range, k0uo ham radio station k0uo,
miles of antennas for ham radio
dozens of tall antenna support structures, like FCC registered towers up to 195 foot, numerous 100 foot wood powerline poles, concrete silos, and portable mobile towers
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)
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 Test Range: Home to the World's Largest amateur radio (ham), High Frequency (HF) Wire Antennas.
The KØUO Rhombic Antenna Farm in Kansas, consisting of many acres, with "Miles of Wire in the Air & On the Air". Best known as an antenna Experimenter, Ragchewer 1st and DXer for fun! "It takes years of Passion, Hard work, and Commitment to build a great station".
It is great that Steve has put all this info together