Roy W7YRV/SK developed the X Rhombic
- skylarkcolo
- Apr 23, 2024
- 7 min read
Updated: 9 hours ago
From Roy's web site
The late Roy Callison of Bisbee, AZ, ham call W7YRV/SK had nine X Rhombics arrays, which he developed, 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.
K0UO's Curtain Array with Distributed-fed is using the W7YRV "X" rhombics design and parts. It is a traveling wave antenna, which is a non resonant traveling wane antenna. The rhombic antenna can radiate at elevation angles close to the horizon, and is called a Traveling wave or a Leaky-Wave Antenna (rhombics are fast wave), with a phase velocity greater than the speed of light. This type of RF wave radiates continuously along its length, and hence the propagation wave=number kz is complex, consisting of both a phase and an attenuation constant. A highly directive beams at an arbitrary specified angle can be achieved with this type of antenna, with a low side-lobe levels. The phase constant of the wave controls the beam angle (and this can be varied changing the frequency, while the attenuation constant α controls the beamwidth. The aperture distribution can also be easily tapered to control the side-lobe level or beam shape. Leaky-wave antennas can be divided into two important categories, uniform and periodic, depending on the type of guiding wire cable structure.
Nine rhombics antennas (reconfigured)
Three 1100 foot long rhombics 120' high and the control relays giving you six direction. I used these antennas for about 18 months until I figured out how to put 9 of them on my 40 acres. This were the largest antenna since W6AM had is farm, from the late 1940s through the 1980s.
Roy said: "This is the relay control box that takes the power to one end of the rhombic antenna and then brings back the reflected power to the shack to be terminated making the antenna transmit only in one direction. The four deck wafer switch allows me to select any of the six directions". K0UO has this control box and it is in use at K0UO today on the phased X-Rhombic Curtain
Nine rhombics antennas reconfigured. You cut a diamond shaped rhombic in half, and then put it back together in the form of an X, and feed it in the center, now you have electrically the same antenna. These rotating rhombics change directions in 20 degree steps, and they cover all bands from 160 through 10 meters. The apex angle can be adjusted from 40 degrees on the high bands to 120 degrees for the low band. Of all the antennas I have built, this was the best all around antenna. If I had to do it over again, I would have made them 120 feet high to get a little lower angle of radiation, but at 65 feet it was a super great performer. When I started building 197 foot towers for the 80 meter sterba curtains, the center tower of this antenna system was in the way, so although it grieved me to remove it, I knew that if the 80-meter antenna system didn’t work out, it would be no big deal to rebuild it.
The 600-ohm transmission line goes to the relay control box that is connected directly to the antenna system.
Above, 120' feet of 3 inch pipe, to be a tower for the 20 meter sterba curtain. The 50 foot triangular tower section on the truck has the 120' tower wired to it, in order to keep the ends of the pipe off the ground.
The reconfigured rhombic antenna system with the transmission lines coming down to ground level. Ever thing worked very well, so later we moved the relay box to the top of the tower
Below,This is a 40' gin pole pulling up a 65' rhombic tower.
BELOW:
Roy Said:
"This is a Gila monster that I almost stepped on. I heard a loud hiss, and I jumped a few feet, at first; I thought it was a rattlesnake. I just had to get a picture of him, because you almost never see one in the daytime".
It, looks complicated but its not, each deck is for a different apex.
Below, This is the relay switching box at the base of the tower
The transmission lines coming down to the relay box. The antennas performed great with the relay box at ground level, a look inside the relay box. The wires seem to be going everywhere. You might think you could have an impedance problem, but it was not apparent.
"Don't underestimate the performance of the Rhombic, unless you've 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."
SEE ROY's BLOG https://w7yrv.blogspot.com/
USSR
Grigory Zakharovich Ayzenberg (Григорий Захарович Айзенберг, 1904–1994) was a monumental figure in Soviet radio physics and the chief architect behind the USSR’s global shortwave and military antenna infrastructure.
The Prolific Author: He held 53 Soviet author certificates (patents) and published over 60 core scientific works. His definitive textbook series, including "Shortwave Antennas" (Коротковолновые антенны) and "Ultra-Shortwave Antennas" (Антенны ультракоротких волн), became the definitive guides for Soviet communications engineers.
Mastering Traveling-Wave Antennas: While Western designers concentrated on resonant aluminum beams (such as Yagis), Ayzenberg excelled in wire arrays utilizing traveling waves (Rhombics, V-Beams, and Fishbone arrays). He developed the shift from single-wire systems to multi-wire "curtain" configurations to reduce high-impedance loads, stabilize SWR, and expand operating bandwidths.
1. The Core Architecture: Cross-Phased Geometry
A standard planar rhombic consists of two V-shaped long-wire antennas connected end-to-end to form a single flat diamond. The X-Rhombic fundamentally shifts the wire layout:
Instead of running parallel or flat, the elements are deliberately crossed or split into an X-configuration at the side apices, or the array features two interconnected, overlapping rhombic structures driven by a unified feeding network.
The structure effectively forms a multi-tier or intersecting spatial loop. By doing this, the RF current does not just transition linearly down a simple diamond; it undergoes an instantaneous spatial phase adjustment mid-flight down the array's length.
2. Eliminating the "Height-to-Wavelength" Trap
The fatal flaw of any standard horizontal rhombic is that its vertical takeoff angle (elevation angle) is rigidly bound to its physical height above the ground plane ($h/\lambda$).
If the ionosphere shifts (e.g., from day to night) and requires a significantly lower or higher takeoff angle to sustain the circuit, a standard flat rhombic's gain plummets because its physical height cannot change.
The Soviet Solution: The X-Rhombic introduced a form of vertical taper or spatial diversity. Because sections of the "X" configuration occupied different vertical planes or variable sloping angles relative to the ground, the antenna naturally generated a composite wave that desensitized the array to strict ground-reflection height constraints. This gave the Soviet military and international broadcast networks a stable, low takeoff angle across a vastly wider frequency matrix without moving the physical masts.
3. Radical Sidelobe Damping
When driving hundreds of kilowatts into a long-wire array, parasitic sidelobes waste massive amounts of power and cause destructive intercept vulnerabilities.
Ayzenberg mathematically calculated that by crossing the wire paths in an "X" configuration, the radiation fields of the unwanted minor side-lobes generated by the front half of the antenna were precisely $180^\circ$ out of phase with the sidelobes generated by the rear half.
This caused destructive phase cancellation for almost all off-axis radiation. The resulting main forward beam was incredibly pure, dramatically increasing the front-to-side and front-to-back ratios compared to a standard Bruce rhombic.
4. Maximizing Tower Efficiency (The Economy of Scale)
In the punishing Soviet interior, erecting heavy, guyed steel masts was a massive logistical and financial strain. Engineers could not easily afford to build a brand new 4-tower footprint for every single target frequency or direction.
The X-Rhombic geometry allowed for interlacing and stacking. Engineers could suspend an X-shaped configuration within the exact same physical footprint of an existing array, utilizing the same side masts.
By feeding the X-array in parallel or implementing a branched delay network, a single installation could perform the work of multiple independent antennas. This configuration allowed the USSR to maintain highly directional, high-gain links to distant targets like Cuba, North America, and Southeast Asia using a heavily optimized footprint.
Roy's Blog, 2 comments:
K0UOJune 25, 2018 at 10:17 AM I talked to you a few years ago after I got my rhombic system working here in Kansas I really appreciate design information you have on the your old system. I especially like the feeding from the center X design rhombic I wished I could have thought of that before I installed these three big ones here in Kansas that I have. Reply
K0UOApril 30, 2019 at 6:44 PM I JUST WANTED TO SAY, THANK YOU ROY. After meeting you in Jan 2019, I have been able to use your X Rhombic design to build a Distributed-fed Curtain by stacking two X-Rhombics at 190 foot, and 100 foot ,and it is a steerable design. The antenna is also using Roy's old outside control-box (rebuilt) that you see in this blog. Reply. W7YRV lives on, at the K0UO large antenna farm.
SEE THE "X RHOMBIC" USED AS A CURTAIN ARRAY 20db on 40 meters
SEE K0UO's CURTAIN PAGE https://www.k0uo.com/post/current-distributed-feed-system-as-used-on-sterba-curtains-will-be-utilized-on-the-new-antenna
SEE ALL BLOGS Here, & Just Skip the first few pages, and go to the Blog List
I guess you can say go big or go home after looking at all this.
There'll be a time when the military wish they hadn't took all their big antenna Farms down