3 Types of Microwave Propagation and the Horn Antenna
- September 18, 2012
- Antenna diversity, Antennas, China Basin, Dick Laine, horn antenna, microwave, microwave propagation, Principal Engineer, Radio Head Technology Series, Radio Heads, Radiohead, San Francisco, Space Diversity
Horn antennas on the roof of a microwave relay station near Madison St. and 17th Ave, Capitol Hill, Seattle, Washington State, USA. (Photo credit: Vladimir Menkov via Wikipedia)
Between any two microwave radio antennas, there is one direct ray and multiple refractive/ reflective multi-path rays. In the eighth and last installment of our Radio Head Technology Series, Aviat Networks Principal Engineer and master storyteller, Dick Laine, relates how restrictive tower rules for San Francisco’s historic China Basin Building required fine adjustments of a horn antenna to resolve reflective rays from the surrounding bay.
As Dick tells it, to accommodate a Space Diversity arrangement, one horn antenna on the building had to be hung upside down. During the installation process, the alignment for the upside-down diversity antenna created a reflection point 3 miles out into the bay. Because of this installation, the performance was horrible, but at the time no one knew why. For example, when a little speedboat or anything larger went through the reflection point, there would be an outage as the signal was interrupted. There did not seem to be an obvious fix to the alignment issue. The horn antenna did not have a way to check the alignment on the horizontal with a bubble level.
To find out how Dick solved this antenna mystery, register for the Radio Head series (it’s free). Then to put it all in context, Dick goes over Huygens’ Principle as it applies to microwave signal diffraction. And if you ever wondered what happened to periscope antennas, Dick provides some key insight! Tune in to find out!
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Got Protection? Diversity Schemes and Other Methods
- August 14, 2012
- Constellation, Dick Laine, Diversity scheme, Eclipse, line-of-sight, LOS, MegaStar, microwave, Microwave transmission, Radio frequency, TR6500, WTM600
Dick Laine, longtime principal engineer for Aviat Networks, delivers one of his patented presentations on microwave networking during an installment of the video blog Radio Head Technology Series.
Microwave radios come and microwave radios go, but the sage advice of Aviat Networks Principal Engineer, Dick Laine, has no end-of-life. In our seventh installment of the very popular video blog Radio Head Technology Series Dick talks about the diversity of diversity schemes and other protection methods available to microwave networking engineers.
Using examples from the radio legacy of Aviat Networks (e.g., Constellation, MegaStar—you must remember these, it hasn’t been that long) and our current microwave networking solutions (e.g., Eclipse, TRuepoint 6500, WTM 6000) he expounds on the past, present and future of protection. From Angle Diversity (one of the earliest diversity schemes used in Line-of-Sight digital microwave) to Hybrid Diversity (HD) and Frequency Diversity (that need licensing waivers to be used in many applications) to comparisons of fiber-like protection methods, Dick covers it all. For example, did you know that a four-dish HD antenna arrangement offers little to no performance improvement over a three-dish HD configuration?
So with free registration to the video series you can have the benefit of all of Dick’s wisdom and nonpareil presentation style on Diversity. You get access to all the earlier videos, too. (Did we mention there are six previous episodes?) And the presentation slides. And the podcast. And all for FREE! Wow! If you don’t see a topic that you think needs to be covered, feel free to submit your suggestion into our inbox. Register today!
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Protection and Diversity: 100 Percent Uptime the Goal
- July 4, 2012
- Antenna diversity, Dick Laine, diversity arrangements, frequency diversity, Microwave transmission, protection schemes, Radio frequency, Radio Head, Radio Head Technology Series, Space Diversity, wireless
The BT Thornhill microwave radio tower above demonstrates a Space Diversity protection scheme with its parabolic antennas placed apart from one another (Photo credit: Peter Facey via Wikipedia)
Traffic disconnect is unacceptable for most microwave systems, especially for homeland security and utilities. But Aviat Networks Principal Engineer Dick Laine says that it is economically unviable to have a microwave radio system that provides absolutely 100 percent uptime to accommodate every possible traffic downtime scenario. He adds that towers, waveguides and all other hardware and infrastructure would have to be completely bulletproof. This is true of every telecommunication system.
However, with protection schemes and diversity arrangements in today’s wireless communication solutions, microwave transmission can get very close to mitigating against long-term traffic outages (i.e., > 10 CSES, consecutive severely errored seconds) and short-term traffic outages (i.e., < 10 CSES).
In pursuit of the 100 percent uptime goal, Dick goes over many of the strategies available in the newest video in the Radio Head Technology Series, for which there is complimentary registration. For example, there are many approaches to protection, including Hot Standby and Space Diversity. In particular, Dick points out Frequency Diversity has advantages over many protection schemes, but few outside the federal government are able to obtain the necessary waivers in order to use it. Hybrid Diversity uses both Space Diversity and Frequency Diversity to create a very strong protection solution. A case study outlining Hybrid Diversity is available.
Other concepts Dick covers in this fifth edition of Radio Heads includes error performance objectives, bit error rate, data throughput, errorless switching, equipment degradation, antenna misalignment, self-healing ring architecture and something called the “Chicken Little” alarm.
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What is More Susceptible to Rain Outage, Vertical or Horizontal Radio Signals?
- June 20, 2012
- antenna polarization, Crane, Dick Laine, horizontal polarization, International Telecommunication Union, ITU-R, Microwave transmission, Radio Head Technology Series, Radio Heads, Radiohead, Rain Fade, vertical polarization
The world is divided into separate International Telecommunication Union regions. In many regions of the world, ITU methods of calculating rain outage are most commonly used. In other regions, such as North America, the Crane model is used more often. (Image credit: Wikipedia)
Ever wonder which antenna polarization is more susceptible to rain outage? Vertical? Horizontal? Which should you use for very long hops?
What would you do besides add extra fade margin to mitigate rain outage? Design a shorter path or use a lower frequency band?
Aviat Networks’ microwave radio guru, Principal Engineer Dick Laine, tackles these tricky questions and others in the latest episode of our Radio Head Technology Series of videos.
Dick also talks about rain outage—as calculated by ITU using a simple scientific calculator, or computer programs (Starlink) that use the Crane model. He goes through an ITU-R availability calculation in one example, noting specifically about rain attenuation calculation above and below 30 degrees latitude. Dick then proceeds into a deep dive on calculating outage when you know the fade margin, followed by a discussion on the Crane rain attenuation model.
Aviat Networks invites our readers to register to be added to our Radio Heads distribution list to get notified of new Radio Head Technology Series releases and links to replays.
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Five-Nines Availability and RCA’s Top Secret Communication Project
- May 25, 2012
- 45-rpm, 78-rpm, 99.999 percent availability, 99.999% availability, Dick Laine, five-nines, Gramophone record, microwave link, Microwave transmission, Principal Engineer, Radio Head Video Technology Series, Radio Heads, Radiohead, RCA, wireless, wireless engineering
Five-nines (99.999 percent) availability is a concept that is familiar in wireless engineering. Dick Laine, principal engineer of Aviat Networks, compares five-nines availability to 78-rpm records in our most recent episode of the Radio Head Technology Series.
As he relates, even with scratches and pops, a 78-rpm record still is able to transfer aural information so that you can hear it, i.e., its availability is intact, as it does not drop performance. Scratches and pops only represent degradation in the quality of communication. But when the record is broken, an outage occurs—no record, no communication.
The same goes for wireless communication systems. If a microwave link drops 315 or fewer seconds of microwave communications per year (in increments of up to 10 seconds at a time), it is maintaining five-nines availability. The microwave link is offering 99.999 percent availability for wireless backhaul. Only if the microwave link is unavailable for more than 10 seconds has an outage occurred, for the purposes of determining if microwave communications traffic has been dropped.
Dick goes on to explain about what happened in 1949 when 78-rpm records were superseded by 45-rpm records. Dick got a sneak peek at the top-secret 45-rpm record project when he visited the legendary RCA facility in Camden, New Jersey, which played a crucial role in the development of the modern music, radio and television businesses. Unfortunately, unlike a five-nines microwave link, 78-rpm and 45-rpm records are mostly unavailable nowadays.
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3 Models for Microwave Link Error Performance? Laine Explains
- May 11, 2012
- Aviat Networks, bell system technical journal, Dick Laine, International Telecommunication Union, Internet Protocol, ITU-R, microwave, microwave link, microwave link design, microwave link error performance, Microwave transmission, Principal Engineer, Radio Head, Radio Head Video Technology Series, Radio Heads, Radiohead, reliability or error performance, Richard Laine, tdm, Time-division multiplexing, Vigants, wireless, wireless engineering
In the second episode of Aviat Networks’ Radio Head Technology Series, Principal Engineer Dick Laine explains ITU-R models for Fixed Wireless Systems.
As most radio engineers know, Vigants calculations, which are discussed in a broadly cited Bell System Technical Journal article, are widely used to determine reliability or error performance for microwave link design. In Video 2 of Aviat Networks’ popular Radio Head Technology Series, which is now available for viewing, Principal Engineer Dick Laine explains how he uses Vigants calculations in conjunction with the three completely separate ITU-R Fixed Wireless System (FWS) models for TDM.
Because of all these models, he likes to use Vigants calculations as a “sanity check” to see that he is close to the correct result for his path engineering plans. The free Aviat Networks’ Starlink wireless path engineering tool can be used to handle Vigants calculations for Aviat Networks’ and other vendors’ equipment.
Can’t wait to hear more of Dick’s experienced views on microwave radio transmission engineering? You can get ahead of the learning curve by registering for the series and get these videos sent to your inbox as soon as they are released.
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Dick Laine’s 4 Keys to Successful Transmission Engineering of Microwave Links
- April 20, 2012
- Aviat Networks, Dick Laine, Farinon, Harris MCD, microwave, microwave engineer, microwave link, microwave link design, Microwave transmission, network engineering support, Principal Engineer, Radio Head, Radiohead, Richard Laine, Telecommunication, transmission engineering, wireless, wireless engineering
Dick Laine, Principal Engineer, Aviat Networks
Transmission engineering of a microwave link requires creativity and skill. So if you are looking for inspiration as well as high-quality wireless engineering instruction look no further than the “Radio Head Technology Series.” Radio Heads is a collection of videos and podcasts featuring our very own Dick Laine. Dick is arguably the most experienced microwave engineer in the wireless communication business, having spent more than 50 years working with microwave radio from its inception—here at Aviat Networks and our predecessor companies (e.g., Farinon, Harris MCD).
Dick has been involved with nearly every aspect of RF transmission, microwave link and network transmission design, and the effects of geoclimatic conditions on transmission of voice and now IP radio data packets.
In his own unique style, Dick has been teaching basic and advanced concepts for digital microwave transmission in seminars and training classes worldwide. Students who have taken his classes return years later eager to get a refresher from Dick and to hear about some of his great adventures in Asia, the Middle East, Africa and in the Americas.
In the first Radio Heads video titled “Check List for a Successful Microwave Link,” Dick explains the four key objectives or requirements for a well-done microwave link design along with “check list” items that the project manager or transmission engineer evaluates for proper design and deployment of a digital microwave link. If you have not already signed up for this video series, register to view the content.
If you find this video of value, please pass along the information to your friends and colleagues via Facebook, Twitter, LinkedIn or your other favorite social media network.
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4 Realities about Rain Fading in Microwave Networks
- August 23, 2011
- Aviat Networks, backhaul, Dick Laine, Frequency range, Internet Protocol, microwave, Microwave transmission, Principal Engineer, Rain Attenuation, Rain Fade, Rain Fading, Telecommunication, Time-division multiplexing, wireless
Rain fading (also referred to as rain attenuation) at the higher microwave frequencies (“millimeter wave” bands) has been under study for more than 60 years. Much is known about the qualitative aspects, but the problems faced by microwave transmission engineers—who must make quantitative estimates of the probability distribution of the rainfall attenuation for a given frequency band as a function of path length and geographic area—remains a most interesting challenge, albeit now greatly assisted by computer rain models.
A surprising piece of the puzzle is that the total annual rainfall in an area has almost no correlation to the rain attenuation for that area. A day with one inch of rainfall may have a path outage due to a short period of extremely high localized rain cell intensity, while another day of rain may experience little or no path attenuation because rain is spread over a long period of time, or the high intensity rain cell could miss the microwave hop completely.
Over the years, we have learned a lot about deploying millimeter wave microwave hops for our customers:
- Rain outage approximately doubles in each higher millimeter wave band, e.g. 18 to 23 GHz
- Rain outage is directly proportional to path length—assuming a constant fade margin for each hop
- Rain outage in tandem-connected short hops is the same as for a single long hop—if they have the same fade margin
- Multipath fading in optimally aligned millimeter wave hops does not occur during periods of heavy rainfall, so the entire path fade margin is available to combat rain attenuation fades
More information about assessing rain-induced attenuation is available in our white paper, Rain Fading in Microwave Networks.
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Evolution of Microwave: History of Wireless Communications
- July 22, 2011
- Aviat Networks, backhaul, Business, Dick Laine, Internet Protocol, microwave, NASA, Nikola Tesla, Telecommunication, Telecommunications, wireless, Wireless Gigabit Alliance
This image of microwave energy in a "total sky" picture of the known universe shows it's everywhere in primordial space, more than 13 billion years ago.
Microwaves are as old as the beginning of the universe. Well, they’ve been around for at least 13.7 billion years—very close to the total time since the Big Bang, some 14 billion years ago. However, we don’t want to go that far back in covering the history of microwave communications.
Having just observed the 155th anniversary of the birth of Nikola Tesla, arguably the most important inventor involved in radio and wireless communications, this is a good time to take a broader view of the wireless industry. If you have been in the wireless transmission field for some time, you are probably familiar with Dick Laine, Aviat Networks‘ principal engineer. He has taught a wireless transmission course for many years—for Aviat Networks and its predecessor companies.
The embedded presentation below comes from one of those courses. In a technological field filled with such well-educated scientists and engineers from some of the finest universities and colleges, it’s hard to believe that microwave solutions and radio itself started in so much controversy by men who were in many cases self-taught. Dick’s presentation goes over all of this in a bit more detail. Hopefully, it’s enough to whet your appetite to find out more. If you like the presentation, consider hearing it live or another lecture series on wireless transmission engineering at one of our open enrollment training courses.
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