This is Microwave starting from 300MHZ to about 60GHZ

1. This is Microwave starting from 300MHZ to about 60GHZ CHAPTER 0

2. The aim of this Course is to Give a) Basic notions in Radio Propagation at microwave frequencies, b) application to Radio Link Design in the frequency range from about 450 MHz up to 60 GHz. • Means : - Course notes - Lab simulators

3. Prerequisites: - basic notions in: - Modulation techniques, - Radio equipment and systems - Elementary electromagnetic physics. • Conclusion : • Course objective : actively involving the reader in navigating through the text and in practicing with exercises in the field of microwave link design. 

4. Introduction To MW links • In telecommunications, information can be analog or digital. • since the 1970’s , MW Analog systems have been almost completely replaced by digital systems. • Now even analog traffic, such as voice calls, are converted to digital signals ( sampling), to facilitate long distance transmission and switching.

5. Terrestrial MW systems have been used since the 1950’s( wartime radar technology). • Today, modern digital microwave radio is world widely deployed to transport information over distances of up to 60 kilometers ( sometimes farther). • Microwave radio is totally transparent to the information carried : which can be voice, data, video, or a combination of all three.

6. Transport can be in a variety of formats : • circuit-switched Time Division Multiplex (TDM) • packet-based data protocols such as ATM, Frame Relay or IP, Ethernet. • In some cases, packetized data can be overlaid on a TDM frame structure such as: - PDH, - SDH or SONET.

7. Microwave radio advantages over cable/fiber-based transmission: • Rapid Deployment • No right-of-way issues – avoid all obstacles • Any requirement to seek permissions :cost & time delays. • Flexibility: simple redeployment & capacity adjustment.

8. Losing customers ≠ Losing assets as in Cables & fibers • Easily crosses city terrain (extremely restricted,& very expensive, to install fiber in city terrains and street crosses). • Operator-owned infrastructure - no reliance on competitors. • Low start-up capital costs : independent of the link distance.

9. Minimal operational costs. • Radio infrastructure already exists (rooftops, masts and towers). • Microwave radio is not susceptible to catastrophic failure ( cable cuts,) and can be repaired in minutes instead of hours or days. • Better resistance to natural disasters (flood, earthquakes). • where the fiber was not always available (the radio is only choice)

10. Fiber is very cost effective where extremely high bandwidths are required. • However, in the access portion of the network, where the maximum capacity requirements are less than STM-4,radio has an obvious advantage. • Note STM1 = 155 Mbits ; STMn = n*155Mbits

11. The 3 basic components of the radio terminal • Two radio terminals are required to establish a MW “hop”. • 1- digital modem interfaces with digital terminal equipment, converting customer traffic to a modulated radio signal; • 2- a radio frequency (RF) unit : Frequency converter + RF amplifier up to around 1 watt. • 3- a passive parabolic antenna to transmit and receive the signal.

12. 2-Basic configurations for MW terminals • 1-Non-protected, ( 1+0) : - Any major failure component will result in a loss of customer traffic. - cost-effective when traffic is non-critical, or where alternate traffic routing is available. • 2-protected (1+1) : Main + hot standby (Monitored Hot Standby (MHSB)) - twice expensive, but No loss of customer traffic.

15. 3- Space Diversity • 4- Frequency Diversity • 5- Polarization diversity • 6-Angle diversity • In addition, Some radios are fitted to use ODU attached directly to the back of the antenna, eliminating antenna feed lines and attendant feed line losses).

16. Used to reinforce the radio dispersive fade margin . The new technology of Mw radio don’t need this type of diversity

18. Two very important characteristic of digital MW transmission is: A- immunity to noise B- the ability of the radio to operate in the presence of adverse environmental conditions.

19. A- immunity to noise • Noise refers to the effects caused by unwanted electromagnetic signals that interfere and corrupt the received signal.

20. Microwave systems operate in so-called “licensed” frequency bands between 2 and 38 GHz (tightly regulation the use of these frequencies ensure that each operator will not cause interference to other links operating in the same area). • The frequency band characteristics are also tightly specified on a worldwide basis by ITU.

21. Equipment are controlled, to meet stringent specifications ( ITU standards, National as FCC and ETSI). • This is in contrast to the “unlicensed” frequency bands of 2.4 and 5.8 GHz : No control, Unlicensed systems themselves incorporate countermeasures to avoid noise and interference, such as spread-spectrum transmission

22. B- the ability of the radio to operate in the presence of adverse environmental conditions. • a perception that microwave is still unreliable due to “fading” . • This is largely a remnant of the analog days. • However, digital radio systems today are able to counteract fading effects in a number of ways

23. Fading is known to occur as a result of primarily two phenomena. 1- Firstly, multipath interference affects mainly lower frequencies below 18 GHz. This happens when the reflected signal arrive slightly later than the direct signal path .it reduces the ability of the receiver to correctly distinguish the data carried on the signal.

24. Fortunately, modern radio systems can compensate for this form of interference through countermeasures such as: • signal equalization [using DSP-filtering to cancel the echoes (pre-echoes & post-echoes) due to Multipath]. • Forward Error Correction, • diversity receiver configurations. Multipath fade measurement parameter is often called the reliability of the link )( (ذا ثقة)-

25. 2- Secondly, precipitation, mostly in the form of rain, can severely affect microwave radio systems in the higher frequenciesabove 18 GHz. Microwaves cannot penetrate rain, so : the heavier the downpour, and the higher the frequency, the greater the signal attenuation. Rain fade measurement parameter is often called the availabilityof the link

26. Although there is noway to counteract rain fade other than higher transmission power. The mechanisms of rain fade are very well understood: models have been developed by the ITU to enable links to be planned within extremely accurate tolerances based upon particular rainfall profiles.

27. Conclusion : As a result, modern microwave systems can be designed for extremely high link total availabilities in excess of 99.999%, translating to link downtimes of literally seconds annually, which is easily comparable to that provided by supposed “error-free” optical fiber systems. • Note : total availability concerns the 2 types of the fade

28. Microwave applications • Mobile Cellular Networks • to provide service for customers and to generate immediate revenue, cellular carriers need to connect their cell sites to switching stations, and have chosen microwave due to: • its reliability • speed of deployment • cost benefits over fiber or leased-line alternatives.

29. Microwave radio will be heavily deployed in the emerging 2.5 and 3G mobile infrastructures: More data usage • greater numbers of cell sites.

30. Last Mile Access • A significant proportion of business premises lack broadband connectivity: Wireless provides the perfect medium for connecting new customers to overcome the last mile bottleneck. • Even if an operator chooses to use unlicensed or multi-point wireless technologies to connect customers, high capacity microwave provides the ideal solution for backhaul of customer traffic from access hubs to the nearest fiber

31. Private Networks: • Companies now have high speed LAN / WAN network requirements and need to connect parts of their business in the same campus, city or country. • Microwave radio is able to provide rapid, high capacity connections that are compatible with Fast and Gigabit Ethernet data networks, enabling LANs to be extended without reliance on fiber build-out.

32. Disaster Recovery • Natural (earthquakes, floods, hurricanes ) and man-made (terrorist attack and wars) disasters can wreak havoc on a communications network: Microwave is often used to restore communications when transmission equipment has been damaged by or other natural disasters, or man-made conflicts such as ( Kuwait, Serbia and Kosovo)

33. The Digital Divide Microwave radio plays a key role in bridging the digital divide : quickly establish a network of access hubs and high-speed backhaul network to bring advanced communications services to areas that would normally have to wait.

34. Developing Nations Microwave has traditionally allowed developing nations the means of establishing state-of-the-art telecommunications quickly over often undeveloped and impractical terrain ( deserts, jungle or frozen terrain where laying cable would be all but impossible.

35. Control and Monitoring • Public transport organizations, railroads, and other public utilities are major users of microwave. • These companies use microwave to carry control and monitoring information to and from power substations, pumping stations, and switching stations.

36. Chapter 1 This is the DB

37. CH 1- what are the decibels • A- Understanding db & db units : A- db : The ratio of 2 signals may be expressed in db by : in case of voltages : V1/V2 ( V2/V1)db = 20 log10 ( V2/V1) in case of Powers : P1/P2 ( P2/P1)db = 10 log10 ( P2/P1)

38. Example : a signal if 10 w is applied to long transmission line . The power measured at the load end is 7 W. What is the loss in db • Solution :

39. Table of some common ratios

41. B) : - db-power units - dbw : is the unit of power expressed relatively to 1W P(dbw) = 10 log10 P(w) - dbm : is the unit of power expressed relatively to 1mW P(dbm) = 10 log10 P(mw) Attention : 0dbw = 30dbm= 1W 0 dbm = -30dbw = 1mw

42. P (dbm) = P(dbW) + 30 P(dbW) = P (dbm) -30

43. Example Problem • If the two antennas in the drawing are "welded" together, how much power in dbm will be measured at point A? (Line loss L1 = L2 = 0.5) –suppose no ideal antenna coupling • Multiple choice:a. 16 dBmb. 28 dBmc. 4 dBmd. 10 dBme. < 4 dBm

44. Answer: • The antennas do not act as they normally would since the antennas are operating in the near field. They act as inefficient coupling devices resulting in some loss of signal. In addition, since there are no active components, you cannot end up with more power than you started with. The correct answer is "e. < 4 dBm." • 10 dBm - 3 dB - small loss -3 dB = 4 dBm - small loss

45. Example : Convert 10dbm in dbw ; -2dbw in dbm Solution : given P(dbW) = P (dbm) -30 = 10-30 = -20 dbW P (dbm) = P(dbW) + 30 = -2 + 30 = 28 dbm Example : consider the 2 following configurations 10dbm ? Gain 3db Gain 10db

46. C) - db-voltage units - dbmv : is used in RF receiver in which the system impedance is 50 Ω. It is the unit of voltage expressed relatively to 1mv v(dbmv) = 20 log10 v(mv)

47. dbµv : is used in RF receiver in which the system impedance is 50 Ω. It is the unit of voltage expressed relatively to 1µv : v(dbµv) = 20 log10 v(µv) Example : The received RF effective voltage at the input of radio receiver is 0.5mv . Find the input voltage in dbµv & the input power in dbm Solution

48. -Field db units : Electromagnetic field a- Electric field E in dbµv /m E (dbµv/m) = 20 log10 E (µv/ m) b- Magnetic field H = E/377 where H in A/m and E in v/ m

50. Power and Field Db-units