Microwave Link Design Sample

Introduction Microwaves are generally describes as electromagnetic waves with frequencies that range from approximately 500 MHzto 300 GHz or more. Therefore, microwaves signals, because of their inherently high frequencies, have relatively short wavelengths, hence the name” micro” waves. For example, a 100 GHz microwave signal has a wavelength of 0.3 cm, whereas a 100 MHz commercial broadcast-band FM signal has a wavelength of 3 m. the wavelengths for microwave frequencies fall between 1 cm and 60 cm, slightly longer than infrared energy. For full duplex (two-way) operation as is generally required of microwave communications systems, each frequency band is divided in half with the lower half identified as the low band and the upper half as the high band. At any given radio station, transmitters are normally operating on either the low or the high band, while receivers are operating on the other hand. There are many different types of microwaves systems operating over distances that vary from 15 miles to 4000 miles in length. Intrastate or feeder service microwave systems are generally categorized as short haul because they are used to carry information for relatively short distances, such as between cities within the same state. Long haul microwaves systems are those used to carry information for relatively long distances, such as interstate and backbone route applications. Microwave radio systems capacities range from less than 12 voice-band channels to more than 22 000 channels. Early microwaves systems carried frequency-division-multiplexed voice-band circuits and used conventional, no coherent frequency modulation techniques. More recently developed microwave systems carry pulse-code-modulated time-division-multiplexed voice-band 2 circuits and used more modern digital modulation techniques, such as Phase Shift Keying (PSK) or Quadrature Amplitude Modulation (QAM). Capabilities of Microwave Microwave transmission is generally defined as the transmission of electromagnetic waves whose frequency falls approximately in the range between 1 Gigahertz and 50 Gigahertz (wavelengths of 30 cm to 6 mm). The propagation through the atmosphere of signals in this frequency range exhibits many of the properties of light, such as line-of-sight transmission, reflection from smooth surfaces, etc. Microwave systems have many applications in the telephone industry because high quality circuits can be derived for intertoll trunks, toll connecting trunks, extended area service trunks, subscriber service and special services. Microwave is also suitable for transmission of black and white or color television, data, and data under voice, with negligible impairment from impulse noise, delay distortion, frequency error, frequency response, or steady state noise. Another attractive aspect of microwave is the ease with which channels can be added or removed after the basic radio frequency (RF) and carrier multiplex equipment is installed. Certain types of RF equipment will carry up to 2000 or more voice channels without any change in the basic RF equipment. The problems associated with cable facilities such as physical damage, induction noise, right-of way problems, circuit expansion limitations and similar problems are reduced with the use of microwave. The initial cost of a microwave system depends on the type of radio frequency and multiplex equipment used the number of channels, the number of hops in a system, 2 the terrain, the type of antennas, the cost of the necessary towers and other factors. In some cases microwave will require a lower initial investment, provide greater reliability, and have lower operating costs and maintenance than cable facilities. It is highly desirable to use digital microwave equipment for all new installations in order to eventually achieve a complete integrated digital network. The only exception to this would be in the event that a borrower wants to use the microwave equipment to carry television signals. Analog equipment is the best choice for the current standard television channel. The input and output baseband signal for a digital microwave radio is a single bit stream. This may range from approximately 1.544 Mb/s to approximately 144 Mb/s. The baseband signal is used to modulate a radio frequency carrier. The RF carriers used range from 2 GHz to 24 GHz. COMPONENTS OF A MICROWAVE SYSTEM Transmitters and Receivers. The basic building blocks of a microwave system are the radio frequency (RF) transmitters and receivers. These units make it possible to send and receive information at microwave frequencies. Most microwave transmitters are capable of an output power of one watt or more. A transmitter used in a terminal location has provisions for modulating the RF carrier with baseband signals from the carrier multiplex equipment. Receivers are capable of providing a useable baseband output with received microwave signal levels as low as -80 dBm. A terminal receiver includes a demodulator to provide the baseband output to the carrier multiplex. 2 and to keep all transmission line lengths short. Transmission lines provide the means of coupling the transmitter and receiver to the antenna. An effective gain of 25 to 48 dB over an ommi-directional antenna is possible depending upon the size of the antenna and the microwave frequency used. It is used at microwave 2 . A waveguide is a hollow metal duct which conducts electromagnetic energy. This results in the most efficient transmission of radiated power with a minimum of interference.7 dB per hundred feet at 6 Gigahertz (GHz) to about 3. These channels are derived using multiplex equipment which can combine several hundred channels for transmission over one RF channel in a single bit stream. water. or debris from accumulating on a microwave antenna. Transmission Lines. so precautions should be taken to use the correct type of line for the radio equipment used. The use of a radome results in lower antenna gain. A parabolic or a horn antenna is used in microwave systems to concentrate radiated energy into a narrow beam for transmission through the air.0 dB per hundred feet at 11 GHz. Radomes. Heated radomes are available for use in areas where severe ice and snow conditions exist. ice. A typical type of waveguide has a loss from about 1. The radiated output power of the transmitter will be substantially reduced if the transmission line is incorrectly used or if its length is too long. A radome is a protective covering used to prevent snow. Waveguide.Carrier Multiplex. There are two types currently available: waveguide and coaxial cable. This type of transmission line can be used for distances of a few feet up to several hundred feet. Antennas. The microwave RF equipment has a wide bandwidth which is capable of carrying many channels of information. elliptical. The cost of coaxial cable is less than waveguide and should be used when possible. At low microwave frequencies. or circular crosssection. the air dielectric coaxial cable has less attenuation for a given diameter. aimed at the reflector. pressurized air dielectric coaxial cable is used with higher capacity systems because the return loss characteristics of foam dielectric lines may be a significant distortion contributor in such systems. while the antenna is mounted horizontally at the base of the tower. coaxial cable can be used as the connecting facility between the transmitter. 7/8" diameter coax can be used satisfactorily for short runs. Reflectors. the cable diameter. A reflector may be mounted at a 45 degree angle at the top of the tower. All waveguide runs are pressurized. the type of dielectric. This is not usually a consideration in systems of low channel capacity. The coaxial cable can have either a pressurized air or expanded polyethelyne (foam) dielectric between conductors. The length of a waveguide run is more critical at higher frequencies since attenuation increases with frequency. The microwave 2 . The loss of coaxial cable depends on the type of conductor. Coaxial cable with a diameter of one inch or more should be used for long cable runs. Extreme attenuation of radio signals above 2 GHz in the coaxial cable generally prohibits its use at the higher microwave frequency bands.frequencies above 2 GHz and can have either a rectangular. Coaxial Cable. In general. and the operating frequency. 2 Ghz or less. depending upon the system operation requirements. A passive reflector can sometimes be used in systems operating near a power substation to avoid the electromagnetic interference (EMI) potential in place of using long runs of waveguide connected to a parabolic antenna at the top of the tower. however. receiver and antenna instead of waveguide. Where temperature and humidity variations exceed the operating limits of the microwave 2 . the microwave frequency band used. the antenna mounting heights are critical and the optimum height may be less than the maximum height available on the tower. There are some situations. However. A waiver from the FCC is required. and the required reliability. Microwave equipment should be located in the central office equipment building when possible. Guyed or self-supporting towers are available for use on microwave systems. and sent in a direction of propagation to the other end of the radio path. when RF equipment must be located remotely from a central office building. the distance between the transmitting and receiving ends of a path. The tower must be high enough to provide a lineof-sight path above any obstructions. but in some cases the difficulty of acquiring enough land for guying prohibits the use of guyed towers. however. Usually a simple prefabricated building is sufficient. the propagation characteristics. as in the case of an active RF repeater. Buildings. just as though the antenna was radiating directly from the top of the tower. installed) of a self-supporting tower.signal is radiated from the antenna. Towers. The towers used in microwave systems must be rigid to prevent antenna deflection during wind or ice loading conditions. A guyed tower is about one-third the cost (per foot. The height of the tower is determined by the terrain. If reflection interference is a problem. this type "periscope" or "fly swatter" antenna system will not be authorized by the FCC under ordinary circumstances because of its interference potential with communications satellites. In these situations some type of building must usually be provided for equipment protection. reflected off the reflector. fuel cell or solar energy. Where alarms from a large number of unattended stations are reported to a central maintenance control center. When microwave equipment is located in a central office building. it is imperative that some type of standby power source be available for circuits derived by microwave. In some cases. When a microwave system has remote unattended stations.equipment. Standby power equipment should be provided at microwave terminals or active repeater locations to maintain system operation in the event of a commercial power failure. However. an engine-generator or in some cases a thermoelectric generator. thermoelectric generators or fuel cells can be used when the power requirements of the microwave equipment are low. Alarm Systems. 2 . Primary power sources for RF equipment may be DC or AC as specified by the purchaser. Central office batteries or 117 volts AC commercial power may be used. Primary and Standby Power Equipment. The stand-by power source may be batteries. floods and other disasters which may cause commercial power outages. itis desirable to have an alarm system which will report faults from the remote location to an attended office via the microwave signal. at remote sites standby power must be provided specifically for the microwave equipment. stand-by power is usually available from central office equipment batteries or an engine-generator. Therefore. Communication circuits are very important during times of emergency such as storms. These alarms will expedite the maintenance of microwave systems and reduce the circuit outage time. a heater or air conditioner is required to keep the equipment within its operating temperature range. attenuation due to trees and buildings in the front of the antenna be propagated and back by the ionosphere.The ratio of the input quantity to the output quantity.the horizontal pointing angle of an earth station antenna. assigned to a channel Baseband. Antenna .a metallic conductor system capable of radiating and capturing electromagnetic energy. including guard bands. Clutter Loss. A single message channel is baseband. Azimuth angle .describes the modulating signal (intelligence) in a communication system. Attenuation . either the southern or northern most point of the horizontal. 2 . Critical Angle.is the horizontal angular distance from a reference direction.is equal to the square root of the ratio of its magnetic permeability to its electric permittivity.the maximum range of frequency.consideration is often given to a computer-based alarm reporting system which prints out all changes in status at each station with time and date information.the reduction in power density due to non-free space propagation.a maximum vertical angle of frequency at which it can be propagated and still be refracted back by the ionosphere. Azimuth. Definition of Terms Absorption . Characteristic Impedance of Free Space. Bandwidth.the reciprocal of gain . Digital Modulation.is the line of signal (LOS) path directly between transmit and receive antennas (this is also called the direct waves). Direct waves. Diffraction . usually gradual.is the transmitted of digitally modulated analog signals (carriers) between two or points in a communications system.used to reference the power level at a given point to one milliwatt.the modulation or redistribution of energy within a wave front when it passes near the edge of an opaque object.(see free space path) Dispersive Fade Margin.lines – European digital carrier system. Decibel (dB). Free Space Path. It is the phenomenon that allows light or radio waves to propagate (peek) around corners.the basic yardstick used for making power measurements in communications. that are caused by changes in the transmission medium.gains in the equipment which are factored in because of technical improvements on the system and how they improved the information signal itself. Field intensity . dBm. Fading. 2 .Critical Frequency.the highest frequency that can be propagated directly upward and still be returned earth by the ionosphere.variations in the field strength of radio signal. E. Flanges.the intensity of the electric and magnetic fields of an electromagnetic wave propagating in free space.interconnect parts of a microwave antenna system together. which is the true mean earth radius. Guard Band.the loss incurred by an electromagnetic wave as it propagates in a straight line through vacuum with no absorption or reflection of energy by nearby objects. on hertz. 2 .the rate at which energy passes through a given surface area.a narrow frequency band provided between adjacent channels in certain portions of the radio spectrum to prevent interference between stations. Half Duplex.Free Space Path Loss. Frequency. Sometimes called “surface waves”. Polarization . Full Duplex (FDX). Fresnel zones. K.described the amount of the front lobe power to the back lobe power of an antenna.the ratio of a hypothetical effective earth radius over 6370 km. Ground Wave . Microwave communication. the term usually used in describing frequency is cycle per second.a high radio frequency link specifically designed to provide signal connection between two specific points. Great Circle Distance. Maximum Usable Frequency (MUF).the number of cycle computed per second by an alternating quantity.the highest frequency that can be used for skywave propagation between two specific points on earth’s surface.data transmission is possible in both directions but not at the same time. Power Density.an electromagnetic wave that travels along the surface of earth.(see duplexing).it is the shortest distance between any two points on a sphere.Factor.orientation of the electric field vector in respect to the surface of the earth. Waveguide.the ability of electromagnetic transmission to bounce off a relatively smooth surface. Skip distance (ds) – the minimum distance from a transmit antenna that a sky wave of given frequency (which must be less than the Maximum Usable Frequency (MUF)) will be returned to earth. 2 .(see ground wave).free-space propagation of electromagnetic waves.the in direction of a ray as it passes obliquely from one medium to another with different velocities of propagation.the curvature of earth presents a horizon to space-wave propagation.a special type of transmission line that consist of a conducting metallic tube through which high frequency electromagnetic energy is propagated. Radio Horizon. Reflection . Receiver threshold . Surface wave .Radio Frequency (RF) Propagation. Refraction.the minimum wide band carrier power (Cmin ) at the input to a receiver that will provide a usable baseband output. Although the link is only 59 km long. we compute for the vertical inclination of the antenna. 2 . It operates in the 7. Since the elevation of the site A and site B are different. Using QPSK modulation the radio unit has an enough transmit power at both site and have a much lower receive threshold. This microwave radio link has a line type of 1xE3 with a rate of 34. over water link supports the wireless communication between Sagnay. For the difference in height of 286m. 10 video channels. and to avoid diffraction loss and clutter loss. the height restriction on the tower antenna required 100m at both site to provide adequate path clearance. Catanduanes. Camarines Sur and San Andres. The connectivity requires 10 voice channels.Description of the link This long. This frequency band was chosen since the rain attenuation at these frequencies will not be a limiting factor in the link reliability. 10 data channels and 10 spare channels which would be required for future expansions.20 GHz common carrier band allocated to fixed point-to-point service.89 GHz to 8. by using trigonometry we found that the vertical inclination of the antenna is 0̊ 16’ 39.368 Mbps and a capacity of 480 channels.85”. 5” LATITUDE 130 34’ 3” 13o 34’ 3” Longitude: 123 o 31’ 22.13˚ 34’ 3” = 0˚ 4’ 12” 2 . Camarines Sur LONGITUDE 1230 31’ 22.5 “ 130 38’ 15” Computation for azimuth angle C= Longitude B – Longitude A = LOB – LOA = 124˚ 3’ 52. Catanduanes 1240 3’ 52.MICROWAVE PLANNING Condition: Path length: 59 km Reliability requirement: 99.5” .5” SITE B: San Andres.5” = 0˚ 32’ 30” ½C = 0˚ 16’ 15” (LB + LA) = 13˚ 38’ 15” + 13˚ 34’ 3” = 27˚ 12’ 18” ½(LB + LA = 13˚ 36’ 9” (LB .368 Mbps and a capacity of 480 channel.123˚ 31’ 22.LA) = 13˚ 38’ 15” .5” LOCATION SITE A: Sagñay.9999% Configuration: Non-protected (1 + 0) Traffic capacity: 1 x E3 with a rate of 34. Site A: Latitude: Site B: Latitude: 13o 38’ 15” Longitude: 124 o 31’ 52. ½(LB – LA) = 0˚ 2’ 6” Log tan ½ (Y+X) = log cot ½ C + log cos ½ (LB – LA) – log sin ½ (LB + LA) tan½ (Y+X) = log -1 [log cot ½ C + log cos ½ (LB – LA) – log sin ½ (LB + LA)] ½ (Y+X) = tan -1 {log -1[log cot ½ C + log cos ½ (LB – LA) – log sin ½ (LB + LA)]} ½ (Y+X) = tan -1 {log -1 [log cot 0˚ 16’ 15” + log cos 0˚ 2’ 6” – log sin 13˚ 36’ 9”]} ½ (Y+X) = 89˚ 56’ 10.9”]} ½ (Z) = 0˚ 31’ 52.69” Log tan ½ (Y-X) = log cot ½ C + log sin ½ (LB – LA) – log cos ½ (LB + LA) tan ½ (Y-X) = log -1[log cot ½ C + log sin ½ (LB – LA) – log cos ½ (LB + LA)] ½ (Y-X) = tan -1{log -1 [log cot ½ C + log sin ½ (LB – LA) – log cos ½ (LB + LA)]} ½ (Y-X) = tan -1{log -1 [log cot 0˚ 16’ 15”+ log sin 0˚ 2’ 6”.log cos 13˚ 34’ 3”]} ½ (Y-X) = 7˚ 34’ 20.91” Log tan ½ (Z) = log tan ½ (LB – LA) + (Y+X) – log sin ½ (Y-X) tan½ (Z) = log -1[log tan ½ (LB – LA) + (Y+X) – log sin ½ (Y-X)] ½ (Z) = 2 {tan -1[log tan 0˚ 2’ 6” + log sin 89˚ 56’ 10.91” 2 .log sin 7˚ 34’ 20.69” .26” + 7˚ 34’ 20. 91” Y = 97˚ 31’ 31.02 km Azimuth Angle Y = ½ (Y+X) + ½ (Y-X) Y = 89˚ 56’ 10.12 D = 59.78” 2 .D = Z *111.69” + 7˚ 34’ 20.69”.26” *111.6” X = ½ (Y+X) – ½ (Y-X) X = 89˚ 56’ 10. D = 0˚ 31’ 52.12 Where: D = distance in km.7˚ 34’ 20.91” X = 82˚ 21’ 49. 2 . Site A: Sagñay.19 km2 (41.82.94 degrees Celsius Maximum temperature.7 degrees Celsius Mean humidity.6 Indicator for occurrence of: thunder.8 sq mi) Barangays – 19 Barangays Mean temperature.33.108.3.99.40 square kilometer Barangays – 27 Barangays Mean temperature.6 Site B: San Andres.1.29 082 (2007) Land Area .25.92 degrees Celsius Mean humidity.1 km/h Maximum wind speed-240 km/h Indicator for occurrence of: rain or drizzle.72 mm Mean wind speed. Cantanduanes Population .31.8.781 (2007) Land area – 252.19.9 Indicator for occurrence of: thunder.46 mm Mean wind speed.01 % Precipitation amount.28.1.9 km/h Maximum wind speed-225 km/h Indicator for occurrence of: rain or drizzle.430.94 % Precipitation amount.89. Camarines sur Population .27.9 2 .76 degrees Celsius Maximum temperature. single polarized 4 = 4 ft.125 GHz – 8.25 ROHS Flange: Antenna: UBR 84 VP4-71W Where: VP = unshielded.05-10.000 Frequency band required. 1. Connector: BNC F/F NI/SI UG-914/U 8 GHZ VSWR 1.00 GHz Internal dimension = 1.122 x 0.Transmitter and receiver equipment specifications CFQ series 8 GHz digital microwave radio unit Frequency range: 7.7 GHz – 8.2 m in diameter 71W = 7. 8 GHz for 60 km 2 .3 GHz Waveguide: WR112 Frequency = 7.5 GHz Type of map Topographical Map Scale = 1:250.497 in.. 25 MHz High band range: 8059.70 MHz + 140 MHz = 7887. of duplex channels = 7955.70 MHz 28 MHz = 7.70 MHz High Band Frequency 8059 MHz + 140 MHz = 8199.57 MHz Duplex spacing: 311.25 MHz . Frequency band: 8 GHz Frequency range: 7.32 MHz Channel bandwidth for 1x E3: 28 MHz No.41 (7 channels) Selecting 5 channel spacing above the high band and low band edge: 28 MHz * 5 = 140 MHz Low Band Frequency 7747.7 GHz to 8.70 MHz to 7955.02 MHz to 8266.Channel plans available.3 GHz Low band range: 7747.02 MHz 2 .7747. Minimum elevation of site A and site B.75* (4/3)] h = 51.19 m 2 .75* k) Where: d = (path length in km)/2 h = minimum site elevation in m. k = 4/3 h = 29.52/ [12. h = d2/(12. 2 .Table plotting points along the path. 2 . 2 . 2 . 18 m L = Lk + LF + LFH = 51.Determining minimum reliable tower height Lk = d1d2/ 12.18 m + 14.3 * F % * L = Lk + LF + LHF Lk = 29 *30 12.60 * LF = 14.36 m Where: L = clearance criteria in meters Lk= curvature factor in meters Lf = fresnel factor in meters LFH = arbitrary fixed height in meters d1 = distance from site A to point.75* k Lf = 17. in kilometer d2= distance from site B to point.3 * 0.18 m LF = 17. in kilometer D = path distance in kilometer F% = fresnel zone percentage factor f lower = low band transmit frequency in GHz Clearance Criteria At Fixed Height of 386 Meters 2 .18 m + 386 m L = 451.75 *(4/3) Lk = 51. Reflection Point looking from Site A (Transmitter at 100 m above MSL) 2 . Fade Margins 2 . 45 + 20 log10 (f * d) FSL = 92.6) = 0.89 * 59) FSL = 145.2624 dB/m) (0.2 m in diameter (8 GHz) with Mid Band Gain of 37.6 m flexible waveguide in site A and site B) Connector Loss = 0.45 + 20 log10 (7.2624 dB/m) (0.6) = 0.81 dB For High Band: 2 .5 dB Waveguide used = WR112 (0.1574 dB Antenna used = 1.Radio Configuration = Outdoor Mounted RF Module (ODU) Transmit Power = 32 dBm Receiver Threshold (1 x E3 at 8 GHz) = -86 dBm Flexible Waveguide loss: Low band frequency = (0.1574 dB High band frequency = (0.5 dB Free Space Loss (FSL): For Low Band: FSL = 92. 81 37.87 UNITS dBm dB dB dB dB dB dB dB dB dBm dB Computation for High Band Frequency (8.14 dB Where: f = frequency d = path length in Km Computation for Low Band Frequency (7.50 0.45 + 20 log10 (f * d) FSL = 92.89 GHz) PARAMETERS Microwave Radio Output Power Connector Loss (TX) Flexible Waveguide Loss (TX) Antenna Gain (TX) Free Space Loss (FSL) Antenna Gain (RX) Connector Loss (RX) Flexible Waveguide Loss (RX) Power Input to Receiver (RSL) Minimum Receiver Threshold Thermal Fade Margin VALUE 32.FSL = 92.50 0.00 42.50 0.16 -39.13 -86.50 145.00 0.16 37.20 GHz) 2 .45 + 20 log10 (8.20 * 59) FSL = 146. 16 -39.14 37.54 UNITS dBm dB dB dB dB dB dB dB dB dBm dB Dispersive Fade Margin Dispersive Fade Margin at 1 x E3 is 90 dB.00 0.46 -86.00 46.PARAMETERS Microwave Radio Output Power Connector Loss (TX) Flexible Waveguide Loss (TX) Antenna Gain (TX) Free Space Loss (FSL) Antenna Gain (RX) Connector Loss (RX) Flexible Waveguide Loss (RX) Power Input to Receiver (RSL) Minimum Receiver Threshold Thermal Fade Margin VALUE 32. therefore it is not included in the computation. Interference Fade Margin Assume that no interference fade margin is given.50 0.50 0.50 0. 2 .50 146.16 37. 2 . 29448 2 .0000387 0.030000 1.0015500 0.065000 1.33(log10 0.0101000 0.1130000 0.2760000 1.0210000 0.0610000 1.880000 0.00887 – 0.264000 1.1540000 1.3500000 kV 0.0335000 0.9790000 0.1240000 0.075000 1.2170000 1.276 – 0.3100000 αV 0.0188000 0.00887 – log10 0.200000 1.89 GHz) M = (log10 f1 – log10 fx)/ (log10 f1 – log10 f2) note: f1 < fx <f2 M = (log10 7 – log10 7.310000 1.0168000 0.312000 1.1670000 0.128000 1.1210000 1.923000 1.0751000 0.9630000 1.0610000 1.0001540 0.963000 0.2330000 0.265000 1.3080000 1.0030100 0.0017500 0.33 (1.929000 Rain Losses CCIR/ITU-R Recommendation 530 rain attenuation For Low Band Frequency (7.00265)] k = 0.332) α = 1.0691000 0.1920000 0.276 – 1.1870000 0.3320000 1.0000352 0.0026500 0.0367000 0.9390000 αH 0.0990000 1.Frequency in GHz 1 2 4 6 7 8 10 12 15 20 25 30 35 40 kH 0.89)/ (log10 7 – log10 10) M = 0.0088700 0.0006500 0.0045400 0.33 k = log10-1 [log10k1 – M (log10k1 – log 10k2)] k = log10-1 [log10 0.0039500 0.0001380 0.2630000 0.0005910 0.00593604 α = α1 – M (α1 – α2) α = 1.000000 0. 20)/ (log10 7 – log10 10) M = 0.44(1.276 – 1.015* 180 D0 = 2.005212732 α = α1 – M (α1 – α2) α = 1.20 GHz) M = (log10 f1 – log10 fx)/ (log10 f1 – log10 f2) note: f1 < fx <f2 M = (log10 7 – log10 8.2619 km where: DE = effective rain path length R0.276 – 0.0.3521) DE = 2.001 = rainfall rate at 0.00265)] k = 0.015* R0.44(log10 0.001% outage Computation for the unit rain attenuation 2 .For High Band Frequency (8.0087 – log 10 0.332) α = 1.0.44 k = log10-1 [log10k1 – M (log10k1 – log 10k2)] k = log10-1 [log10 0.001 D0 = 35* ℓ .3521 DE = D/1 + (D/D0) DE = 59/1 + (59/2.30064 Computation for the effective rain path length D0 = 35 *ℓ .0087 – 0. 20 GHz) k = 0.9306 For High Band Frequency (8.29448 y = k *(R0.001) α y = 0.00593604 (180) 1.89 GHz) A rain = DE * y A rain = (2.4306) A rain = 11.29448 y = 4.1525 dB For High Band Frequency (7.For Low Band Frequency (7.2619) (4.00593604 α = 1.4706 Rain Attenuation For Low Band Frequency (7.001) α y = 0.30064 y = k * (R0.30064 y = 4.89GHz) k = 0.89 GHz) 2 .005212732 (180) 1.005212732 α = 1. 227) + (4.0975 + 1.99 * 10-3] [(7.89 GHz) A0 = [7.19 * 10-3 + (6.4706) A rain = 10.89)2 * 10-3dB/km] A0 = (0.09/ ((7.81/ (f – 57)2 + 1.5)] [(7.0066 dB/km Atmospheric Losses for 59 km = (0.19 * 10-3 + (6.5)] f2 * 10-3 dB/km Where: f = frequency in GHz For Low Band Transmit Frequency (7.892) (10-3) dB/km A0 = 0.81/ (7.19-3 + 0.09/f2 + 0.1120 dB Atmospheric Losses Oxygen absorption loss Computation for absorption loss at a path length of 30 km: A0 = [7.89 – 57)2 + 1.2619) (4.10668) (7.227) + (4.89)2 + 0.0066 dB/km) (59 km) = 0.89)2 * 10-3 dB/km] A0 = [7.A rain = DE * y A rain = (2.3894 dB 2 . 3) + (9/ (7.20)2 + 0.892 + 7.81/(8.0067 dB/km) (59 km) = 0.89 – 323.19 *10-3 + (6.892 * 10-4dB/km] AH2O = (0.02*10-3] [(8.0061 dB/km) (59km) 2 .0061dB/km Water Vapor Loss for 59 km = (0.202) (10-3) dB/km A0 = 0.8)2 + 10] [f2 * α *10-4dB/km] Where: f = frequency in GHz α= water vapor density in gm/m3 should be below 12 gm/m3 Computing for water vapor loss at a path length of 59km For Low Band Frequency (7.20 – 57)2 + 1.08129) (7.20)2 * 10-3 dB/km] A0 = [7.5)][ (8.For High Band Transmit Frequency (8.89 GHz) AH2O = [0.227) + (4.8)2 + 10] [7.067 + (3/f2 + 7.3/ (7.3/(f – 323.067 + (3/7.090266+ 2.3946 dB Water Vapor Loss AH2O = [0.892) (12*10-4) dB/km AH2O = 0.89 – 1833)2 + 6) + (4.19-3 + 0.0067 dB/km Atmospheric Losses for 59 km = (0.20)2 * 10-3dB/km] A0 = (0.09/((8.09947) (8.3) + (9/(f – 1833)2 + 6) + (4.20 GHz) A0 = [7. = 0.3583 dB For High Band Frequency (8.20 GHz) AH2O = [0.067 + (3/8.202 + 7.3) + (9/ (8.20 – 1833)2 + 6) + (4.3/(8.20 – 323.8)2 + 10] [8.202* 10-4dB/km] AH2O = 0.0066077 dB/km Water Vapor Loss for 59 km = (0.0066077 dB/km) = 0.3899 dB Antenna Misalignment A 0.5dB overall in the link budget to compensate the misalignment of the antenna during installation. 2 2 2 00 UNITS dBm dB dB dB dB dB dB dB dB dB dB dB dB dBm dB dB 2 .16 37.00 46.13 dB – (.16 37.16 dB + 37.00 0.81 0. there is no need to compute for the diffraction loss and clutter loss.50 145.50 0.50 dB – 145.39.87 90.50 dB – 0.13 dB TFM = RSL – Receiver Threshold TFM = -39.50 -39.89 GHz RSL = transmitter output – (Tx) waveguide loss + (Tx) Antenna gain – FSL + (Rx) Antenna gain – (Rx) Waveguide loss RSL = 32 dBm – 0.16 RSL = .15 0.39 0. Table of the given and calculated data Computation for low band frequency-Tx = 7.36 11.87 dB PARAMETERS Microwave Radio Output Power Connector Loss (Tx) Flexible Waveguide Loss (Tx) Antenna gain Free Space Loss (FSL) Atmospheric Losses (Oxygen Absorption) Atmospheric Losses (Water Vapor Loss) Rain Attenuation Antenna misalignment loss Flexible Waveguide Loss (Rx) Antenna gain (Rx) Connector Loss (Rx) Power Input to Receiver (RSL) Minimum Receiver Threshold Thermal Fade Margin (TFM) Dispersive Fade Margin VALUE 32.86 dBm) TFM = 46.50 0.Diffraction loss and clutter loss Since there is no point along the path comes closer than 150% first Fresnel.50 0.81 dB + 37.13 -86. 39 10.39.16dB + 37.46 dB Thermal Fade Margin = RSL – Receiver Threshold TFM = .14 dB + 37.00 0.39.50 dB – 0.50 dB – 146.14 0.20 GHz RSL = Transmitter Output – (Tx) Waveguide loss + (Tx) Antenna Gain – FSL + (Rx) Antenna Gain – (Rx) Waveguide Loss RSL = 32dBm – 0.00 UNITS dBm dB dB dB dB dB dB dB dB dB dB dB dB dBm dB dB Flat Fade Margin Calculation for the Flat Fade Margin is given by the formula: FM FLAT = -10 log [10 (-FMthermal/10) + 10 (-FMadj – chan/10) + 10 (-FMint/10) + 10 (-Fmdiff/10)] 2 .Calculation for high band frequency – Tx = 8.46 -86.00 46.16 dB RSL = .11 0.50 0.39 0.54 dB PARAMETERS Microwave Radio Output Power Connector Loss (Tx) Flexible Waveguide Loss (Tx) Antenna gain Free Space Loss (FSL) Atmospheric Losses (Oxygen Absorption) Atmospheric Losses (Water Vapor Loss) Rain Attenuation Antenna misalignment loss Flexible Waveguide Loss (Rx) Antenna gain (Rx) Connector Loss (Rx) Power Input to Receiver (RSL) Minimum Receiver Threshold Thermal Fade Margin (TFM) Dispersive Fade Margin VALUE 32.46 dB – (-86 dBm) TFM = 46.50 146.54 90.16 37.16 37.50 0.50 0.50 -39. 20 GHz) FM EFF = -10 log [10 (-46.89 GHz) FMFLAT = -10 log [10 (-46.20 GHz) FMFLAT = -10 log [10 (-46.89 GHz) FM EFF = -10 log [10 (-46.54/10) + 7 *10 (-90/10)] FM EFF = 46.87 dB For high band transmit frequency – Tx (8.87/10)] FMFLAT = 46.87/10) + 7 *10 (-90/10)] FM EFF = 46.For low band transmit frequency – Tx (7.5386 dB Reliability Calculation K – Q Reliability Calculation U = K – Q f b d c * 10 (-FMeff/10) Where: K – Q = Regional K – Q value f = frequency in GHz 2 .54 dB Composite Fade Margin Calculation for the composite or effective fade margin is given by the formula: FM EFF = -10 log [10 (-FMflat/10) + RD *10 (-FMdsp/10)] Where: RD = Fade Occurance Factor For low band transmit frequency – Tx (7.54/10)] FMFLAT = 46.8685 dB For high band transmit frequency – Tx (8. 8685 dB – 11.2 * 59 3.869 * 10 -7 For high band transmit frequency – Tx (8.372 * 10 -7 Unfaded Reliability is then computed as 1.d = Path length in km b.5* 10 (-46.372 * 10 -7) * 100 % RHB = 99.89 GHz) ULB = 1 *10 -9* 7.c = Regional Climate Factor FMeff = Effective Fade Margin For low band transmit frequency – Tx (7.869 * 10 -7) * 100 % RLB = 99.20 GHz) UHB = 1 *10 -9* 7. b = 1.89 GHz) RLB = (1 – 3. Rain Fade Margin = Effective Fade Margin – Rain Attenuation For low band transmit frequency – Tx (7.15 dB RFMLB = 35.5 * 10 (-46.89 GHz) RFMLB = 46.2 and c = 3.5.2 * 59 3.5386/10) UHB = 4.89 1.unavailability For low band transmit frequency – Tx (7.8685/10) ULB = 3. the unavailability and reliability for link due to rain can be calculated.999961 % For high band transmit frequency – Tx (8.89 1.7185 dB 2 .999956% Using the same value for K – Q of 1*10 -9.20 GHz) RHB = (1 – 4. 484 * 10 -6 Reliability for low band transmit frequency – Tx (7.4286 dB For low band transmit frequency – Tx (7.5 * 10 (-36.4.11 dB RFMHB = 36.For high band transmit frequency – Tx (8.042 * 10 -6)* 100 % RLB = 99.99949 % Reliability for high band transmit frequency – Tx (8.5386 dB – 10.2 * 59 3.042 * 10 -6 For high band transmit frequency – Tx (8.2 * 59 3.4286/10) UHB = 4. M = Average Elevation above MSL 2 .99955 % K – Q Reliability with terrain roughness Taking the standard deviation of regular increments of the path.484 * 10 -6) *100 % RHB = 99.20 GHz) RFMHB = 46.20 GHz) RHB = (1 .5 * 10 (-35.89 1.89 GHz) ULB = 1 *10 -9 * 7.7185/10) ULB = 5.20 1.20 GHz) UHB = 1 *10 -9* 8.89 GHz) RLB = (1 – 5. S = Standard Deviation of the elevations in the path Where: N = number of path length subdivisions between the two end stations M = Average Elevation within the path S = Standard Deviation of the elevation within the path 2 . Path elevations do not include site elevations Sum = Average = 629.00 3254.00 10.22 2 .84 188745. 89 GHz) ULB = (1*10-9 / 56 1.891.5 * 10(-46.5386 /10) UHB = 2.5* 10(-46.SD = SD = 56.2* 593.065 * 10-9 For high band transmit frequency – Tx (8.891.00 Calculation for the K – Q reliability with terrain roughness is given by the formula: U = (K – Q / S 1.3) * 7.20 GHz) UHB = (1*10-9 / 56 1.2* 593.334 *10-9 2 .8685 /10) ULB = 2.3) * f b *dc * 10(-FMeff /10) Where: K – Q = Regional K – Q value f = frequency in GHz d = Path length in km b and c = Regional Climate Factor FMeff = Effective Fade Margin S = Standard Deviation of the terrain elevation (also called Roughness Factor) For low band transmit frequency – Tx (7.3) * 7. 065 * 10-9) *100 % RLB = 99.2 * 59 3.7185 dB For high band transmit frequency – Tx (8.8685 dB – 11.20 GHz) UHB = (1*10-9 / 56 1.891.5 * 10 (-35.3) * 7.11 dB RFM= 36.2 * 593.89 GHz) ULB = (1 *10 -9/561.20 GHz) RFM= 46.7185/10) ULB = 2.394 * 10-8 2 .89 GHz) RLB = (1 -2.4286 /10) UHB = 2.20 GHz) RHB = (1 -2.334*10-9) * 100 % RHB = 99.15 dB RFM= 35.Unfaded Reliability is then computed as: For low band transmit frequency – Tx (7.4286 dB For low band transmit frequency – Tx (7.99999977 % Calculating Rain Fade Margin: RFM = Effective Fade Margin – Rain Attenuation For low band transmit frequency – Tx (7.691 * 10 -8 For high band transmit frequency – Tx (8.99999979 % For high band transmit frequency – Tx (8.89 1.5386 dB – 10.89 GHz) RFM= 46.5 * 10(-36.3) * 7. 89 GHz) RLB = (1 – 2.8685/10) ULB = 7.Reliability for low band transmit frequency – Tx (7.5386 /10) UHB = 8.394*10 -8) * 100 % RHB = 99.691*10 -8) *100 % RLB = 99.0 * 10-7*4*7.89 * 593 * 10(-46.0 * 10-7* c * f * d3 * 10(-FMeff /10) Where: c= c factor value which is equal to 4 for the difficult propagation Condition f= frequency in GHz d= path length in km For low band transmit frequency – Tx (7.89 GHz) ULB = 6.9999976 % Vigants – Barnette Calculation The Vigants – Barnette unavailability formula is given as: U = 6.9999973 % Reliability for high band transmit frequency – Tx (8.20 GHz) UHB = 6.89 * 59 3 * 10 (-46.969*10-5 2 .998 *10 -5 For high band transmit frequency – Tx (8.0 *10-7 * 4*7.20 GHz) RHB = (1 -2. 89 GHz) ULB = 6.7185/10) ULB = 1.9920 % For high band transmit frequency – Tx (8.20 GHz) UHB = 6.4286 /10) UHB = 9.8685 dB – 11.04 * 10 -3 For high band transmit frequency – Tx (8.20 GHz) RFM= 46.5386 dB – 10.4286 dB Unavailability during rain: For low band transmit frequency – Tx (7.969 * 10-5) * 100 % RHB = 99.10 % Calculation for the unavailability due to rain is done: Rain Fade Margin = Effective Fade Margin – Rain Attenuation For low band transmit frequency – Tx (7.11 dB RFM= 36.19858 * 10-4 2 .998 * 10-5) *100 % RLB = 99.89 * 59 3 * 10 (-35.0 * 10-7 * 4 * 7.0 * 10-7 * 4 * 7.89 * 593*10(-36.89 GHz) RLB = (1 -7.89 GHz) RFM= 46.20 GHz) RHB = (1 -8.7185 dB For high band transmit frequency – Tx (8.Unfaded Reliability is: For low band transmit frequency – Tx (7.15 dB RFM= 35. 19858 * 10-4) * 100 % RHB = 99.00 Units DMS DMS m 2 .The reliability during rain: For low band transmit frequency – Tx (7.908% MICROWAVE PATH DATA SHEET Capacity: 1xE3 Low band transmit frequency: 7.04 * 10-3) *100 % RLB = 99. Camarines sur Site B: San Andres.20 GHz Equipment: CFQ series 8 GHz digital microwave radio unit Site A: Sagñay.5” 13o 34’ 3” 100.20 GHz) RHB = (1 -9.89 GHz) RLB = (1 -1.5” 13o 38’ 15” 100.00 High Band Site B 124 o 31’ 52.89 GHz High band transmit frequency: 8. Catanduanes Path length: 59 km Modulation: QPSK Site Information Longitude Latitude Site Elevation (Above Mean Sea Level) Low Band Site A 123 o 31’ 22.89576963 % For high band transmit frequency – Tx (8. 50 0.60 0.00 97 o 31’ 31.00 -86.00 0.00 -86.50 37.999956 99.14 0.54 46.11 Units dB dB dB Site A 32.00 46.50 0.99949 99.Tower Elevation (Above Ground Level) Azimuth From True North 100.999 Units % % % 2 .87 46.99955 99.5386 36.50 0.16 0.50 Site B 32.54 90.36 11.16 0.50 Units dBm dBm dB dB dB dB dB dB Fade Margins Thermal Fade Margin Dispersive Fade Margin Flat Fade Margin Effective Fade Margin Rain Fade Margin Site A 46.00 82 o 21’ 49.87 90.60 0.50 0.6” NW m DMS Equipment Information Transmitter Output Power Receiver Input Threshold Waveguide length Waveguide loss Connector loss Antenna Gain Antenna Misalignment loss Wet/Frozen Antenna loss Path Losses Free Space Loss Oxygen Absorption Loss Rain Attenuation Site A 145.50 37.39 10.999 Site B 99.15 Site B 146.7185 Site B 46.78” NE 100.4286 Units dB dB dB dB dB Path Reliability Unfaded Reliability (one way) Rain Reliability (one way) Link Reliability (Duplex) Site A 99.81 0.00 0.8685 35.999961 99.00 46. 2 . 104 m Parallel section .77 m/s speed Antenna loading 10.5 kN or 6 m2 over the to 10m 2 . thereafter in 4 m increments up to 104 m Foundation Designs Tower Height 30 36 40 46 50 56 60 64 Concrete Volume (m3) 12 17 18 19 26 32 41 45 Rebar Excavation Backfill (kg) 900 1258 1350 1078 1350 2242 3075 3375 (m3) 24 33 36 50 57 60 82 90 (m3) 12 16 18 31 31 28 41 45 72 48 4452 126 78 Antenna Loading Capacity Tower capacity of 92 m tower under the following loading conditions: Maximum survival wind 77.Tower The medium tower has the following physical properties: • • • • • Maximum height .13.10 m Parallel face width .1 m Footprint for 104 m tower .7 m Tower heights – in 2 m increments up to 60 m. 2 . 2 . Equipment Shelter 2 . 2 . 2 . 2 . 2 . 2 . Building Description Framework: The building shall have a complete. Building framework to have a flush wall. self-supporting. 2 . Wall and ceiling structural support system are to be designed to provide load carrying capability for anticipated equipment loads using 16 gauge galvanized steel hat channels behind liner panel for reinforcement as needed. The building framework shall include 8 to 16 gauge. and full trusses on both endwalls which easily allows for future expansion and/or modifications. with locations shown on approval drawings. structural steel frame which does not rely on the exterior panels or roof cover panels for any of its structural strength or framing. galvanized steel structural members. cold-formed. internal. post and beam format with girts and purlins. Roof to have 8 gauges to 14 gauge solid web hot rolled steel trusses. Standing seam roof panels shall be of Galvalume steel. StandingSeam Roofing. Exterior Walls: The exterior walls shall be 18 gauge ribbed G-90 galvanized steel panels with a baked-on PVDF resin-based finish in manufacturer’s standard colors. with a baked-on Kynar 500. and R-30 in the floor. In addition to the insulation in the walls and ceiling. 18 gauge. The insulation system shall provide a minimum of R-19 in the walls. A roof with a pitch of less than 1 inch in 12 shall have a roof covering of mechanically-seamed. PVDF resinbased finish in manufacturer’s standard colors. and shall be removable without any disturbance to interior panels.Insulation: Exterior walls shall have a minimum of 3. 2 . G-90 galvanized. as a thermal break. Properly sized attic space ventilation shall be provided. ribbed steel panels with a baked-on Kynar 500. All openings in walls are to be structurally framed. fiberglass batt insulation and a vapor barrier. Roof to include a matching. an additional 1” cellulose insulation blanket shall be installed over the entire building framework and under the exterior wall and roof panels. and a fully supported 3” overhang. The ceiling shall have a minimum of 6” cellulose insulation and a vapor barrier. PVDF resin-based coating and shall have no visible fasteners on main run.5”. Overlapping roof panels shall be installed with appropriate self-tapping fasteners with integral gaskets. R-24 above the ceiling. with a minimum seam height of 2”. Exterior siding panels to be overlapped and installed with appropriate self-tapping fasteners with integral gaskets. 24 gauge. Cellulose to have a minimum flame spread rating of 5 Roof: A roof pitched 1 inch in 12 or greater shall have a covering of overlapping. Butted seams are not allowed. die-formed ridge cap. and header trim in. Closures: Matching. rake. Interior Finish: The building’s interior walls and ceiling shall be lined with flushfit 22 gauge. Adhesives. jamb. Repair or replacement of exterior panels must be able to be done entirely from outside. roll-formed liner panels. jamb. with concealed fasteners and a baked-on White polyester finish over G-90 galvanized substrate. trimmed. The building interior shall feature a complete matching trim system including base. pre-molded. beneath the roof panels. fascia. 2 . and sealants utilized shall be of types approved for use on this type of structure as required by the appropriate agency or governing body. adhesives. 26 gauge Galvalume material with owner’s choice of standard KYNAR colors. Exterior Trim: The exterior trim package shall include stepped or boxed eave. corner. as covered in section 1.02 of these specifications. Fasteners. closed cell elastomer closures provided by the siding and roof panel manufacturer shall be installed according to the manufacturer’s recommendations at the eave line.sleeved. and Sealants: The fasteners. and provided with external drip caps. header. Minimum floor to ceiling dimension shall be nominal 10’. and ceiling trim Interior Dimensions: The building’s finished interior dimensions shall be no less than 10 ½” in width and length from the exterior dimensions shown on the drawings. and where the trim meets the wall panels. base. Station Layout 2 . The size of each Fresnel Zone varies based on the frequency of the radio signal and the length of the path. As frequency decreases. It is more difficult also to attain a higher reliability in an over water link because of higher reflection coefficient. As the length of the path increases. A Fresnel Zone radius is greatest at the midpoint of the path. and when the path length is increases because of the increase in value of free space path loss. Therefore. the following should be considered. the size of the Fresnel Zone also increases. 2 .Conclusion In designing a microwave communication link. the size of the Fresnel Zone increases. the midpoint requires the most clearance of any point in the path. In a long haul. path terrain conditions. the proper of the transmit equipment should be high enough in order to attain much higher reliability. factor that affect microwave signals and the reliability of the link. choosing appropriate frequencies which may be used for a specific distance. APPENDICES 2 . 2 . 2 . 2 . 2 . 2 . 2 . REFERENCES 2 . com/andrew/eng/product/towers/index.BOOKS: Fundamentals of Microwave Communication with planning guide By: Manny T.com www.commscope.html 2 . Rule Electronic Communication System. Fundamental Through Advance By: Wayne Tomasi INTERNET SITES: www.andrew.com www.globalspec. 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