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DEPARTMENT OF PLANNING AND ZONING
CUSTOMER ASSISTANCE GUIDE
INSTRUCTIONS FOR FILING A BUILDING PERMIT
FOR CO-LOCATION OF ANTENNAS
ON EXISTING TOWERS AND/OR STRUCTURES
REVISED MAY 2006
Step 1:	Consult the attached Zoning Ordinance excerpt regarding conditions for co-location of antennas on existing towers and/or structures.  Note: Conditions vary depending on whether the antennas are to be located on County-owned or leased property (Sec. 3-3.03.F) vs. private property (Sect. 3-3.03.G).
Step 2:	Submit a completed Building Permit Application[1] to the Division of Inspections and Permits, Suite 201, County Services Plaza, 150 Main Street, Prince Frederick, Maryland.  One (1) complete set of construction drawings and site plans must be submitted with the permit application.
	Application numbers (AP#) are assigned by the Division of Inspections & Permits when the application is accepted.  The status of the application can then be checked on-line at:
	www.co.cal.md.us/permlkups/default.aspx
Step 3:	Mail one (1) complete set of construction drawings and site plans, as well as the information described in the attachment entitled, "Telecommunications Facility Design Considerations" to the County's tower consultant:
Jeff Martin, RCC Consultants, Inc.
257 Milford Drive, Middletown, DE 19709-9469
	The consultant will contact the applicant directly if any information is missing or incomplete.  He will contact the Department of Planning and Zoning when his review is complete and the permit is approved.
Step 4:	Once the permit has been approved by the consultant and the Department of Planning and Zoning, the applicant must pay the following fees prior to issuance of the permit:
FEES
(Separate Checks for each fee should be made payable to the Calvert County Treasurer)
Antenna Fee (submitted to the Dept. of Planning & Zoning) = $150.00
Permit Fee (submitted to the Division of Inspections & Permits) = $300.00
Important Telephone #'s:
Jeff Martin, RCC Consultants, Inc.: (302) 376-5887
Division of Inspections & Permits (410) 535-1600 ext. 2552

Excerpt: Section 3-3.02.G, Calvert County Zoning Ordinance

USE

ZONING DISTRICTS

FFD

RCD

RD

WL

APD

HD

I-1

RC

MC

TC

EC

TOWERS:

A.

Tower, Commercial/Governmental on Government Property

C

C

C

C

C

C

C

C

B.

Tower, Commercial on Private Property (no height restriction)

SC

SC

SC

SC

SC

SC

C.

Tower, Commercial on Private Property, less than 75 feet

SC

SC

SC

SC

C

C

C

C

C

D.

Tower, Private/Not-for-Profit, less than 75 feet

C

C

C

C

C

C

C

C

C

E.

Tower, Private/Not-for-Profit, greater than 75 feet

SC

SC

SC

SC

SC

SC

SC

SC

SC

ANTENNAS:

F.

Antenna, Commercial/Governmental on Government Property

C

C

C

C

C

C

C

C

G.

Antenna, Commercial on Private Property

C

C

C

C

C

C

C

C

C

H.

Satellite Dish Antenna; Ground Mounted, greater than three feet in Diameter

C

C

C

C

C

C

C

C

C

I.

Satellite Dish Antenna; Roof Mounted, greater three feet in Diameter

SC

SC

SC

SC

C

SC

SC

SC

SC

J.

Satellite Dish Antenna; Ground or Roof-Mounted, less than three feet in Diameter

P

P

P

P

P

P

P

P

P

K.

Antenna, Private/Not-For-Profit

P

P

P

P

P

P

P

P

P

KEY: C = Must comply with conditions of Section 3-3.03; SC = Requires special exception from Board of Appeals and must also comply with conditions of Section 3-3.03; P = Permitted; Blank = Not Permitted.

 

 

 

	3-3.03 Conditions for Towers and Antennas
		F.	Antenna, Commercial/Governmental on Government Property, provided that:
			1.	A building permit shall be obtained prior to installation of the antenna.
			2.	The antenna shall be attached to public buildings, water towers, or existing towers (including street lights and utility poles) located on government property; and
			3.	If an antenna is installed on a structure other than a tower, the antenna and supporting electrical and mechanical equipment shall be of a neutral color that is identical to or closely compatible with the color of the supporting structure so as to make the antenna and related equipment as visually unobtrusive as possible; and
			4.	The owner of the antenna shall submit a radiation safety analysis demonstrating that the antenna will not pose a health threat to individuals due to excessive radiation emissions and that the antenna is in compliance with current FCC guidelines for human exposure to radio frequency electromagnetic fields.
		G.	Antenna, Commercial on Private Property, provided that:
			1.	A building permit shall be obtained prior to installation of the antenna; and
			2.	The antenna shall be attached to public, commercial or industrial buildings or structures, steeples, smokestacks,water towers, or existing communications towers only; and
			3.	The radio signals emanating from the proposed antennas shall not interfere with the County’s wireless communication systems which include, but are not limited to public safety, administrative and school wireless systems; and
			4.	The owner of the antenna shall submit a radiation safety analysis demonstrating that the antenna will not pose a health threat to individuals due to excessive radiation emissions and that the antenna is in compliance with current FCC guidelines for human exposure to radio frequency electromagnetic fields; and
			5.	If an antenna is installed on a structure other than a tower, the antenna and supporting electrical and mechanical equipment shall be of a neutral color that is identical to or closely compatible with the color of the supporting structure so as to make the antenna and related equipment as visually unobtrusive as possible; and
			6.	A commercial antenna may be approved as an accessory use to any commercial, industrial, or institutional structure, or to any existing approved tower provided that:
				a.	ifattached to a building, the antenna shall not project above the roof line by more than ten (10) feet. If attached to an approved tower, the antenna shall not exceed the maximum height originally approved for the tower.
				b.	theantenna shall comply with the applicable FCC, MAA and FAA regulations, and the applicant shall submit verification of same.

 Telecommunications Facility Design Considerations
Prepared by RCC Consultants, Inc.
for Calvert County, Maryland
April 10, 2002

Objective:  To provide general guidance to the designers and developers of wireless telecommunications systems within the jurisdictional boundary of Calvert County.

Background:  The County is currently operating their emergency communications systems in the upper public safety 800 Mhz band. The information provided in this document is intended only to supplement the County Ordinance.  This information will assist commercial and private wireless engineers in the proper design of their communications sites so that they do not cause interference to the County’s existing and proposed networks as well as ensure their compliance with Federal and State Regulations related to Aeronautical Obstructions and RF Radiation Limitations.

I.  Non-interference Analysis:

There are three types of potential interference to land mobile communications and are directly related to the siting of the commercial system: (A) Co-location Intermodulation interference, (B) Near-far Scenario of interference and (C) obstruction of microwave paths that serve the county telecommunications backbone.

A.  Co-Location Intermodulation Interference

This scenario must be considered when a commercial carrier is proposing to co-locate their wireless system at the same structure where the County systems will operate.  The County has existing systems on commercially-owned towers and on existing county water tanks.  To determine if interference is anticipated, the carriers will need to submit an Intermodulation Study for the site in question.  This study will need to take into account the following sources of interference:

Transmitter Noise                                         Receiver Desensitization
Transmitter Inter-modulation                      Receiver Inter-modulation
Other Radiated Inter-modulation               Transmitter Spurious Radiation
Receiver Spurious Radiation                     Co-Channel Interference
Adjacent-Channel Interference                  Random Noise
Impulse Noise

It is always beneficial to complete an initial Inter-modulation Analysis before the proposed co-location takes place.  With knowledge of potential interference sources/frequency combinations and the use of good engineering practices will result in acceptable performance for all clients with at minimal installation cost for first time.

Included in the carrier’s interference analysis should be a detailed explanation of the proposed RF system configuration, including:

1.  RF System Configuration

Complete, detailed technical sketch showing the entire RF system diagram from the power source to the antenna type.  The sketch should show transmitters, combiners, receivers, multi-couplers, coaxial lines, tower-top amplifiers, antennas and their locations, etc.

2.  Hardware Specifications

Each device within the RF System Configuration should have a basic set of engineering and performance specifications.

3.  RF Piping Diagram

A signal flow diagram shall show all signal gains and losses throughout the entire RF System Configuration.  The information should include specific system settings and alignments.  Antenna azimuths and down-tilt positions to be included.  Final ERP should be identified.

4.  Initial Inter-modulation Analysis

An acceptable IMD should include all of the following:

a.  Calculate all possible IM product frequencies that could potentially interfere with any receivers at the communications site and produce a detailed hit list and summary report identifying the transmitters and receiver involved.

b.  Calculate all transmitter radiated power levels considering line loss, filter loss, other associated losses and antenna configurations.

c.  Identify the number of transmitter mix combinations based on quantity of transmitters involved with the particular IM product frequency.

d.  Calculate the IM product power level created in each transmitter combination.

e.  Calculate the re-radiated, transmitter-produced IM product’s power level.

f.  Calculate the transmitter-produced IM product power level at the affected receiver input circuitry considering antenna configurations, transmission line losses, filter loss and other associated gains and losses.

g.  Determine if the transmitter-produced IM product power level is below the receiver’s 12dB SINAD ratio or 12 dB Carrier-to-Interference ratio.

h.  Calculate the receiver-produced IM product power level considering the transmitters radiated power level, antenna configurations, transmission line loss, filter loss and other associated gains and losses.

i.  Determine if the receiver-produced IM product power level is below the receiver’s 12 dB SINAD ratio or 12 dB Carrier-to-Interference ratio.

5.  Final Analysis

Upon completion of the interference analysis, the RF communications engineer must review the reports and determine what radio systems need additional isolation and what is required to prevent or reduce the interference to an acceptable level.  If an acceptable solution is not found, then alternative sites and/or frequency assignments should be considered.

There are generally three methods used to obtain the attenuation (isolation) required between transmitters and receivers to prevent excessive degradation of desired signals.  They include (1) adjustment of the antenna positions, both horizontally and vertically, (2) change in radiation patterns, and (3) the addition of external filters or duplexers to increase the isolation.  Sometimes combinations of these are required.

B.  Near-Far Scenario of Interference

This scenario, in addition to "C" below, must be considered when a commercial carrier is proposing to co-locate their wireless system on a structure where NO County systems are present.  This problem has been developing for the last several years and primarily impacts the public safety systems in the 800 Mhz bands (851/806 and 866/821 Mhz) from other in-band carriers such as ESMR, A and B band cellular carriers.  The problem is one of direct receiver degradation from multiple, high-intensity signals from high-density cellular deployments that are characterized by a large number of channels per sector, low antenna heights with high null-fill designs, operating frequencies in close proximity to the public safety channels, and limited band-filtering of transmitters.

For in-band operators, it is necessary to execute an Intermodulation analysis from the carrier’s transmitter frequencies to the public safety agency’s receiver frequencies to determine if there are combinations that will fall on or near the receiver channels.  The resulting intermod levels should be calculated to determine if they will cause receiver degradation.

Even in IM-free conditions, strong transmitter levels resulting from excessive antenna gain or down-tilt may cause receiver desensitization.  To determine if these high levels exist, a plot of the resulting transmitter levels in a radial from 0-800 ft from the transmitter site should be provided.  Any peculiar circumstances at the proposed site that could contribute to the exposure to interference should be identified and taken into account with the signal level calculations.  Such contributions would include geographical factors that physically place the receiver in the main lobe of the antennas such as nearby natural elevations, highway overpasses, nearby commercial buildings, etc.

Post-Construction Testing

Post-construction interference testing may be required to verify that engineered solutions for calculated degradation or interference predictions provide satisfactory results.

C.  Obstruction to Microwave Paths

This scenario, addition to "B" above, must be considered when a commercial carrier is proposing to co-locate their wireless system on a structure where NO County systems are present.  Although rare, a potential blockage can occur between two county communications sites if a carrier builds a new structure within the microwave path.  To ensure that this does not happen a plot should be provided that shows the proposed structure’s proximity to a straight line drawn between the closest two microwave sites.  If the proposed construction is greater than 500 ft from the path centerline, there is no need for further work.  Usually an electronic GIS plot or a simple plot drawn on a USGS topo map is sufficient. However, if the proposed tower is closer than 500 ft, a certified survey is required of all three locations to confirm the accuracy of the plot.

II.  Aeronautical Study

Contrary to popular belief, less than 200 ft is not the only criteria to determine if a 7460  submission to the FAA is required.  In addition, the FAA database does not include proposed changes to local airports or proposed expansions until they are certified by the FAA so ASAC reports and the FCC’s TOWAIR analysis tool may not be accurate.  There have been two incidents in Maryland, one in Calvert County and one in Charles County, where the county review identified an obstruction that would have been approved under the current industry assumption that towers less than 200 ft do not need to be submitted to the FAA.

To eliminate this potential conflict, it is recommended that any structure that is proposed within 3 miles of the center of the runway of any airport facility should be reviewed by the MAA.  The MAA maintains all the current information for the expansion and modifications to these airports. The MAA has committed to the counties that they will respond within 48 hours and a relatively simple memo with the minimum information about the proposed site (height, location, AMSL) is all that is required. Contact is Bruce Mundie at 410-859-7064.

III. RF Radiation Analysis

This analysis is relatively simple for the sole-carrier scenario since all the pertinent data is readily available.  If the structure has multiple transmitters on it, obtaining the necessary technical information may be more difficult.  The study is a standard Radiation Study compliant with FCC OET 65 to confirm that the composite transmitter levels radiating from the site will not exceed the absorption rates for occupational and general public categories. These studies are generally very conservative in nature and will reflect a worst-case scenario.

This study will need to be customized to take into account peculiar circumstances in close proximity of the site.  In the event that the calculations approach the limits, a more detailed analysis will be required to verify compliance.

IV.  Other Requirements

A structural load analysis is required, sealed by a Maryland Professional Engineer, that demonstrates the structure is capable of supporting the proposed antenna system load.  The analysis should be compliant with the current version of EIA/TIA-222 standard.

The County Ordinance requires other information associated with the proposed construction.  It requires engineering coverage maps to be submitted with the application that shows the composite coverage of the carrier within the county, the coverage prediction for the proposed site, and the new composite coverage map with the new site integrated into the overall coverage.  The carrier should explain the necessity of the site, whether for coverage or capacity.  All other reasonable co-location alternatives must also be investigated and determined not to accommodate the applicant’s needs.  This should include all towers, monopoles and water tanks.

For co-locations on existing structures, as long as the proposed antennas do not increase the overall height of the structure, an aeronautical analysis is not required. 

V.  Calvert County Communications Systems

Existing 800 Mhz System

The existing system consists of five tx/rx sites operating in the 866-869/821-824 Mhz band.  The typical transmitter is 100W output and 3 dB combining loss. The antenna systems are standard Celwave Bogner BMR12H 12/15.4 dB gain whip style antennas.  The transmitters and receivers are operating on separate transmission systems.

Frequencies

Transmitter Configuration

All transmitters are configured into one 5-chl tuned cavity combiner configuration similar to Celwave WJD-860-10 with 100W input and approximately 50W output (3 dB insertion loss).  The transmission line is 1-5/8” coax with the antenna specified. Transmitters are standard 25kHz wide with deviations up to 5 kHz.

Receiver Configuration

All receiver systems consists of a high gain antenna,  tower-top low noise amplifier, 1-1/4” coax, and the multi-coupler unit.  The system is similar to Celwave RMS-800-12A.