Prediction of AM Broadcast Field Strengths Radio Station KDKO, 1510 khz, Littleton, CO Day Pattern US West Tower DEN-118. September 15, 1997

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1 Prediction of AM Broadcast Field Strengths Radio Station KDKO, 1510 khz, Littleton, CO Day Pattern US West Tower DEN-118 September 15, 1997 Prepared by: Jay M. Jacobsmeyer, P.E. Pericle Communications Company 6180 Lehman Drive, Suite 201 Colorado Springs, CO (719) Fax: (719) For: US West Communications, Inc Grant Street Thornton, CO US West Project Manager: Don Doggett

2 Prediction of AM Broadcast Field Strengths Radio Station KDKO, 1510 khz, Littleton, CO Day Pattern US West Tower DEN-118 Summary Depending on their location and height, steel towers can adversely affect the antenna pattern of an AM broadcast station. US West Communications plans to install a PCS tower in the vicinity of AM radio station KDKO AM-1510, Littleton, CO. The purpose of this study is to employ computer models to determine the effect of the proposed tower on the AM station antenna pattern. Our desktop study shows that the US West tower does not measurably affect the pattern of the KDKO antenna array. US West will perform field strength measurements at the station s monitor points before and after PCS tower construction to verify these results. 1.0 Introduction Tower structures in the vicinity of AM broadcast towers can alter the AM antenna pattern. The FCC requires that wireless service providers notify the AM station if construction will occur within 1 kilometer of a non-directional station and 3 kilometers of a directional station. The wireless service provider must show through measurements that the tower does not affect the pattern of the AM station. If the pattern is affected by the tower, the service provider must detune the tower to bring the AM pattern back to its original specification. 1 This study was conducted for radio station KDKO-AM, Littleton, CO. The station has a directional daytime pattern and a directional nighttime pattern. The licensed frequency is 1510 khz and the day and night effective radiated powers (ERP) are 10 kw and 1.3 kw, respectively. The US West PCS tower is a monopole 78 feet high. The PCS tower is located 2.1 kilometers from the KDKO AM antenna array. The US West designator for this tower is DEN-118. Relevant tower and radio station data are listed in Table 1. 1 See FCC Part , Disturbance of AM Broadcast Station Antenna Patterns. Note that PCS operators are governed by Part 24 which has no equivalent rule. However, it is good practice to voluntarily meet the requirements of Part

3 Table 1 - Tower & Broadcaster Information AM Station Call Sign AM Station Frequency AM Station Day ERP AM Station Night ERP AM Tower Coordinates (NAD 83) PCS Tower Coordinates (NAD 83) Distance from AM to PCS KDKO 1510 khz 10 kw 1.3 kw N W N W 2.1 km Bearing, AM to PCS 2.6 Height of PCS Tower Approach To conduct this study, we used a commercial software program, MININEC Broadcast Professional. MININEC uses the method of moments technique to model both the AM antenna array and the PCS tower [1], [2]. The program computes the AM field strength in one-degree azimuth increments. The program assumes a perfectly conducting ground and computes the antenna pattern for an elevation angle of zero degrees (ground level). AM towers are modeled as thin, straight wires with seven segments per tower. Tower widths are approximately 1 meter. Current magnitudes and phases are taken from the FCC license theoretical specifications. When a station has unused towers for day or night patterns, the unused towers are shorted to ground. 3.0 Results A polar plot of the predicted KDKO pattern before and after construction is shown in Figure 1 on the next page. The maximum difference in the two patterns is db. 4.0 Conclusions Because of its low height (relative to the AM wavelength) and distance from the AM antenna array, the proposed tower should not cause a measurable change to the KDKO AM-1510 antenna pattern. 5.0 References [1] J. W. Rockway and J. C. Logan, MININEC Broadcast Professional for Windows, EM Scientific, ISBN [2] W. L. Stutzman and G. A. Thiele, Antenna Theory and Design, Wiley,

4 KDKO Before Construction (Day) KDKO After Construction (Day) Figure 1 - Before and After Day Antenna Patterns for KDKO AM-1510 (Radius in db, Angle in degrees from True North) 4

5 6.0 Engineer s Statement This study was conducted by me or under my direct supervision. All representations contained herein are true to the best of my knowledge. I am a radio engineer with over sixteen years experience. I hold a Bachelor of Science degree in Electrical Engineering from Virginia Tech and a Master of Science degree in Electrical Engineering from Cornell University. I am a corporate officer and stockholder of Pericle Communications Company and a Registered Professional Engineer in the State of Colorado. Signed on September 15, original signed - Jay M. Jacobsmeyer, P.E. Chief Technical Officer Pericle Communications Company 5

6 US West Communications: 3 copies KDKO: 1 copy Distribution

ENGINEERING REPORT: ANALYSIS OF TILLAMOOK PEOPLE S UTILITY DISTRICT PROPOSED TRANSMISSION LINE EFFECTS ON THE DIRECTIONAL ANTENNA PATTERN OF KTIL

ENGINEERING REPORT: ANALYSIS OF TILLAMOOK PEOPLE S UTILITY DISTRICT PROPOSED TRANSMISSION LINE EFFECTS ON THE DIRECTIONAL ANTENNA PATTERN OF KTIL HATFIELD & DAWSON BENJAMIN F. DAWSON III, PE CONSULTING ELECTRICAL ENGINEERS TELEPHONE (206) 783-9151 THOMAS M. ECKELS, PE FACSIMILE (206) 789-9834 9500 GREENWOOD AVE. N. STEPHEN S. LOCKWOOD, PE E-MAIL