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Correct Mobile Antenna Placement

The Larsen Company, manufacturer of quality mobile and other antennas, publishes an antenna location information sheet in their product catalog. They consider ground plane availability, the antenna electrical length and the radiation pattern of each design.Each antenna type (1/4 wave, 1/2 wave, 5/8, etc.) has a very specific radiating pattern to be considered when selecting a mobile antenna.

Larsen notes that "the signal radiating from a 1/ 4 wave antenna is directed more vertically, thus making it ideal in urban environments where buildings might obstruct the signal. The design of a 5dB collinear mobile antenna is designed to direct the signal more towards the horizon. This type of antenna is ideal for geographically fiat regions where the signal coverage is sparse."

Using a standard automobile, there are five possible general locations for mounting and antenna: the roof, front fender, rear fender, trunk and rear (or other) window glass. The center of the roof is always the best location for a mobile antenna. Using it as reference, here is a comparison for VHF (2M) of the other locations for different antenna mounts:

Roof center (permanent) 0.0dB Hood corner (magnetic mount) -2.4dB
Roof center (magnetic mount) -0.2dB
Roof corner (magnetic mount) -0.2dB Trunk center permanent) -2.1dB
Trunk center (magnetic mount) -2.8dB
On-Glass (upper window) -0.5dB Trunk lip (center) mount -2.8dB
On-Glass (mid part window) -1.2dB Trunk comer (magnetic mount) -3.4dB
On-Glass (lower window) -3.0dB

As you can see, the placement of your antenna and the way you mount it is critical. You can loose all the benefit of that "super" antenna by putting it in the wrong spot. Bob, K4HA just did a new antenna installation on his shiny new pickup. Looks like he did a good job with NO negative dB's! KE4ZEQ

PCRN Field Service Report

On Saturday, April 3, Danny K4ITL, Mike WB4TQD, and Bob K4HA made a visit to the 147.15 repeater site to troubleshoot the reduced coverage on both talkout and talkin. An earlier inspection my Mike had revealed that the SWR at the bottom end of the 800 ft transmission line was about 1.6 : 1. With 800 ft of 7/8 inch Heliax, this makes the actual SWR at the fault (assuming it's at the top end of the cable), much higher. Mike climbed the tower and about 40 minutes later he was up top (I knew he was doing that daily workout for some reason!). The jumper that went from the end of the transmission line to the pigtail on the antenna was bad. The elements had just taken their toll on it. Basically the repeater was transmitting on this little open piece of transmission line that was up there at 800 ft. That fixed the talkout coverage problem.

The talkin problem (many have noticed that portable talkin isn't what it used to be) was traced to three of the four antenna elements on the receive antenna (it's a Decibel Products DB-224) being broken. This is a fairly common failure mode with these antennas. The wind vibrates the antenna elements and over time the metal fatigues and the elements (which are made of aluminum tubing) simply break apart. Fortunately it looks like that the whole antenna won't have to come down. Replacement dipoles are being ordered from Decibel Products. They are small enough that they can be carried up and replaced with the main antenna still on the tower.

These guys deserve a big thank you for their hard work and support to keep things working at top notch efficency. Those that know Danny and Mike can appericate that they're the "Richard Petty" of repeaters.

Stock performance is NEVER good enough.... always pushing to get that last 0.5 dB out of things.

Do your part and support PCRN financially if you haven't already done so. They will apperciate it and others that use the repeater will too. Thanks and 73 Frank, KE4ZEQ

Bandwidth may be infinite, but land is not.

Here's the latest play in the wireless game.

Tower Power

By Michelle Conlin

REAL ESTATE STOCKS are in the dumps. From operators of trailer parks to collections of Class A office space, the shares of real estate companies are down 26% from September.

But one obscure corner of the real estate business, one that's only a few years old, is in a bull market: wireless towers. This bane of every neighborhood zoning czar is emerging as the hot new play. Shares of the two top publicly traded companies (see table) that own towers are up an average 52% since September.

Six wireless carriers now compete in most of the top 15 U.S. markets. It's a buyer's market. But the supply of choice transmission sites is short. With at least 92 million dropped or interrupted calls every month, demand for better wireless coverage is intense. There are now about 65,000 towers in the U.S. Carriers will need 35,000 more by 2004.

Demand for good sites is so intense that Samuel Zell's Chicago-based Equity Office Properties has seen rents for its rooftops double since 1996, to more than $1,600. In contrast, rents for the new office space below are only up 25%.

Steven Dodge sees the value in such vertical real estate. In 1995 the former lending officer at BankBoston took his American Radio Corp. public at $16.50 a share, then sold the company's 100 radio stations to CBS three years later in a deal worth $2.6 billion. For each American Radio share, Dodge's original investors got $44 in cash and one share, worth $21, of a newly created public company, American Tower.

With this new Boston-based company, Dodge kept control of the towers the stations used, figuring correctly, that he would have no problem renting antenna space on the towers to cellular phone operators. Shares now trade at $25. American Tower has 3,200 towers, more than any firm in the U.S., and it is buying and building rapidly. Dodge aims to have 10,000 by 2003.

Carriers are only too happy to sell these vertical eyesores to entrepreneurs like Dodge-and get the debt used to finance them off their balance sheets. Carriers also don't want competitors sharing their tower space. A third party can more easily rent to multiple tenants.

Bell Atlantic was the first to throw in the towel. In December it sold off its 1,427 towers to a joint venture with Crown Castle International Corp. Bell Atlantic got $380 million in cash and a 37.7% equity stake in the joint venture, worth $240 million.

Two months later Nextel followed suit by selling its 2,000 towers to privately held SpectraSite for $560 million in cash plus a 17% equity stake in the company, worth $70 million.

Where's all this cash coming from? Mostly debt. A lot of the tower outfits have debt loads of 65% of capital or more. Carrying costs are high. None of the firms is making a profit yet.

But the potential is certainly there. Towers positioned on the ground cost about $200,000 to build. Operating costs hover around $10,000 a year no matter if there's one tenant or ten. Rents run from $2,200 a month per tenant for a city like Boston down to $500 in a rural area.

American Tower's Dodge gets an average of 4.5 tenants on each of his towers in Florida. In a city, of course, he has to pay rooftop rent to a Sam Zell. Still, Dodge says that in some areas he's seeing a 40% cash-on-cash return, meaning that if he spends $200,000 on a site he will pocket $80,000-a-year over and above the minimal operating costs.

Build a hotel and you have to fluff the pillows every day. "With a tower, all you have to do is put down the weed killer and mow the grass," says SpectraSite's chief executive, Stephen Clark.

Clark not only plans to increase the number of cellular tenants on the former Nextel towers, but he also won the rights to build 1,700 more towers for Nextel over the next five years.

Expect more deals like these. Already rural affiliates of AT&T and Sprint are using the tower companies to do the building and managing for them.

Someday there will be a glut of wireless towers. But that's a few years off.

Titans of tower

Company Ticker Towers owned Revenue ($mil)* Oper income ($mil)* Acquisitions
American Tower AMT 2,633 $137 $87 Telecom's towers
Crown Castle† TWRS 2,003 6 52 Bell Atlantic's towers
Pinnacle BIGT 1,040 56 46 Mobile Media's towers
Spectra Site private 2,125 58 36 Nextel's towers
SBA private 520 27 15 Fifty-one mom-and-pops
WesTower WTW 234 11 7 Koch Indutstries' towers

*Est. 1999 pro forma U.S. operations, excludes managed towers and corporate expenses. Operating income equals net before depreciation, interest and taxes. † Excluding U.K. operations.

Feedline's April Brainteaser

A simple series DC circuit consists of a 10 volt DC source, and two resistors in series. The first resistor is a known value (5 Ohms). The value on the second resistor is missing, but someone measures the heat coming from the resistor and determines that it is dissipating 3 Watts of power. What is the value of the resistor?

Email your solutions to [email protected] The answers and the folks who correctly solved the problem will be in next months issue!

CARC Minutes - W3HL

Meeting opened at 7:34 p.m., by Pres., Charles, KE4CDI. All introduced themselves.

Treasurer's Report - The report from Will, K4IWW, was read in his absence as: Savings, $1,210.83; Checking, $1,107.78; C-O-H, $87.00; Total, $2,405.61. Dues are due at this (March) meeting.

Piedmont-Coastal Repeater Network (PCRN) - Ed, AB4S, gave no formal report, but he suggested the attendees re-read the Minutes in the February FEEDLINE. That was of the "rule" that every Amateur who uses repeaters locally, should support their own local repeater. Then, they will feel more comfortable using a repeater away from their home territory. The PCRN does a great job of keeping many repeaters across NC up and running. The labor is donated, BUT the equipment does require some monies. The suggested annual donation is: $15. The mailing address is: PCRN, P. O. Box 12734, Raleigh, NC 27605. They take checks, U.S. funds, gold and silver bullion, rare coins, bearer bonds and other negotiable securities, etc. You really have little excuse for NOT supporting PCRN.

Amateur Radio Emergency Service (ARES) - No report. (Please note that it is hurricane season, again. Sometime, somewhere, the Amateur Radio community [ARES] will be called on to assist in both major and minor disasters. It takes your willingness AND equipment that is ready to go. No time to buy batteries [from a store that may not be there anymore] or to recharge the NiCds. Check the stuff out, folks.)

South Eastern Repeater Association (SERA) - Frank, KE4ZEQ, described SERA and it's functions to the attendees. SERA's presence and influence over the years has produced the relative calm and cooperation we enjoy in the south east part of the country. If you have never been in other parts of thecountry, please understand that the repeater scene isn't as calm in most of them. Actually, "war zone" might be a more accurate description. Support SERA for your own benefit.

Bob, K4HA, is getting tee shirts with appropriate logos bragging about the great 1998 Field Day showing that CARC made. They have been custom ordered by size. The nominal cost is $10. Frank KE4ZEQ will have the shirts at the club meeting . Thanks, Bob.

Please mark June 26-27, 1999 on your calendars. THAT IS FIELD DAY WEEKEND!!!

Please mark Friday evening, July 16 and Saturday, July 17 on your calendars.


Feedline's April Brainteaser II

The Frequency Planning Problem

An imaginary Amateur Radio Frequency Coordinator has just been given a 6 MHz of spectrum for repeater use (3 MHz for Output and 3 MHz for input). He wants to decide which channel spacing would be the best. If he does 15 KHz channel spacing, he can make 200 repeater pairs out. If he does 20 KHz channel spacing, he can make 150 repeater pairs. If he uses 15 KHz channel spacing, co-channel repeaters (on the same freq), must be at least 100 miles apart and adjacent (+/- 15 KHz) channels must be at least 50 miles distant. If he uses 20 KHz channel spacing, co-channel repeaters must still be 100 miles apart, but adjacent channels only have to be 25 miles distant. If he's trying to cover a large area, (many states), which band plan will result in the best frequency utilization (channels per square mile).

If you make a mistake, you have to pay to recrystal all the repeaters! (just kidding).

Send your answers to [email protected], the answer will be in next months feedline.

6 meter DX Rocks and Roll

AA7A, VHF Reflector

Look for the 6 meter band to become a DX'ers paradise as Ned Stearns, AA7A, operates on 6 meters from Rodriguez Island. This as part of the long awaited 3B9R DXpedition operation. Ned posted on the VHF Reflector that he hoped to be on Rodriguez in grid MH10 the evening of March 31st. If all went well, he should have been fully operational on April 1st, starting with the morning contact opportunities to Japan. He says that he plans to be listening on 50.115 MHZ and will transmit on the normal 6 meter DX frequencies.

If the name Ned Stearns AA7A, sounds familiar, that's because he was a frequent guest and occasional co-host with Len Winkler, KB7LPW, of the now-defunct "Ham Radio and More" radio program. Ned plans for AA7A to be running 100 Watts to a long yagi antenna. The station will be located in the town of Port Matherin on the north central side of the island with an unobstructed view of the horizon and on to Japan and Europe. Six meter operations from the island will end on April 11th.

Stearns knows that there is little chance of working the United States on this trip. He joined the expedition to demonstrate the value of a serious six meter station. But with six meters starting to sound more like 20 and 15, who knows. We might be hearing Ned's 3B9R signal from Rodruigez Island over the next several days.

Vanity Callsign application fee to rise slightly

Later this year, the cost of applying for an amateur vanity callsign is expected to rise slightly. In a just-released Notice of Proposed Rulemaking, the FCC has proposed increasing the vanity fee to $14.20 for the 10 year term. The current vanity fee is $13. The FCC projects 6800 vanity applications in Fiscal Year 1999 for a total revenue figure of more than $96,000. The NPRM itself involves the assessment and collection of regulatory fees for Fiscal Year 1999.


Feedline is a member-supported publication of the Cary Amateur Radio Club and is published monthly. Deadline for submissions is the second Thursday of the month. Editor: Tom Klimala, KM4LB 1545 Seabrook Avenue Cary, North Carolina 27511 [email protected]