W6PO

FCC Requirements for EME Tests Conducted by W6PO

Federal Communications Commission

Washington DC June 24, 1975

Mr.  Bob Sutherland

EIMAC

301 Industrial Way

San Carlos, CA 94070

Dear Mr. Sutherland:

We have determined your request to operate your Amateur station with a peak power output of up to 2500 watts for the purposes of experimentation with earth-moon-earth (EME) communications to be within the basis and purpose of the Amateur Radio Service. We also agree that a waiver of the power rule is justified for your EME experiments, since the signal loss to the moon is great and it is difficult to construct an antenna with enough gain to adequately overcome these losses. For these reasons we hereby waive Section 97.67(a) of the Commission's Rules to permit operation of station W6PO subject to the following conditions:

(1) An accurate log of station operation must be generated and maintained with your station records. The log must include the dates and times of each transmission, call signs of contacts, types of emission used, and frequency of operation.

(2) Reports detailing the operation, an analysis of the results, and a sampling of the station logs must be submitted to the Amateur and Citizens Division every 90 days during the term of this authorization.

(3) This waiver applies only to EME experiments and communications, and is not applicable to non-EME transmissions.

(4) The maximum peak output power authorized by this waiver is 2500 watts in CW and SSB modes.

(5) This waiver expires January 1, 1976 and may be revoked by the Commission at any time.

Sincerely yours,

Charles A. Higginbotham

Chief, Safety and Special Radio Services Bureau

Permission to operate at 2500 watts for EME experiments

This request is for temporary permission to operate a 144 MHz amateur transmitter with a peak power output up to 2500 watts on CW and SSB modes. Transmissions will be confined to the EME (earth-moon-earth, or moonbounce) mode.

A summary is enclosed of my equipment and experiments over the past few years using this mode of communication at the 1000 watt average power input level. Also enclosed is a series of EME notes I have compiled and mailed to over 300 VHF enthusiasts to help them learn about this fascinating method of amateur radio communication. A photograph of my present 144 MHz moonbounce antenna installation is also enclosed.

The moon is approximately 2160 miles in diameter and orbits the earth at a distance that varies from 221,463 to 252,710 miles. The reflection coefficient of the moon is 7%, 93% of the energy that strikes the moon being absorbed. The re-radiated signal is mainly diffused through space as the earth, as viewed from the moon, subtends an angle of only 2 degrees.

The VHF signal that returns to earth is spread over a surface area of about 98,470,000 square miles. Of this area, only a very small portion is taken up by the receiving antenna. Thus, only a small fraction of the transmitted signal in an EME circuit is picked up by the receiving antenna. This problem has challenged the ability of many of the world's most skilled VHF amateurs.

Under the best of conditions, using the maximum legal power, the most sensitive receiver and the largest possible antenna array, two-way EME communication is a marginal operation. A boost in the EME circuit by 3 t0 6 decibels would improve chances of communication immensely and raise the level of interest among amateurs who do not have the time, space and money to erect the large antenna array necessary for effective EME communication. ... continue..