Magic tee and George Porteous

A magic T consisting of four rectangular waveguides meeting in a single three-dimensional junction

A magic tee (or magic T or hybrid tee) is a hybrid or 3 dB coupler used in microwave systems. It is an alternative to the rat-race coupler. In contrast to the rat-race, the three-dimensional structure of the magic tee makes it less readily constructed in planar technologies such as microstrip or stripline.

The magic tee was originally developed in World War II, and first published by W. A. Tyrell (of Bell Labs) in a 1947 IRE paper. Robert L. Kyhl and Bob Dicke independently created magic tees around the same time.

Contents 1 Structure 2 Operation 3 Magic 4 References


The magic tee is a combination of E and H plane tees. Arm 3 forms an H-plane tee with arms 1 and 2. Arm 4 forms an E-plane tee with arms 1 and 2. Arms 1 and 2 are sometimes called the side or collinear arms. Port 3 is called the H-plane port, and is also called the Σ port, sum port or the P-port (for "parallel"). Port 4 is the E-plane port, and is also called the Δ port, difference port, or S-port (for "series"). There is no one single established convention regarding the numbering of the ports.

To function correctly, the magic tee must incorporate an internal matching structure. This structure typically consists of a post inside the H-plane tee and an inductive iris inside the E-plane limb, though many alternative structures have been proposed. Dependence on the matching structure means that the magic tee will only work over a limited frequency band. Operation

The name magic tee is derived from the way in which power is divided among the various ports. A signal injected into the H-plane port will be divided equally between ports 1 and 2, and will be in phase. A signal injected into the E-plane port will also be divided equally between ports 1 and 2, but will be 180 degrees out of phase. If signals are fed in through ports 1 and 2, they are added at the H-plane port and subtracted at the E-plane port. Thus, with the ports numbered as shown, and to within a phase factor, the full scattering matrix for an ideal magic tee is

(the signs of the elements in the fourth row and fourth column of this matrix may be reversed, depending on the polarity assumed for port 4). Magic

If, by means of a suitable internal structure, the E-plane (difference) and H-plane (sum) ports are simultaneously matched, then by symmetry, reciprocity and conservation of energy it may be shown that the two collinear ports are also matched, and are magically isolated from each other.

The E-field of the dominant mode in each port is perpendicular to the broad wall of the waveguide. The signals in the E-plane and H-plane ports therefore have orthogonal polarizations, and so (considering the symmetry of the structure) there can be no communication between these two ports.

For a signal entering the H-plane port, a well-designed matching structure will prevent any of the power in the signal being reflected back out of the same port. As there can be no communication with the E-plane port, and again considering the symmetry of the structure, then the power in this signal must be divided equally between the two collinear ports.

Similarly for the E-plane port, if the matching structure eliminates any reflection from this port, then the power entering it must be divided equally between the two collinear ports.

Now by reciprocity, the coupling between any pair of ports is the same in either direction (the scattering matrix is symmetric). So if the H-plane port is matched, then half the power entering either one of the collinear ports will leave by the H-plane port. If the E-plane port is also matched, then half power will leave by the E-plane port. In this circumstance, there is no power 'left over' either to be reflected out of the first collinear port or to be transmitted to the other collinear port. Despite apparently being in direct communication with each other, the two collinear ports are magically isolated.

The isolation between the E-plane and H-plane ports is wide-band and is as perfect as is the symmetry of the device. The isolation between the collinear ports is however limited by the performance of the matching structure.

George Porteous and Magic tee

George Porteous, CM, MBE (April 7, 1903–February 6, 1978) was the 14th Lieutenant Governor of Saskatchewan, Canada from 1976 to 1978.

Contents 1 Early life 2 War service 3 Honours 4 Medical research 5 Bibliography 6 References 7 External links

Early life

George Porteous was born in Douglas, Lanarkshire, Scotland on 7 April 1903. His family emigrated to Canada in 1910 and he attended secondary school in Saskatoon, going on to the University of Saskatchewan, where he was awarded BA in 1927. He began working for the YMCA as boys’ work secretary in Saskatoon in 1922, later becoming an Army physical education instructor. At the outbreak of World War II he went with the 1st Canadian Division to England as a YMCA Auxiliary Service officer, returning later on to Canada to train others. War service

In 1941 Porteous was posted with the Winnipeg Grenadiers to Hong Kong, to reinforce the British garrison. The regiment arrived just in time to be overwhelmed by invading Japanese forces, and Porteous was to spend a total of 44 months in one of the notorious prisoner of war camps, where he remained until the end of the war. In due course he was decorated as an MBE, Member of the Order of the British Empire, for his outstanding contribution in maintaining prisoner morale while imprisoned. Honours

Porteous returned to Saskatoon after the war and was named executive director of the Saskatoon Community Chest. He was later awarded the Order of Canada in 1974 for dedication to community affairs, and was appointed Lieutenant-Governor of Saskatchewan, the Queen’s representative, in 3 March 1976, thus becoming that Province’s 14th Lieutenant Governor. He died in office on 6 February 1978. Medical research

An interesting insight into Porteous' experience is that from 1960 until his death in 1978 Porteous was an enthusiastic advocate of the medical benefits of niacin. Dr. Abram Hoffer had approached him to request that he recommend it to the senior citizens in the social housing development which Porteous administered. Hoffer believed large doses of niacin, up to six grams a day, could retard the development and even reverse senility, as it dilates the blood vessels, thus improving circulation.

Porteous insisted he would not recommend anything to anyone which he had not first tried himself. For six months, he took the six grams a day and then recommended it to the senior citizens without reservation. As he told the Department of Veterans Affairs doctor on his next annual visit (he was on a 100% disability pension) that he had not felt as well since before the war; he could even touch his hands together above his head, not having been able to raise them above his shoulders before the treatment. He discovered that niacin had greatly relieved the severe arthritis and insomnia that had plagued him as a result of his wartime imprisonment and systematic starvation over a four-year period. He supported the use of this vitamin for all Canadian and US ex-prisoners of war suffering from similar symptoms. Bibliography Hoffer, Abram (2008), Orthomolecular Medicine for Everyone: Megavitamin Therapeutics for Families and Physicians (Vol 2), Laguna Beach, California: Basic Health Publications, ISBN 978-1-59120-226-4 
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