We were tasked to create a portable antenna package. This antenna package needed to conform to various design specifications. Many times radio users are placed in situations where handheld to handheld communications are inhibited by physical land attributes, such as terrain, distance, and impeding structures. In order to over come these obstacles a repeater is often utilized to facilitate communication through its placement in a “high-ground” position. Situations where this type of interaction is required are often temporary and therefore a portable, inexpensive alternative repeater system is desired. Project Problem Definition

Technical Requirements Output power will be between 5 and 70 Watts. Must conform to FCC emission standards. Must simultaneously transmit and receive FM voice signals ( MHz). Coverage area is a radius of 1-2 miles. Vertically polarized and omnidirectional. The general size must be as small as possible but still effective. The unit must be lightweight. The unit must be easily transportable by two people on foot.

Antenna Design Possibilities Loop Antennas +Easy to Build (in theory) +Inexpensive and Light Materials +Conceptually Simple +Even Radiation Pattern -Complex Mathematical Analysis -Flimsy Design -Accurate construction would be complicated Dipole Antennas +Many Different Variations +Easy to Build (in theory) +Inexpensive and Light Materials +Conceptually Simple +Radiation Pattern Nulls -Most designs would be flimsy -Folded designs may be difficult to build

Chosen Antenna Design Discpole Antenna +A vertically stacked dual array could be less than 5 feet tall +Anyone can build it in an afternoon for under $20 +The discpole’s radiation pattern shows nulls above and below the discs, making vertical separation an effective means of isolating the transmit and receive antennas

Radiation patterns of 500MHz test antenna Receive Antenna (normalized to dB) Transmit Antenna (normalized to dB) These patterns are ideal for our purposes.

Radiation Pattern Ink Blot Test What do you see here?