Miniature Antenna: Results and Proposed Work March 2008

Outline 916 MHz antenna prototypes and results 2.2 GHz, 2.4 GHz antenna prototypes and results 433 MHz antenna prototypes and results Proposed New Research

916 MHz antenna, prototype and test results The volume of the antenna with its ground plane is λ  0.06 λ  λ, where λ = mm for 916 MHz antennas. Simulation and Measurement of S11

916 MHz antenna, Gain measurements Half wave dipoles 916 MHz FICA Half wave dipoles

S11 of 2.2 GHz & 2.45 GHz FICA 2.2 GHz FICA Bandwidth = 14 MHz 2.45 GHz FICA Bandwidth = 3 MHz 2.2GHz FICA: 98% available power transmitted 2.45GHz FICA: 92% available power transmitted Total volume including ground plane: 0.09 λ x 0.09 λ x λ λ = GHz λ = GHz

2.2 GHz FICA Gain Test (II) Calibrate using ½ wave dipole Difference between FICA and ½ dipole is -7dB; Polarization demonstrates functionality 0 Half wave dipole 68 mm 0.09 λ x 0.09 λ x λ 12 mm x 12 mm x 3.5 mm

433 MHz Dielectric Loaded Miniature Antenna Results 77.2mm 25.4mm At 433 MHz, λ=693mm. This antenna can work with a PCB board of 0.11λ x 0.037λ Initial test: -5dB Bandwidth is 8 MHz Further design needed for 10MHz bandwidth BW=8MHz

Commercial Chip Antennas (Antenna Factors, Co.) need a ground plane to function properly λ/2.98 λ/3.64 λ/4.68 λ/8 λ/ λ/8.84 SMA fed through a hole λ= cm ( 916 MHz ) Antenna 1~4, commercial chip antenna. Antenna 5: Our FICA antenna

FICA Outperforms Commercial 1.Antenna 1-4 are commercial antennas. Antenna 5 is our FICA. 2.Antenna 1 is the exact design given by spec sheet, 3.Antennas 1-3: The feeding cable is along the same direction as the feeding line, which helps antenna radiation, effectively increasing antenna size. 4.To eliminate this effect, feeding line is perpendicular to the ground plane. This was done for Antenna 4, notice enormous performance drop. 5.Our FICA (Antenna 5) has substantially better performance than commercial antennas, especially with when feed is not part of the system (4) where the improvement is by more than 23dB (200 times).

Proposed Research for Ultra-Small Antennas Task I: Design of Helical (FICA) Style Ultra-Small Antenna for Requested Specifications (400MHz resonance, 10MHz BW) Ultimate optimization goal: –Maximum achievable bandwidth (10 MHz or more Bandwidth at 400 MHz with10 dB return loss ) –minimum antenna volume (2 parts) Part1: the component which we called “antenna”, Part2: the “virtual or image antenna”-----ground plane (ground plane will be smaller than the current prototype at 400 MHz) –highest gain (-1 to -2 dBi) –highest achievable efficiency (40%<efficiency<60%)

Proposed Research for Ultra-Small Antennas: Realize Design Goals These design goals will be realized with a synergistic approach using experiment and theory: We will fabricate and test designs We will use finite element (HFSS) simulation to help guide experimental program. We will optimize the following parameters for FICA: Determine helix shapes for wire antenna families (i.e. FICA): pitch, leaning angle, cross-section area of coils, helix length, tapping point. Determine geometry of ground plane: ground plane size, feeding positions and FICA position on the ground plane. Optimize dielectric block: Use dielectric to increase capacitance to ground, not the intercoil capacitance of FICA to minimize the coil length

Proposed Research for Ultra-Small Antennas We also propose to develop circuit models of FICA for antenna-RF circuit co- design, which will maximize performance on system level. For example, for a FICA at 916 MHz (Fig a), we developed an equivaleng circuit to represent the antenna’s impedance matching, radiation resistance, and resonance. The circuit may look like the one in Fig. b. With the help of circuit b, we could optimize system gain, and sensitivity for transceivers. a b

Proposed Research for Ultra-Small Antennas Testing plan: –Will have access to a world class anechoic camber at the FDA White Oaks Facility –Antenna measurements at the FDA will be very accurate and help evaluate with precision the gain performance of the various designs. –We will regularly compare our antenna prototypes with commercially available antennas. –Comparisons will require building test platforms for commercial antennas, as well as our own.