Embedded printed edge—balun antenna system and method of operation thereof
An antenna module having a side-edge balance-to-unbalance (BALUN). The antenna module may include a flexible substrate with one or more layers that may be configured to receive one first and second conductive patterns, the substrate may have opposed first and second ends which may define a longitudinal length and/or opposed side edges situated between the first and second ends. The first conductive pattern may form an antenna loop situated adjacent to the first end of the flexible substrate and be suitable for transmitting or receiving signals at one or more frequencies. The second conductive pattern may form at least part of the BALUN and may include one or more of a center portion, side portions which may extend from the center portion at opposite sides of the center portion, and electrically neutral slots situated between a corresponding side portion and the center portion.
1. An antenna apparatus for a mobile station (MS), the antenna apparatus comprising:
a flexible substrate portion comprising one or more layers and having first and second ends defining a longitudinal length thereof, the substrate portion comprising a first portion situated adjacent to the first end and a second portion situated adjacent to the second end;
a coil antenna configured to inductively transmit or receive radio frequency (RF) signals for communication with a radio-frequency identification (RFID) device and disposed on one or more of the one or more flexible layers of the substrate portion in the first portion of the substrate portion; and
a second conductive pattern configured to be coupled to a ground plane of the MS and disposed in the second portion of the substrate portion, the second conductive pattern being further configured to form a side-edge (SE) balance-to-unbalance (BALUN) which controls impedance in the second conductive pattern, wherein the second conductive pattern has a center portion of varying width, side portions extending from the center portion and located on opposite sides of the center portion, and electrically neutral slots situated between a corresponding side portion and the center portion.
2. The apparatus of claim 1 , wherein the slots have a length that is approximately equal to λ/4, where λ is a wavelength of a band of the RF signals corresponding with a frequency band of an antenna of the MS.
3. The apparatus of claim 1 , further comprising a control portion configured to process signals received from the coil antenna or process signals for transmission by the coil antenna.
4. The apparatus of claim 1 , further comprising one or more folds situated between the first and second ends of the substrate so as to change an operating frequency band of the antenna apparatus.
5. The apparatus of claim 1 , further comprising a connector portion to couple the second conductive pattern to the ground plane of the MS.
6. A method of forming an antenna apparatus for a mobile station (MS), the method comprising acts of:
forming a flexible substrate portion comprising one or more layers and having first and second ends defining a longitudinal length and comprising first and second portions situated adjacent to the first and second ends, respectively;
forming a coil antenna configured to inductively transmit or receive radio frequency (RF) signals for communication with a radio-frequency identification (RFID) device and disposed on one or more of the one or more flexible layers of the first portion of the substrate portion in the first portion of the substrate portion; and
forming a second conductive pattern configured to be coupled to a ground plane of the MS and disposed in the second portion of the substrate portion, the second conductive pattern being further configured to form a side-edge (SE) balance-to-unbalance (BALUN) which controls impedance in the second conductive pattern, wherein the second conductive pattern is formed with a center portion of varying width, side portions extending from the center portion and located on opposite sides of the center portion, and electrically neutral slots situated between a corresponding side portion and the center portion.
7. The method of claim 6 , further comprising an act of setting a length of one or more of the slots to approximately λ/4, where λ is the wavelength of a band of the RF signals corresponding with a frequency band of an antenna of the MS.
8. The method of claim 6 , further comprising an act of forming a control portion configured to process signals received from the coil antenna or process signals for transmission by the coil antenna.
9. The method of claim 6 , further comprising an act of folding the substrate at one or more locations between the first and second ends of the substrate so as to change a frequency band of the antenna apparatus.
10. The method of claim 6 , further comprising an act of attaching a connector portion configured to couple the second conductive pattern to the ground plane of the MS.
11. The apparatus of claim 1 , wherein each side portion of the side portions extends along a portion of an adjacent side edge of the opposed side edges of the substrate.
12. The apparatus of claim 1 , further comprising an opening in the substrate situated within an area situated within a loop of the antenna loop.
13. The apparatus of claim 1 , wherein a length of one or more of the center portion, side portions, and electrically neutral slots are adjusted to change a conductance of the center portion in one or more locations.