1. A method comprising:
receiving, from a network operator, an instruction to change a setting of a polarization controller, the polarization controller one of a plurality of polarization controllers distributed within an optical network, the instruction not responsive to a detected error in a discrete optical communication, the instruction provided responsive to an indication related to a probability density function associated with a Polarization Mode Dispersion vector;
responsive to the instruction to change the setting of the polarization controller, automatically changing a first rotational speed of a birefringent plate of a plurality of birefringent plates associated with the polarization controller to orient the birefringent plate pseudo-randomly over time with respect to a predetermined axis, the first rotational speed less than about one revolution per thirty seconds, said automatically changing the rotational speed performed with respect to a second rotational speed of at least one other birefringent plate of the plurality of birefringent plates associated with the polarization controller, the second rotational speed less than about one revolution per thirty seconds,
wherein said first rotational speed is chosen according to R\u02dc10(N*T), where R is a needed number of rotations per unit time given in terms of the number of polarization controllers N, and the time period T of an Service Level Agreement to be satisfied.
2. The method of claim 1, further comprising:
placing a channel in a high availability service based upon a predetermined Polarization Mode Dispersion vector statistical parameter associated with the probability density function.
3. The method of claim 1, further comprising:
automatically changing a third rotational speed of a third birefringent plate associated with the polarization controller responsive to the probability density function associated with a Polarization Mode Dispersion vector, the third rotational speed less than about one revolution per thirty seconds.
4. The method of claim 1, further comprising:
causing a Polarization Mode Dispersion vector statistical parameter to be substantially similar for all channels associated with the optical network.
5. The method of claim 1, wherein the plurality of polarization controllers are distributed within the optical network at approximately equal distances.
6. The method of claim 1, wherein the plurality of polarization controllers are randomly distributed within the optical network.
7. The method of claim 1, wherein the probability density function approximates a Maxwellian distribution.
8. The method of claim 1, wherein the probability density function is detectably different from a Maxwellian distribution.
9. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a seventy two hour period.
10. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a forty-eight hour period.
11. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a twenty-four hour period.
12. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a twelve hour period.
13. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a six hour period.
14. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a three hour period.
15. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a one hour period.
16. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a thirty minute period.
17. The method of claim 1, wherein said automatically changing the rotational speed is adapted to change the rotational speed of the birefringent plate to a rate less than about one revolution in a one minute period.
18. A method comprising:
installing a plurality of polarization controllers within an optical network; and
programming at least one polarization controller of the plurality of polarization controllers to receive an instruction for a setting change, the instruction not responsive to a detected error in a discrete optical communication, the instruction provided responsive to an indication related to an estimated Maxwellian probability density function associated with a Polarization Mode Dispersion vector, the at least one polarization controller adapted to, responsive to the instruction to slowly automatically change a rotational speed of a birefringent plate of a plurality of birefringent plates associated with each polarization controller, each rotational speed changed to orient the birefringent plate pseudo-randomly over time with respect to a predetermined axis, each rotational speed less than about one revolution per thirty seconds;
wherein said first rotational speed is chosen according to R\u02dc10(N*T), where R is a needed number of rotations per unit time given in terms of the number of polarization controllers N, and the time period T of an Service Level Agreement to be satisfied.
19. A computer-readable medium comprising machine instructions capable of being executed by a computer for activities comprising:
receiving, from a network operator, an instruction to change a setting of a polarization controller, the polarization controller one of a plurality of polarization controllers distributed within an optical network, the instruction not responsive to a detected error in a discrete optical communication, the instruction provided responsive to an indication related to a probability density function associated with a Polarization Mode Dispersion vector;
responsive to the instruction to change the setting of the polarization controller, automatically changing a first rotational speed of a birefringent plate of a plurality of birefringent plates associated with the polarization controller to orient the birefringent plate pseudo-randomly over time with respect to a predetermined axis, the first rotational speed less than about one revolution per thirty seconds, said automatically changing the rotational speed performed with respect to a second rotational speed of at least one other birefringent plate of the plurality of birefringent plates associated with the polarization controller, the second rotational speed less than about one revolution per thirty seconds;
wherein said first rotational speed is chosen according to R\u02dc10(N*T) where R is a needed number of rotations per unit time given in terms of the number of polarization controllers N, and the time period T of an Service Level Agreement to be satisfied.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An information terminal apparatus comprising: a variable directional antenna and an information terminal unit for effecting radio communication using said variable directional antenna;
said information terminal unit having a transmittingreceiving means, and a processing means for determining a directivity of said variable directional antenna using said transmittingreceiving means;
said variable directional antenna having a control means for controlling said directivity of said variable directional antenna in accordance with directivity data determined by said processing means of said information terminal unit;
said processing means further comprising: a first means for obtaining a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna during a first period; a second means for determining an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data; and a third means for setting a directivity of said variable directional antenna, based on a result obtained by said second means during said first period; and
said information terminal unit further comprising a circuit means for performing a packet communication,
wherein said information terminal unit performs said packet communication by fixing said directivity of said variable directional antenna to said optimum directivity, during a second period which is different from said first period, and
said information terminal unit does not perform said packet communication during said first period.
2. The information terminal apparatus according to claim 1, wherein said first period is provided immediately before said information terminal unit transmitting or receiving a packet.
3. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
said information terminal unit having a transmittingreceiving means, and a processing means for determining a directivity of said variable directional antenna using said transmittingreceiving means;
said variable directional antenna having a control means for controlling said directivity of said variable directional antenna in accordance with directivity data determined by said processing means of said information terminal unit;
said processing means further comprising: a first means for obtaining a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna; a second means for determining an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data; and a third means for setting a directivity of said variable directional antenna, based on a result obtained by said second means;
said variable directional antenna comprising:
a main antenna element that is fed from said transmittingreceiving means of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a variable phase shifter circuit for controlling a reactance component of said sub-antenna element; and
directivity control data, stored in a memory, to control said reactance component of said sub-antenna element; and
said control means of said variable directional antenna having:
a data receiving means for receiving directivity data from said information terminal unit;
a data readout means for reading out said directivity control data from said memory, based on said received directivity data; and
a DA converter for converting said directivity control data into an analog voltage;
thereby said control means controls said reactance component of said variable phase shifter circuit in accordance with said analog voltage output from said DA converter.
4. The information terminal apparatus according to claim 3, wherein said variable phase shifter circuit having a varactor diode connected to said sub-antenna element.
5. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
said information terminal unit having a transmittingreceiving means, and a processing means for determining a directivity of said variable directional antenna using said transmittingreceiving a means;
said variable directional antenna having a control means for controlling said directivity of said variable directional antenna in accordance with directivity data determined by said processing means of said information terminal unit;
said processing means further comprising: a first means for obtaining a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna; a second means for determining an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data; and a third means for setting a directivity of said variable directional antenna, based on a result obtained by said second means;
said variable directional antenna comprising:
a main antenna element that is fed from said transmittingreceiving means of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element; and
a plurality of switching means for controlling a connection between said strip line and said stubs, respectively, and
said control means of said variable directional antenna having:
a data receiving means for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data;
thereby said control means controls said reactance component of said sub antenna in accordance with an output signal of said decoder.
6. The information terminal apparatus according to claim 5, wherein said switching means is either a GaAs FET or a PIN diode.
7. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
said information terminal unit having a transmittingreceiving means, and a processing means for determining a directivity of said variable directional antenna using said transmittingreceiving means;
said variable directional antenna having a control means for controlling said directivity of said variable directional antenna in accordance with directivity data determined by said processing means of said information terminal unit;
said processing means further comprising: a first means for obtaining a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna; a second means for determining an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data; and a third means for setting a directivity of said variable directional antenna, based on a result obtained by said second means;
said variable directional antenna comprising:
a main antenna element that is fed from said transmittingreceiving means of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element; and
a plurality of switching means for connecting between different positions of said strip line and the ground, so as to change said reactance component of said sub-antenna element; and said control means of said variable directional antenna having;
a data receiving means for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data;
thereby said control means controls said reactance component of said sub antenna in accordance with an output signal of said decoder.
8. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
said information terminal unit having a transmittingreceiving means, and a processing means for determining a directivity of said variable directional antenna using said transmittingreceiving means;
said variable directional antenna having a control means for controlling said directivity of said variable directional antenna in accordance with directivity data determined by said processing means of said information terminal unit;
said processing means further comprising: a first means for obtaining a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna; a second means for determining an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data; and a third means for setting a directivity of said variable directional antenna, based on a result obtained by said second means;
said variable directional antenna comprising:
a main antenna element that is fed from said transmittingreceiving means of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element; and
a plurality of switching means for controlling a connection between said stub and said strip line or said stub and the ground so as to be a short stub or an open stub; and
said control means of said variable directional antenna having;
a data receiving means for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data;
thereby said control means controls said reactance component of said sub antenna in accordance with an output signal of said decoder.
9. A variable directional antenna comprising:
a main antenna element that is fed from a transmittingreceiving means of a information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a variable phase shifter circuit for controlling a reactance component of said sub-antenna element;
directivity control data, stored in a memory, to control said reactance component of said sub-antenna element; and
a control means for controlling said variable phase shifter circuit;
said control means having:
a data receiving means for receiving directivity data from said information terminal unit;
a data readout means for reading out said directivity control data from said memory, based on said received directivity data; and
a DA converter for converting said directivity control data into an analog voltage;
thereby said control means controls said reactance component of said variable phase shifter circuit in accordance with said analog voltage output from said DA converter.
10. The variable directional antenna according to claim 9, wherein said variable phase shifter circuit having a varactor diode connected to said sub-antenna element.
11. A variable directional antenna comprising:
a main antenna element that is fed from a transmittingreceiving means of a information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element;
a plurality of switching means for controlling a connection between said strip line and said stubs, respectively; and
a control means for controlling said switching means;
said control means having:
a data receiving means for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data;
thereby said control means controls said reactance component of said sub antenna in accordance with an output signal of said decoder.
12. The variable directional antenna according to claim 11, wherein said switching means is either a GaAs FET or a PIN diode.
13. A variable directional antenna comprising:
a main antenna element that is fed from a transmittingreceiving means of a information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of switching means for connecting between different positions of said strip line and the ground, so as to change said reactance component of said sub-antenna element; and
a control means for controlling said switching means;
said control means having:
a data receiving means for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data;
thereby said control means controls said reactance component of said sub antenna in accordance with an output signal of said decoder.
14. A variable directional antenna comprising:
a main antenna element that is fed from a transmittingreceiving means of a information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element;
a plurality of switching means for controlling a connection between said stub and said strip line or said stub and the ground so as to be a short stub or an open stub; and
a control means for controlling said switching means; said control means having:
a data receiving means for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data;
thereby said control means controls said reactance component of said sub antenna in accordance with an output signal of said decoder.
15. An information terminal apparatus comprising: a variable directional antenna and an information terminal unit for effecting radio communication using said variable directional antenna;
wherein
said information terminal unit comprises a transmitterreceiver;
said information terminal unit is configure to determine a directivity of said variable directional antenna using said transmitterreceiver;
said variable directional antenna is configured to control said directivity of said variable directional antenna in accordance with directivity data determined by said information terminal unit; and
said information terminal unit is configured to obtain a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna during a first time period, to determine an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data, and to set a directivity of said variable directional antenna, based on said determined optimum directivity during said first period,
wherein said information terminal unit performs a packet communication by fixing said directivity of said variable directional antenna to said optimum directivity, during a second period which is different from said first period, and
said information terminal unit does not perform said packet communication during said first period.
16. The information terminal apparatus according to claim 15, wherein said first period is provided immediately before said information terminal unit transmitting or receiving a packet.
17. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
wherein
said information terminal unit comprises a transmitterreceiver;
said information terminal unit is configure to determine a directivity of said variable directional antenna using said transmitterreceiver;
said variable directional antenna is configured to control said directivity of said variable directional antenna in accordance with directivity data determined by said information terminal unit; and
said information terminal unit is configured to obtain a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna, to determine an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data, and to set a directivity of said variable directional antenna, based on said determined optimum directivity,
wherein said variable directional antenna comprises:
a main antenna element that is fed from said transmitterreceiver of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a variable phase shifter circuit for controlling a reactance component of said sub-antenna element;
a memory for storing directivity control data to control said reactance component of said sub-antenna element;
a data input for receiving directivity data from said information terminal unit;
a data reader for reading out said directivity control data from said memory, based on said received directivity data; and
a DA converter for converting said directivity control data into an analog voltage,
said reactance component of said variable phase shifter circuit being controlled in accordance with said analog voltage output from said DA converter.
18. The information terminal apparatus according to claim 17, wherein said variable phase shifter circuit comprises a varactor diode connected to said sub-antenna element.
19. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
wherein
said information terminal unit comprises a transmitterreceiver;
said information terminal unit is configure to determine a directivity of said variable directional antenna using said transmitterreceiver;
said variable directional antenna is configured to control said directivity of said variable directional antenna in accordance with directivity data determined by said information terminal unit; and
said information terminal unit is configured to obtain a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna, to determine an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data, and to set a directivity of said variable directional antenna, based on said determined optimum directivity,
wherein said variable directional antenna comprises:
a main antenna element that is fed from said transmitterreceiver of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element;
a plurality of switches for controlling a connection between said strip line and said stubs, respectively;
a data input for receiving directivity data from said information terminal unit; and
a decoder for controlling said switches, based on said received directivity data,
said reactance component of said sub antenna being controlled in accordance with an output signal of said decoder.
20. The information terminal apparatus according to claim 19, wherein at least one of said switches is either a GaAs FET or a PIN diode.
21. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
wherein
said information terminal unit comprises a transmitterreceiver;
said information terminal unit is configure to determine a directivity of said variable directional antenna using said transmitterreceiver;
said variable directional antenna is configured to control said directivity of said variable directional antenna in accordance with directivity data determined by said information terminal unit; and
said information terminal unit is configured to obtain a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna, to determine an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data, and to set a directivity of said variable directional antenna, based on said determined optimum directivity,
wherein said variable directional antenna comprises:
a main antenna element that is fed from said transmitterreceiver of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of switches for connecting between different positions of said strip line and the ground, so as to change said reactance component of said sub-antenna element;
a data input for receiving directivity data from said information terminal unit; and
a decoder for controlling said switches, based on said received directivity data,
said reactance component of said sub antenna being controlled in accordance with an output signal of said decoder.
22. An information terminal apparatus comprising: a variable directional antenna; and an information terminal unit for effecting radio communication using said variable directional antenna;
wherein
said information terminal unit comprises a transmitterreceiver;
said information terminal unit is configure to determine a directivity of said variable directional antenna using said transmitterreceiver;
said variable directional antenna is configured to control said directivity of said variable directional antenna in accordance with directivity data determined by said information terminal unit; and
said information terminal unit is configured to obtain a directivity characteristics data of said variable directional antenna by sequentially sending a plurality of directivity data to said variable directional antenna, to determine an optimum directivity with the best receiving condition in accordance with obtained directivity characteristics data, and to set a directivity of said variable directional antenna, based on said determined optimum directivity,
wherein said variable directional antenna comprises:
a main antenna element that is fed from said transmitterreceiver of said information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element;
a plurality of switches for controlling a connection between said stub and said strip line or said stub and the ground so as to be a short stub or an open stub;
a data input for receiving directivity data from said information terminal unit; and
a decoder for controlling said switches, based on said received directivity data,
said reactance component of said sub antenna being controlled in accordance with an output signal of said decoder.
23. A variable directional antenna comprising:
a main antenna element that is fed from a transmitterreceiver of an information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a variable phase shifter circuit for controlling a reactance component of said sub-antenna element;
a memory for storing a directivity control data to control said reactance component of said sub-antenna element; and
a data input for receiving directivity data from said information terminal unit;
a data reader for reading out said directivity control data from said memory, based on said received directivity data; and
a DA converter for converting said directivity control data into an analog voltage,
wherein said reactance component of said variable phase shifter circuit is controlled in accordance with said analog voltage output from said DA converter.
24. The variable directional antenna according to claim 23, wherein said variable phase shifter circuit comprises a varactor diode connected to said sub-antenna element.
25. A variable directional antenna comprising:
a main antenna element that is fed from a transmitterreceiver of an information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element;
a plurality of switches for controlling a connection between said strip line and said stubs, respectively;
a data input for receiving directivity data from said information terminal unit; and
a decoder for controlling said switches, based on said received directivity data,
wherein said reactance component of said sub antenna is controlled in accordance with an output signal of said decoder.
26. The variable directional antenna according to claim 25, wherein at least one of said switches is either a GaAs FET or a PIN diode.
27. A variable directional antenna comprising:
a main antenna element that is fed from a transmitterreceiver of an information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of switches for connecting between different positions of said strip line and the ground, so as to change said reactance component of said sub-antenna element;
a data input for receiving directivity data from said information terminal unit; and
a decoder for controlling said switches, based on said received directivity data,
wherein said reactance component of said sub antenna is controlled in accordance with an output signal of said decoder.
28. A variable directional antenna comprising:
a main antenna element that is fed from a transmitterreceiver means of an information terminal unit and directly radiates a wave;
a plurality of sub antenna elements for radiating reflecting wave having a predetermined phase shift amount with respect to said wave radiated from said main antenna element;
a strip line for controlling a reactance component of said sub-antenna element;
a plurality of stubs provided in order to change said reactance component of said sub-antenna element;
a plurality of switches for controlling a connection between said stub and said strip line or said stub and the ground so as to be a short stub or an open stub;
a data input for receiving directivity data from said information terminal unit; and
a decoder for controlling said switching means, based on said received directivity data,
wherein said reactance component of said sub antenna is controlled in accordance with an output signal of said decoder.