A system and method for tuning a transistor-based circuit. The system includes a negative impedance converter circuit having a capacitor, a first transistor, and a second transistor. As a current travels through the capacitor, the first transistor and the second transistor each sample voltage at the capacitor and invert the voltage at an input of the negative impedance converter circuit. The negative impedance converter circuit also has a third transistor in series with the capacitor. The third transistor has a base voltage. Changing the base voltage of the third transistor changes the voltage sampled by the first transistor and the second transistor.

System and method for determining gain characteristics of a circularly-polarized antenna. The method includes receiving a measured first amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a linearly-polarized standard-gain antenna, a measured second amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a circularly-polarized antenna under test, and a measured third amplitude of a forward gain between a circularly-polarized antenna probe of a second type and the circularly-polarized antenna under test. The method also includes determining a left-hand circularly-polarized gain and a right-hand circularly-polarized gain of the circularly-polarized antenna under test based on the measured first amplitude, the measured second amplitude, the measured third amplitude, and a cross-polarization level of the circularly-polarized antenna probes of the first and second types. The determination may be performed using one or more processors.

System and method for determining gain characteristics of a circularly-polarized antenna. The method includes receiving a measured first amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a linearly-polarized standard-gain antenna, a measured second amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a circularly-polarized antenna under test, and a measured third amplitude of a forward gain between a circularly-polarized antenna probe of a second type and the circularly-polarized antenna under test. The method also includes determining a left-hand circularly-polarized gain and a right-hand circularly-polarized gain of the circularly-polarized antenna under test based on the measured first amplitude, the measured second amplitude, the measured third amplitude, and a cross-polarization level of the circularly-polarized antenna probes of the first and second types. The determination may be performed using one or more processors.

A half-rhombic antenna includes an addressable switch at the apex. The addressable switch is opened or closed base on the operating frequency of the antenna. The addressable switch is open when operating at odd multiples of the lowest frequency and closed when operating at even multiples of the lowest frequency. The feedpoint includes a tuning element to adjust impedance within a range defined by the operating range of the switched antenna.

A half-rhombic antenna includes an addressable switch at the apex. The addressable switch is opened or closed base on the operating frequency of the antenna. The addressable switch is open when operating at odd multiples of the lowest frequency and closed when operating at even multiples of the lowest frequency. The feedpoint includes a tuning element to adjust impedance within a range defined by the operating range of the switched antenna.

System and method for determining gain characteristics of a circularly-polarized antenna. The method includes receiving a measured first amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a linearly-polarized standard-gain antenna, a measured second amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a circularly-polarized antenna under test, and a measured third amplitude of a forward gain between a circularly-polarized antenna probe of a second type and the circularly-polarized antenna under test. The method also includes determining a left-hand circularly-polarized gain and a right-hand circularly-polarized gain of the circularly-polarized antenna under test based on the measured first amplitude, the measured second amplitude, the measured third amplitude, and a cross-polarization level of the circularly-polarized antenna probes of the first and second types. The determination may be performed using one or more processors.

System and method for determining gain characteristics of a circularly-polarized antenna. The method includes receiving a measured first amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a linearly-polarized standard-gain antenna, a measured second amplitude of a forward gain between a circularly-polarized antenna probe of a first type and a circularly-polarized antenna under test, and a measured third amplitude of a forward gain between a circularly-polarized antenna probe of a second type and the circularly-polarized antenna under test. The method also includes determining a left-hand circularly-polarized gain and a right-hand circularly-polarized gain of the circularly-polarized antenna under test based on the measured first amplitude, the measured second amplitude, the measured third amplitude, and a cross-polarization level of the circularly-polarized antenna probes of the first and second types. The determination may be performed using one or more processors.