Showing papers on "Active antenna published in 2017"

Prediction of Nonlinear Distortion in Wideband Active Antenna Arrays

Abstract: In this paper, we propose a technique for comprehensive analysis of nonlinear and dynamic characteristics of multi-antenna transmitters (TXs). The analysis technique is enabled by the development of a Volterra series-based dual-input model for power amplifiers (PAs), which is capable of considering the joint effects of PA nonlinearity, antenna crosstalk, and mismatch for wideband modulated signals. By combining multiple instances of the PA model with linear dynamic antenna simulations, we develop the analysis technique. The proposed method allows the prediction of the output signal of every antenna in an arbitrarily sized TX array, as well as the total far-field radiated wave of the TX for any input signal with low computational effort. A 2.12-GHz four-element TX demonstrator based on GaAs PAs is implemented to verify simulation results with measurements. The proposed technique is a powerful tool to study hardware characteristics as, for example, the effects of antenna design and element spacing. It can be used in cases where experiments are not feasible, and thus aid the development of next generation wireless systems.

Analysis of nonlinear distortion in phased array transmitters

Abstract: This paper investigates nonlinear distortion effects in active antenna phased array transmitters. Using a nonlinear modeling technique, the joint interactions between power amplifiers and antennas are investigated in detail. Numerical simulations based on a 28 GHz GaN MMIC PA and a 64-element antenna array are used to exemplify the use of the proposed technique in a typical 5G application. The results show that the antenna mutual coupling will cause the individual PA compression characteristics and hence the far field distortion to depend significantly on beam steer angle.

Synthesis of Pattern Reconfigurable Sparse Arrays With Multiple Measurement Vectors FOCUSS Method

Abstract: A new technique based on the multiple measurement vectors FOCal Underdetermined System Solver (M-FOCUSS) for synthesis of pattern reconfigurable sparse arrays is presented. The method, based on the MMVs sparse recovery theory, is used for finding the common element positions and individual element excitations for multiple patterns in the guidance of collaborative synthesis strategy. A reasonable tradeoff between the number of active antenna elements and pattern characteristics can be achieved. Numerical examples show the high efficiency and robustness of the proposed method. Furthermore, the M-FOCUSS method is combined with the active element pattern technique so that the mutual coupling between real antennas can be taken into account in the synthesis process. The M-FOCUSS-Active algorithm is used to design an E-plane coupled microstrip antenna array. Measured results validate the effectiveness of this approach.

An Active Microwave Sensor for Near Field Imaging

Abstract: Near-field imaging using microwaves in medical applications is of great current interest for its capability and accuracy in identifying features of interest, in comparison with other known screening tools. This paper documents microwave imaging experiments on breast cancer detection, using active antenna tuning to obtain matching over a wide bandwidth. A simple phantom consisting of a plastic container with a low dielectric material emulating fatty tissue and a high dielectric constant object emulating a tumor is scanned between 4 and 8 GHz with a ultra-wideband microstrip antenna. Measurements indicate that this prototype microwave sensor is a good candidate for such imaging applications.

C-Band Active-Antenna Design for Effective Integration With a GaN Amplifier

Abstract: This paper aims to effectively integrate a GaN amplifier into a high-efficiency active-antenna design. In this paper, the antenna is designed for a GaN high-electron-mobility-transistor (HEMT) impedances calculated by a load–pull simulation with a GaN nonlinear model, which contributes to a lossless design and prevents power-added-efficiency (PAE) reduction by active-antenna integration. The antenna impedance is selected to reduce the impedance-transform ratio with the GaN HEMT. In addition, the active antenna includes a second-harmonic-tuning circuit for high efficiency. The active antenna comprises antenna- and amplifier-circuit layers piled onto a Peltier unit, which has a high affinity with this cooling systems. The antenna and amplifier circuits are designed on low- and high-dielectric substrates, respectively, enabling the amplifier to be downsized and the antenna gain to be increased. Each layer is connected by a through-hole. First, the single-stage amplifier is fabricated with a maximum output power of 37.95 dBm and a maximum PAE of 62.94%. Next, the GaN active antenna is fabricated with a maximum effective isotropically radiated power of 44.61 dBm and a maximum antenna gain of 23.99 dBi. The assumed amplifier large-signal characteristics of the active antenna agree with those of the single-stage amplifier. Therefore, the amplifier and the antenna are integrated without loss.

A Low-Power 28-nm CMOS FD-SOI Reflection Amplifier for an Active F-Band Reflectarray

Abstract: A new topology of a low-power F-band reflection amplifier for active reflectarrays is proposed and demonstrated using a CMOS fully depleted silicon-on-insulator 28-nm process. The design enables frequency response and center frequency tuning, as well as phase control of the reflected signal. The chip consumes a core area of only $90\times 80~\mu\text{m}^{2}$ and is incorporated into a $2\times 2$ printed reflectarray antenna, implementing the first co-polarized active reflectarray. Such implementation enables, for the first time, active reflectarrays with dual polarization ability, which can be used for full-duplex links, as well as polarization diversity applications. Design considerations for a stable reflection amplifier, as well as measurement results of the reflection amplifier and reflectarray, are presented in this paper. Variable stable gain of 5–25 dB at the frequency range of 106–127 GHz was achieved, with noise figure of 10.5–11.7 dB. The total power consumption was 6–20 mW, depending on the chosen frequency response. An active antenna gain of 28 dBi was measured for the $2\times 2$ reflectarray.

A 28 GHz 480 elements digital AAS using GaN HEMT amplifiers with 68 dBm EIRP for 5G long-range base station applications

Abstract: This paper reports the design, development and performance of a 28 GHz 480 elements digital Active Antenna System (AAS) prototype for 5G long-range applications. AAS accommodates 32 channels of 0.15 um GaN HEMT power amplifier chains. The antenna array prototype consists of full digitally controlled 32 streams of 15 elements sub-arrays. They can deliver a total conductive power of 41 dBm and Average Effective Isotropically Radiated Power (EIRP) of 68 dBm for the macro-cell coverage at 28 GHz. The prototype also features newly proposed high density heat spreading structure dissipating around 450 W in an 11 liter compact enclosure. The paper proposes and demonstrates one of direction of the high power GaN HEMT application to the millimeter-wave 5G long-range base stations.

Design and Measurements of 100 GHz Reflectarray and Transmitarray Active Antenna Cells

Abstract: A reflectarray antenna, based on a single polarization element, by using a one port reflection amplifier is presented. A $2 \times 2$ subarray of the reflectarray was implemented by patch antennas, integrated with reflection amplifiers fabricated in a CMOS technology. In addition, a 100 GHz $2 \times 2$ active subarray for a transmitarray antenna was also designed and fabricated, using a two-port high-gain phase rotator. Design principles and the integration process are presented. Both antennas can be used for either phased array or for spatial modulation applications, as presented in this paper. Finally, the implementation of multilevel ASK spatial modulators employing the transmitarray is demonstrated.

Reflection Reduction Through Modal Filtering for Integrated Antenna Measurements Above 100 GHz

Abstract: Feeding integrated antennas during a measurement requires special feeding structures Due to the small antenna dimensions, these feeding structures are often much bigger than the antenna under test (AUT) itself and with chip sizes of around 1 mm2, the achievable separation between antenna and feed is limited Wafer probes have to be used to feed the AUT during passive antenna measurements and present a large reflective surface in close proximity to the AUT Reflections from the wafer probe cause interference on the measurement surface and distort the results The same is true for active antenna measurements, where bondwires and the package can have a significant effect on the radiated fields The fragility and size of the components do not allow to reduce reflections with absorbers, which is why modal filtering was used in this paper to mitigate undesired reflections and improve the measurement result through postprocessing Two issues that limit the performance of the algorithm are discussed, namely, phase center inaccuracies of the AUT and a limited measurement surface It is shown that modal filtering is applicable to integrated antenna measurements at frequencies over 100 GHz and that a significant improvement in the measured radiation pattern can be achieved Furthermore, it is shown that the postprocessed results make it possible to measure the directivity of integrated antennas, despite strong probe reflections

Performance Analysis of Compact FD-MIMO Antenna Arrays in a Correlated Environment

Abstract: Full dimension multiple-input-multiple-output (FD-MIMO) is one of the key technologies proposed in the third Generation Partnership Project (3GPP) for the fifth generation communication systems. The reason can be attributed to its ability to yield significant performance gains through the deployment of active antenna elements at the base station in the vertical as well as the conventional horizontal directions, enabling several elevation beamforming strategies. The resulting improvement in spectral efficiency largely depends on the orthogonality of the sub-channels constituting the FD-MIMO system. Accommodating a large number of antenna elements with sufficient spacing poses several constraints for practical implementation, making it imperative to consider compact antenna arrangements that minimize the overall channel correlation. Two such configurations considered in this paper are the uniform linear array (ULA) and the uniform circular array (UCA) of antenna ports, where each port is mapped to a group of physical antenna elements arranged in the vertical direction. The generalized analytical expression for the spatial correlation function (SCF) for the UCA is derived, exploiting results on spherical harmonics and Legendre polynomials. The mutual coupling between antenna dipoles is accounted for and the resulting SCF is also presented. The second part of this paper compares the spatial correlation and mutual information (MI) performance of the ULA and UCA configurations in the 3GPP 3-D urban-macro and urban-micro cell scenarios, utilizing results from random matrix theory on the deterministic equivalent of the MI for the Kronecker channel model. Simulation results study the performance patterns of the two arrays as a function of several channel and array parameters and identify applications and environments suitable for the deployment of each array.

Space-Time Index Modulation

Abstract: In this paper, we present a new multi-antenna modulation scheme, termed as space-time index modulation (STIM). In STIM, information bits are conveyed through antenna indexing in the spatial domain, slot indexing in the time domain, and M-ary modulation symbols. A time slot in a given frame can be used or unused, and the choice of the slots used for transmission conveys slot index bits. In addition, antenna index bits are conveyed in every used time slot by activating one among the available antennas. M-ary symbols are sent on the active antenna in a used time slot. We study STIM in a cyclic-prefixed single-carrier (CPSC) system in frequency-selective fading channels. It is shown that, for the same spectral efficiency and single transmit RF chain, STIM can achieve better performance compared to conventional orthogonal frequency division multiplexing (OFDM). Low-complexity iterative algorithms for the detection of large-dimensional STIM signals are also presented.

Sensitivity of an Active Antenna Array Element for the Low-Frequency Radio Telescope GURT

Abstract: The recently developed new generation, low-frequency Giant Ukrainian Radio Telescope (GURT) is built nearby the well-known Ukrainian T-shaped Radio Telescope. The new facility employs a phased antenna array composed of many subarrays of $5 \times 5$ active antenna elements. In this paper, the parameters of the active antenna used as array element are studied, with special attention paid to sensitivity. The electrical and noise parameters are calculated using computer simulation and wave techniques for noise modeling of two-port networks. The results of numerical calculations of the sensitivity are given in terms of the sky noise dominance (SND) and system equivalent flux density of the GURT element within 10–80 MHz. The calculated results are compared with in situ measurements.

Reconfigurable frequency selective surface for beam-switching applications

Abstract: A novel design for a beam-switching antenna based on a new reconfigurable frequency selective surface (FSS) is presented at 2.1 GHz operating frequency. The antenna system consists of an omnidirectional antenna and a cylindrical FSS for controlling its radiation pattern characteristics. The discontinuous split-ring resonator (SRR) cross-shape FSS is composed of 12 FSS unit cells with 4 active elements in each one. To reconfigure the radiation pattern of the antenna, a PIN-diode is specifically placed in the discontinuity of the FSS hybrid element for its switching functions. The antenna radiation sector is determined by the off-state diodes. This design is used to realise a beam-switching active antenna covering all azimuth angles. The measurement results are in line with the simulation and confirm the proposed configuration of the antenna. The measurement of the proposed design at the operating frequency resulted in a gain of 8.1 dBi. This antenna can be used in the base station of the wireless communication systems.

A Novel Pattern-Reconfigurable Oscillating Active Integrated Antenna

Abstract: A new topology to reconfigure the radiation pattern in feedback-type oscillating active integrated antenna (AIA) is proposed and demonstrated in this letter. The proposed active antenna consists of an array of two patch elements as a passive radiator integrated with an active device to form a feedback-type oscillating active antenna. Three states (main beam at θ = 0°, +30°, and −30°) of the broadside radiation pattern are obtained. Oscillations are stable in all the states. The proposed structure is fabricated and tested; measured results verify the antenna operation in all three states of the radiation pattern. The proposed structure is suitable for power-combining application at millimeter-wave frequencies.

Spatial-Modulation-Based Wireless-Powered Communication for Achievable Rate Enhancement

Abstract: In this letter, we propose to utilize spatial modulation (SM) at the wireless device (WD) in a wireless-powered communication (WPC) system for information transmission (IT) by mapping information to the active antenna indices, so that the remaining antennas can be dedicated to energy harvesting (EH) simultaneously. Consequently, the proposed scheme enjoys the advantages of improved system achievable rate (AR), simultaneous EH and IT, and self-energy recycling (SE-R) while requiring no backhaul links between the WD and the information receiver. Numerical results verify the AR enhancement of the proposed scheme with a Gaussian input over the existing time switching-based WPC protocol, the antenna selection-based WPC protocol, and SE-R without SM.

Head mounted display with multiple antennas

Abstract: A head-mounted display (HMD) is provided, including the following: a transceiver; a plurality of antenna arrays; a selector configured to determine which of the antenna arrays is active for wireless communication of data by the transceiver; a display configured to render video data received by the transceiver through the active antenna array.

Reflective antenna array and beam scanning method

Abstract: The invention discloses a reflective antenna array and a beam scanning method. The reflective antenna array comprises a programmable substrate and a metamaterial surface, wherein the metamaterial surface comprises a plurality of active antenna units, and the active antenna unit comprises a metamaterial unit and an active diode connected between the metamaterial units. When the states of the active diodes are arranged differently, 0 and 1 states on the surface of the metamaterial are distributed differently, and further, plane waves are reflected to a needed radiation beam. Corresponding 0 and 1 coding arrangement can be quickly designed, corresponding active diode is quickly controlled through the programmable substrate, and the beam scanning angle and the radiation beam are controlled. In comparison with the traditional structure, a radiation beam with a needed direction angle can be realized without mechanically rotating the antenna structure, the overall size is reduced, and the flexibility is enhanced.

Generalized spatial modulation with transmit antenna grouping for massive MIMO

Abstract: In this paper, an effective low complexity generalized spatial modulation (GenSM) scheme with transmit antenna grouping is proposed for massive multi-input multi-output (MIMO) system to deal with the channel correlation among transmit antennas. In the proposed scheme, all transmit antennas are divided into several equal-sized groups, and spatial modulation (SM) is carried out to select one active antenna in each group independently. Two different grouping methods, i.e., block grouping and interleaved grouping, are introduced to optimize the error performance in low and high signal-to-noise ratio (SNR) region, respectively. In consideration of the large amount of transmit antennas in a massive MIMO system, both linear and 2-dimensional transmit antenna arrays are considered in our design. To evaluate the performance, a closed-form expression of the average bit error probability (ABEP) upper bound is derived for all proposed grouping methods and Monte-Carlo simulations are conducted to verify the analysis and reveal the performance gain of the proposed scheme in terms of bit error rate (BER) in comparison with conventional GenSM.

Novel Reception and Transmission Calibration Technique for Active Antenna Array Based on Phase Center Estimation

Abstract: This paper presents an on-site calibration technique and significant results obtained from the compensation of errors and mutual coupling. The proposed algorithm deals with the problem of calibration of active antenna arrays at reception and transmission, proposing an on-site calibration technique. The proposed on-site calibration technique starts with the application of an off-line calibration algorithm of which two different techniques are proposed. These techniques are based on the direct estimation of the phase center from the active element pattern measured, and the phase center estimation based on the active element pattern suggested. The expansion of equations of the proposed off-line calibration algorithms is also presented. These algorithms deal with the compensation of mutual coupling effect and together with gain, phase, and location errors.

Method and apparatus for reference signal transmitting and receiving in active antenna systems

Abstract: Embodiments of the present disclosure provide reference signal transmitting and receiving methods and devices in an active antenna system. Port virtualization to a transmit antennas may be implemented for multiple cell-specific reference signal (CRS) antenna ports and applying different vertical beamforming vectors to implement port virtualization for the different CRS antenna ports. The User Equipment (UE) reports the maximum RSRP/RSRQ value measured based on multiple CRS ports, or the UE simultaneously reports multiple RSRP/RSRQ values and the information of the multiple CRS antenna ports. Therefore, the coverage problem of the CRS signal and Physical Broadcast Channel (PBCH)/Physical Downlink Control Channel (PDCCH)/Physical Downlink Shared Channel (PDSCH) demodulated based on CRS and the problem of measurement for Radio Resource Management (RRM) in the active antenna system may be avoided. Specifically, the following problems may be solved. 1) Coverage differences between CRS and PBCH/PDCCH/PDSCH demodulated based on CRS transmission and Enhanced PDCCH (E-PDCCH)/PDSCH signal transmission, which is measured based on the CSI-RS or demodulated based on the DMRS may be reduced or avoided. 2) The cell association problem due to the different vertical beamforming technologies adopted by the CSI-RS or DMRS and by the CRS may be avoided. 3) Deep spatial fading state may be avoided for CRS reception and PBCH/PDCCH/PDSCH demodulated based on the CRS.

Three ports microstrip patch antenna with dual linear and linear co-polarisation characteristics

Abstract: In this Letter, three ports proximity coupled microstrip patch antenna with linear co-polarisation and linear dual polarisation characteristics has been presented for in-band full duplex and active antenna applications. Depending upon the excitation ports, antenna can perform transmit and receive operation either with dual linear polarisation or linear co-polarisation at same carrier frequency with dc isolated ports in both cases. It provides >10 dB interport isolation with linear co-polarisation when compared with around 2.5 dB port-to-port isolation of simple linear co-polarised antenna with two anti-parallel feeds. With dual polarisation, interport isolation is >43 dB at centre frequency when compared with 36 dB port isolation provided by dual polarised antenna with two orthogonal feeds. Proposed antenna has been implemented on FR4 substrate to compare its simulated and measured input matching and port-to-port isolation performances.

A cost-effective wearable vital-sign sensor with self-oscillating active antenna based on envelope detection technique

Abstract: A wearable vital-sign sensor with the self-oscillating active antenna is proposed in this paper. The active antenna is employed to radiate the radio-frequency signal and receive the injection signal reflected from the moving human chest. Since the envelope detection technique is adopted to demodulate the vital signs from the modulated output of the active antenna, the circuit complexity, cost, and circuit size can be significantly reduced. The developed sensor is experimentally validated to detect the respiration and heartbeat rate of a human adult. The measured heartbeat rate agrees that obtained by the finger pulse oximeter very well.

Antenna grouping assisted spatial modulation for massive MIMO systems

Abstract: In this paper, an antenna grouping assisted spatial modulation scheme is proposed for massive MIMO systems. Massive multiple-input-multiple-output (MIMO) systems are capable of offering abundant spatial capacity by deploying hundreds of antennas at the base station (BS). Spatial modulation (SM) is one of the key technologies in exploiting spatial capacity, which maps the information bits to the active antenna patterns. However, the classical SM having only one radio frequency (RF) chain to be active significantly reduces the spatial multiplexing gain offered by massive antennas. Generalised spatial modulation (GSM) is an extension of SM, which allows several antennas to be active. With multiple active antennas, the throughout improves while the bit error ratio (BER) performance becomes poor. Thus, we propose an antenna grouping assisted spatial modulation, which is called as grouping SM (GrSM). Explicitly, the transmitting antennas are partitioned into multiple groups based on their channel characteristics and each group activates a single antenna for delivering signals. Furthermore, the upper bound of the BER of the proposed GrSM is also theoretically analyzed. Simulation results are presented to verify the effectiveness of the proposed GrSM in terms of achievable BER performance with same bit rate in comparison with SM and GSM.

Active antenna calibration

Abstract: Aspects of this disclosure relate to active antenna calibration In some embodiments, a local oscillator signal can be injected into the receive path for misalignment measurement and calibration of the receive path, a transmit signal from a transmit path can be coupled to a receive path, and the transmit path can be calibrated relative to the receive path

Robust monopulse beam synthesis with sparse elements in linear and planar arrays with element failure detection

Abstract: In this study, the authors present monopulse beam synthesis methods with sparse elements robust to the antenna module failure. The monopulse beam radar generates two beams (sum/difference beams) simultaneously and it requires a large number of antenna elements in antenna arrays. However, it is desirable to reduce the number of active antenna elements. Furthermore, in many practical applications, some of antenna elements may experience the module failure. Accordingly, to design beams robust to the module failure and reduce the number of active antenna elements simultaneously, the authors propose a modified reweighted L1 minimisation methods in which the Bayesian-inference-based failure probability is exploited. The authors also discuss how the proposed sparse beam synthesis method can be carried out successfully in conjunction with the array failure diagnosis based on the Bayesian compressive sensing.

Sidelobe reduction with a GaN active array antenna

Abstract: This work proposes a tunable sidelobe reduction method based on a GaN active-antenna technique, in which the output radio frequency power is controlled by the DC drain voltage of the amplifiers. In this study, a 1 × 4 array of active antenna with GaN amplifiers is designed and fabricated. GaN amplifiers capable of up to 10 W-class power output are fabricated and arranged for a four-way active-array antenna. The fabricated single-stage GaN amplifier offers a maximum power-added efficiency of 59.6% and a maximum output power of 39.3 dBm. The maximum output power is decreased to 36.5 dBm upon decreasing the operating drain voltage from 55 to 35 V. In this study, a 4.5 dB sidelobe reduction is demonstrated in a 1 × 4 active antenna based on this output power difference for each amplifier.

Spatial Multiplexing of OFDM Signals With QPSK Modulation Over ESPAR

Abstract: An electronically steerable parasitic array radiator (ESPAR) transmitter, employing one active and one parasitic antenna element, which can simultaneously transmit two orthogonal frequency division multiplexing (OFDM) signals with quadrature phase shift keying (QPSK) modulation via spatial multiplexing, is developed. In particular, a minimum mean square error (MMSE) scheme for quantizing the parasitic load impedance is developed to reduce the number of distinct load impedance values that should be realized for spatial multiplexing over ESPAR. To this end, the probability density function of the parasitic load impedance is derived, and the realizable region of the load impedance is analyzed. It is observed that the resistance of the active antenna element should be large enough to transmit OFDM signals. The characteristics of two existing ESPAR antennas with different mutual coupling matrices are examined, and it is observed that the one with the larger active antenna resistance is suitable for OFDM transmission. The bit error rate (BER) and the receive error vector magnitude performances of the proposed ESPAR systems with 6/8-bit quantizers and zero-forcing (ZF) receiver are compared with those of the corresponding ideal multiple-input multiple-output (MIMO) system through computer simulation. The results demonstrate that the performances of the proposed ESPAR with the 8-bit quantizer and the ideal MIMO systems can be almost identical, whereas the proposed ESPAR with the 6-bit quantizer exhibits some performance loss.

A sequential power amplifier at 3.5 GHz for 5G applications

Abstract: In this paper, a broadband Sequential Power Amplifier (SPA) is designed and realized for the use in an active MIMO antenna around 3.5 GHz. For that purpose, specifications for the individual components are derived to yield optimum performance of the complete SPA when amplifying a mobile communication signal. In order to meet the size requirements of an active antenna, amplifier modules that include all necessary transformation and stabilization networks inside the package are developed. The SPA achieves a bandwidth of more than 1 GHz (RBW of 28%) and shows a peak drain efficiency of 47% in 8 dB backoff at 3.5 GHz. To transmit a complex signal such as QAM using the SPA, its two inputs have to be driven according to the system's characteristic curve. For the first time, modified constellation diagrams for each input have been derived to transmit a 16-QAM-modulated test signal with 10 MBaud at 3.2 GHz. For the amplification of this signal, the system shows an increase in drain efficiency of 10 %-points compared to a conventional class-B PA.

Reconfigurable Antenna for Jamming Mitigation of Legacy GPS Receivers

Abstract: We propose a simple solution for jamming mitigation of L1 band GPS by electronically switching antenna beam for wide and narrow beamwidths. Assuming the jamming signal is directed from low elevation angles, antenna reception can be made significantly lower at these angles by electronically reconfiguring the antenna beamwidth. Four-element antenna array and one of the elements of the array are designated as antijam (array) mode and normal mode of the antenna. The antenna is placed on a degenerate-ground with symmetric slots in the ground. Front-end configuration for this antenna is also discussed. Simulations and measurements are performed to validate the proposed design. The antenna achieves more than 15 dB rejection in measurements and more than 20 dB cross-polarization improvement compared to standalone (normal mode) antenna. The system can easily be replaced with existing active antenna to improve antijam capability of the receiver.

Two-Port Reconfigurable Passive Radiator with Switchable Pattern for Active Antenna Application

Abstract: A two-port reconfigurable passive radiator with pattern switching capability and its application in designing of oscillating feedback loop active integrated antenna (AIA) is reported in this paper. Passive radiator consists of two element array of microstrip patch, fed by electromagnetically coupled T-shaped microstrip line. Proposed structure contains feed port (port 1) and coupled port (port 2). Proposed antenna is capable to switch the beam among sum and difference pattern by turning PIN diodes ON or OFF. As an application, oscillating feedback loop active integrated antenna (AIA) is designed by connecting this two-port passive radiator in the feedback path. Two-port passive radiator is fabricated and tested. Measured results are reported and compared with the simulated results. Proposed AIA design is simple and easy to fabricate can be used as a fixed frequency generator and key element for power combining arrays.