T. Sehm

A high-gain 58-GHz box-horn array antenna with suppressed grating lobes

A low-profile high-gain antenna array of box horns for the frequency band 57.2-58.2 GHz is presented. The antenna consists of 256 radiating elements divided into two subgroups of 128 elements fed by a rectangular waveguide feed network. The radiating elements are fed in parallel and the waveguides are connected with T-junctions. The matching of the T-junctions is improved with a matching pin and a splitter. Because of the waveguide feed network, the element spacing is larger than one wavelength, which causes grating lobes. The grating lobes and sidelobes in the H-plane have been suppressed by the use of a combination of subarrays, a special characteristic of the box horn, and an array amplitude tapering. The measured sidelobe levels in the H-plane are below -30 dB at angles larger than 8/spl deg/ from boresight. A gain higher than 35.7 dBi and a return loss higher than 14.4 dB have been measured for the antenna over the band 57.2-58.2 GHz.

A large planar 39-GHz antenna array of waveguide-fed horns

A planar antenna in which box horns are used as radiating elements is described. The feed network is built by connecting rectangular waveguides with T-junctions. The matching of the T-junctions is improved by using rounded splitters and matching pins in the junctions. The radiating element has been designed to cancel out the grating lobe. The grating lobe is due to an element spacing larger than one wavelength. The highest sidelobes are at least 31 dB below the main beam in the H-plane and 16 dB in the E-plane. A gain of 37 dBi has been achieved at 39.2 GHz. These results demonstrate the feasibility of this antenna for applications requiring high gain at millimeter wavelengths.

Matching of a rectangular waveguide T junction with unequal power division

Matching of a rectangular waveguide T junction with two matching posts and a splitter is proposed. An unequal power division is realized without a phase difference between the output ports. A return loss more than 30 dB over the frequency range 37.0–39.5 GHz can be achieved according to simulations. Measurements show a return loss larger than 18 dB.

A 38 GHz Horn Antenna Array

A planar antenna array of box horns for the frequency range 37.0-39.5 GHz was designed and tested. Low sidelobes in the H-plane have been realized by combining two box horn arrays shifted sideways. The radiating elements are fed in parallel through a waveguide feed network, where improved T-junctions are used as power dividers. A 64-element antenna array has been built. According to the measurements, a sidelobe level of ¿35 dB in the H-plane at an angle of 36° from the main beam, a gain of 30.4 dBi, and a return loss higher than 16.9 dB have been achieved over the band 37.0-39.5 GHz.

A large planar antenna consisting of an array of waveguide fed horns

A planar array antenna in which box horns are used as radiating elements is proposed. The antenna consists of two parts, one containing the feed network and the other 256 radiating elements. The radiation pattern of the single radiating element is specially designed to cancel out the sidelobes of the array due to the element spacing larger than one wavelength. The feed network is built by connecting rectangular waveguides with T-junctions. The matching of the T-junctions is improved by using rounded splitters and matching pins in the junctions. A planar antenna for the frequency range 37.0-39.5 GHz has been designed. The measured radiation pattern of a prototype antenna is extremely directive in both the E-and H-planes and a gain of 37 dBi at 39.2 GHz has been achieved. The highest sidelobes are at least 31 dB below the main beam in the H-plane and 15 dB in the E-plane.

A 64-element array antenna for 58 GHz

A planar array of box horns is presented for the frequency band 57.2-58.2 GHz. The horns are fed in parallel with a waveguide feed network. Improved T-junctions are used to connect the waveguides. The horns are divided into two subarrays shifted sideways in order to reduce the grating lobe in the H-plane, which is due to the large element spacing. The radiation pattern of the horn is also optimized to reduce H-plane sidelobe levels. The measured H-plane sidelobe level is below -35 dB at angles larger than 18/spl deg/ from boresight with a gain higher than 31 dBi. The measured return loss exceeds 17 dB over the band 57.2-58.2 GHz.

Measurement of a Novel 40 GHz Planar Antenna using Planar Near-field Scanning Techniques and a Hologram CATR

Planar near-field scanning and a hologram type of compact antenna test range (CATR) are used to determine the radiation characteristics of a novel 40 GHz planar antenna. The results are compared with those obtained from a far-field measurement. The near-field scanning method works very well, and as a result, a complete three dimensional radiation pattern is obtained as well as the aperture distribution of the antenna under test (AUT). The same antenna was also measured with a hologram CATR. Despite the fact that the used hologram CATR had a design error making the quiet-zone too small, it was demonstrated that the hologram CATR method is feasible at long millimeter wavelengths.

Low-profile solutions for high-gain antennas and their measurements at millimeter wavelengths

A low-profile antenna design for millimeter wave radio link applications is presented. The antenna has a simple planar array construction, high gain and low enough sidelobes to be ETSI compliant. Measurement with a hologram CATR (compact antenna test range) is also discussed and the results are compared with those from tests in a planar near-field scanning facility and from tests with the traditional far-field method.

A planar high-gain antenna for millimeter wavelengths

The largest single component of a radio relay system is the antenna. Small antennas would promote the possibility of hiding the transmission system in the environment. In this paper a planar array antenna, in which box horns are used as radiating elements, is presented as a possible candidate for planar radio relay antennas at 40 GHz. The antenna consists of two parts, one containing the feed network and the other 256 radiating elements. The measured radiation pattern of a prototype antenna is very directive in both the E- and H-planes and a gain of 37 dBi at 39.2 GHz has been achieved. The highest sidelobes are at least 31 dB below the mainbeam in the H-plane and 16 dB in the E-plane.

Feasibility of different antenna measurement techniques at submillimeter wavelengths

Radiometric instruments with high-gain antennas for space applications in the 200 to 1500 GHz region are under investigation. The measurement of antennas for these kind of applications cannot be made using traditional methods. In this paper, possible methods of measuring large antennas at THz-frequencies, i.e. CATR and near-field scanning techniques are discussed.